PART A&B: TECHNICAL SPECIFICATION FOR OUTDOOR 11 KV … · SF6 insulated VCB of suitable rating - e) 6-way ,11KV Gas (SF6) Insulated RMU with 3Nos 630A Load break switches and 3Nos

TENDER NO:MGVCL/RAPDRP/SCADA/148

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PART A&B: TECHNICAL SPECIFICATION FOR OUTDOOR 11 KV RING MAIN UNIT

SWITCHGEAR

1.1 GENERAL:

1.1.1 All equipment and material shall be designed manufactured and tested in

accordance with the latest applicable IEC standard.

1.1.2 Equipment and material conforming to any other standard, which ensures equal or

better quality, may be accepted. In such case copies of English version of the

standard adopted shall be submitted.

1.1.3 The electrical installation shall meet the requirement of Indian Electricity Rules-1956

as amended up to date; relevant IS code of practice and Indian Electricity Act-1910.

In addition other rules and regulations applicable to the work shall be followed. In case any discrepancy ,the

most stringent and restrictive one shall be binding.

1.1.4 The high-tension switchgear offered shall in general comply with the latest issues

including amendments of the following standards but not restricted to them.

1.2 SCOPE:

Design, Engineering, Manufacture, assembly, Stage testing, inspection and testing before supply and delivery at site,

Erection, Installation, testing & Commissioning of Ring Main units outdoor type SF6 filled , with various combinations

of load break isolators & breakers. The scope includes Supply, Erection, testing and commissioning of outdoor type

RMU with necessary take off terminal units for future automations contains load break isolators, breaker and

associated accessories, equipments. (including civil works and earthing- Erection of earthing by using GI strip

(minimum 35 mm strip) with earthing plate including cost of coal/salt to RMU). The Installation of 11KV Outdoor SF6

Insulated RMU covering erection,testing and commissioning with associated equipment including civil work of RMU,

drawing and Bom(Bill of Material) of civil work submit by bidder along with technical details.

The RMUs should be provided with necessary take off terminal units for future automations and all these units should

be shielded in a outdoor metal-body for making them suitable for outdoor use. The insulation/dielectric media inside

the stainless steel welded tank should be SF6 gas. The RMUS should be Modular ,extensible type on both sides with

provision of attaching/connecting with SNAP FIT arrangement W/o External Busbars additional load break switches

and circuit breakers in future whenever required. Alternatively Extension shall be possible by adding trunking

chambers and required accessories or by plug-in bushing type arrangement.

The Package scope of work shall include survey, design, manufacture, FAT and delivery,

installation and commissioning of new SCADA enabling equipments of new “SCADA-Ready”

The RMU should have compatibility with OPEN PROTOCOL SCADA system.

Ring Main Units capable of being monitored and controlled by the SCADA/DMS. The RMU should have the castle lock

for avoiding dual supply and safety purpose.


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Where relevant, the RMU scope of work shall be coordinated with the work to be carried out under the project’s other

construction packages & associated materials to the designated destinations as per this tender specification and Bill of

quantities. Includes supply of relevant 11KV cable termination kits per this tender Specification.

Each RMU shall include its own power supply unit (including auxiliary power transformer, batteries, and battery

charger), which shall provide a stable power source for the RMU. The RMUs will be connected to the FRTU which will

be procured, supplied and installed as a part of Part A of R-APDRP. The RMU will also supply 230VAC 500VA for FRTU.

Refer Annexure-1.

FRTU, MODEM, Power and I/O cable interface between FRTU and Control panel of RMU/sectionaliser are excluded in

the scope of supply and these items will be provided by DISCOM/SIA.

Each new RMU shall be equipped with main-line load break switches and a fault passage indicator (FPI). Furthermore,

to protect each of its lateral / transformer feeders, it shall be equipped with a corresponding set of circuit breakers

and self-powered numerical relays. The RMU shall include potential-free contacts and control contacts so as to

connect to SCADA/DMS via FRTUs, so as to:

� Monitor and control the open/closed status of the RMU circuit breakers and load break switches.

� Monitor the local/remote position of RMU motorised (in case if failure of motor) manually-operated

switches that can be used to enable and disable remote monitoring.

� Monitor the health of the power supply, which will include battery failure and low voltage indications.

� Monitor the open/closed status of RMU earthing switches.

� Monitor the open/closed status of RMU enclosure doors in case of Hinge doors.

� Monitor for low SF6 gas pressure indication.

� Monitor for circuit breaker relay operations.

� Monitor for indication of main-circuit fault detected by the RMU’s FPI.

1.2.1 Configurations Required:-

11KV RMU

a) 2-Way , 11KV Gas (SF6) Insulated RMU with One 630A load break switches

and One SF6 Insulated VCB of suitable rating -

b) 3-way , 11KV ,Gas (SF6) Insulated RMU with 2Nos 630A load break switch

and 1No. SF6 insulated VCB of suitable rating -

c) 4-way ,11KV Gas (SF6) Insulated RMU with 2Nos 630A Load break switches

and 2Nos , SF6 Insulated VCB of suitable rating –


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d) 5-way , 11KV ,Gas (SF6) Insulated RMU with 2Nos 630A load break switch


e) 6-way ,11KV Gas (SF6) Insulated RMU with 3Nos 630A Load break switches


PLS NOTE: THE NOMINAL CURRENT RATING OF VCB SHALL BE ACCORDING TO LOAD OF THE FEEDER AND

ACCORDINGLY SUITABLE RELAY SHALL BE PROVIDED AND ANY CHANGE IN COMBINATION/CONFIGURATION SHALL

BE EXECUTED WITH THE APPROVAL OF CHIEF ENGINEER OF RESPECTIVE DISCOM.

1.1 This Specification provides for design, manufacture, inspection and testing before dispatch, packing and

delivery F.O.R.(Destination) of SF6 insulated RMUs with necessary take off terminal units for future automations,

compatible with SCADA system other accessories and auxiliaries equipment and mandatory spares, described herein

and required for their satisfactory operation.

1.2. The objective of the RMUs is for extremely small construction width, compact, maintenance free, independent

of climate, easy installation, operational reliability, Safe and easy to operate, minimum construction cost, minimum

site work and minimum space requirement.

1.3. The RMUs shall conform in all respects to high standards Of Engineering design, workmanship and latest

revisions of relevant standards at the time of offer.

RMU to be installed on Plinth Erection of plinth with cost of cement etc as per below requirement Plinth size

minimum 5’x4’x2’ or as per required Cement ratio 1: 2 : 4 ;Weight of RMU 510 kg to 1000 kg.

1.4. The type of the 11 KV circuit breaker shall be VCB and insulating medium for load break isolators, Earth switch,

11 KV Buses and other associated equipments should be SF6 gas.

� Necessary current sensors / transformers for protection and metering (wherever required).

� All necessary dry (potential-free) contacts for indications relevant to RMU monitoring status and control.

� A PT Panel including auxiliary power transformer for measurement of system voltage and for charging the

batteries.

� Battery and battery charger, to provide stable as per motor rating, 24 VDC, power for the RMU’s motors.

� Capacitor voltage dividers serving live-line cable indicators.

1.3 GENERAL:

The Ring Main Unit shall be installed at 11 KV junction points to have continuous supply by isolating faulty sections.

The RMU shall be extensible on both sides and consists of the following combinations of load break switches and

Circuit breakers for a nominal voltage of 12 KV using SF6 gas as insulating and Vacuum as arc quenching medium.


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The RMU and combination shall be tropicalised and outdoor metal enclosed type. The RMU metal parts shall be of

high thickness, high tensile steel which must be grit/short blasted, thermally sprayed with Zinc alloy, phosphate or

should follow the 7 tank pre-treatment process and be subsequently painted with polyurethane based powder paint.

The overall paint layer thickness shall be not less than 80 microns.

Relevant IE rules for clearances, safety and operation inside the enclosure shall be applicable. The enclosure shall be IP

54 and type tested for weather proof at EREDA/CPRI.

All live parts except for the cable connections in the cable compartments shall be insulated with SF6 gas. The SF6 gas

tank shall be made of robotic or TIG or MIG welded stainless steel, to have the best weld quality. The gas cubicle shall

be metal enclosed with stainless Steel of thickness as per IEC tested/ designed so as to provide safety and to avoid

leakage of gas and should be provided with a pressure relief arrangement away from operator.

Both the load break switches and the tee off circuit breaker must be motorized.

The cable box of isolators and circuit breakers both should be of front access type as per site requirement.

Any accidental over pressure inside the sealed chamber shall be limited by the opening of a pressure-limiting device in

the top or rear-bottom part of the tank or enclosure. Gas will be release to the rear of the switchboard away from the

operator and should be directed towards the bottom, into the trench to ensure safety of the operating personnel and

the pedestrians / civilians. All the manual operations should be carried out on the front of the switchboard.

GENERAL TECHNICAL REQUIREMENTS

1 Fixed type SF-6 gas insulated / Vacuum circuit breakers. It should be maintenance free, having stainless steel

robotically/ TIG / MIG welded enclosure for IN DOOR / OUTDOOR RMU. However, offer with high quality of the

welding which has necessary extensive leakage test with leak rate of 0.1% per annum can be accepted. The RMUs to

be used are only outdoor type.

2 Low gas pressure devices- 1.2 Bar pressure. RMU should have full rating with 0.0 Bar gas pressure.

3 Live cable indicators- High operator safety.

4 Fully Rated integral ear thing switch on each device.

5 Self powered Microprocessor Based relay- Does not require any external source of power.

6 Units fully SCADA Compatible. Retrofitting at site possible at a later date. Line switches (Load break switches) as well

as T- OFF circuit Breaker can be operated by remote. ( Manual operations should be possible in case of motor failure.)

7 For indoor Cable boxes should be front access and interlocked with earth switch. No rear /side access required. For

outdoor RMUs cable boxes shall be on front.

8 Cable testing possible without disconnection of cables.

9 Compact in dimension.

10 Circuit Breaker with self powered O/C & E/F RELAY.


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11 Low pressure, sealed for life equipment, can operate at “0” bar pressure.

12 Cable ear thing switch on all switching device-standard, for operator safety.

13 Enclosure with IP 54 standard protection for OUTDOOR RMUs and IP2X for INDOOR RMUs

14 All live parts should be inside a stainless steel enclosure for out door type RMU & minimum 2 mm thickness of

stainless steel robotically/TIG/MIG welded enclosure for Outdoor / indoor RMU.

TECHNICAL AND GUARANTEED PARTICULARS:

The bidders shall furnish all guaranteed technical particulars as called for in Schedule “A” of this specification.

Particulars which are subject to guarantee shall be clearly marked. Bids lacking information in G.T.P are liable to be

rejected

The Entire units or minimum three functions of RMU shall be enclosed in a single compact metal clad, outdoor

enclosure suitable for all weather conditions. The switchgear/steel gas tank shall be filled with SF6 as per IEC/IS

Standards relative pressure to ensure the insulation and breaking functions. The steel gas tank must be sealed for life

and shall meet the “sealed pressure system” criteria in accordance with the IEC 298 standard. The RMU must be a

system for which no handling of gas is required throughout the 20 years of service life.

The RMU shall have a design such that in the event of an internal arc fault, the operator shall be safe. This should be in

accordance with IEC 298 and relevant Test certificates shall be submitted with the Tender.

The offered switchgear and control gear should be suitable for continuous operation under the basic service

conditions indicated below. Installation should be in normal indoor conditions in accordance with IEC 60694.

Ambient temperature – 10 degree C to + 45 degree C

Relative humidity - up to 95%

Altitude of installation - up to 1000m, IEC 60120

1.3.1 The RMU shall be tested for an internal arc rating of 20 kA for 1 Sec. for 11 KV RMU. Suitable temperature rise

test on the RMU shall be carried out & test reports shall be submitted with tender for technical bid evaluation.

Each switchboard shall be identified by an appropriately sized label, which clearly indicates the functional units and

their electrical characteristics.

The switchgear and switchboard shall be designed so that the position of the different devices is visible to the

operator on the front of the switchboard and operations are visible as well.

The entire system shall be totally encapsulated. There shall be no access to exposed conductors. In accordance with

the standards in effect, the switchboards shall be designed so as to prevent access to all live parts during operation

without the use of tools.

The entire 11 KV RMU are insulated by inert gas (SF6) suitable for operating voltage up to 13.8KV respectively. The 11

KV circuit breakers must be VCB breaker. It is necessary to fit an absorption material in the tank to absorb the


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moisture from the SF6 gas. The SF6 insulating medium shall be constantly monitored via a temperature compensating

gas pressure indicator offering a indication at different temperature ranges, having distinctive RED and GREEN zones

for safe operation.

All the RMUs must be routine tested for the following at factory in India:-

� Micro-ohm test for the assembly inside the tank.

� Circuit breaker analyzer test so as to ensure the simultaneous closing of all poles for VCB.

� SF6 gas leak test.

� Partial Discharge test on the complete gas tank so as to be assure of the proper insulation level and high

product life.

� High voltages withstand.

� Secondary test to ensure the proper functioning of the live line indicators, fault passage indicators and relays.

1.3.2Sulphur Hex fluoride Gas(SF6 GAS)

The SF6 gas shall comply with IEC 376,376A, and 376B and shall be suitable in all respects for use in 11 KV RMUs under

the operating conditions. The SF6 shall be tested for purity, dew point air hydrolysable fluorides and water content as

per IEC 376,376A and 376B and test certificate shall be furnished to the owner indicating all the tests as per IEC 376

for each Lot of SF6 Gas.

DIELECTRIC MEDIUM

SF6 / VCB GAS shall be used for the dielectric medium for 11KV RMUS in accordance with IEC376. It is preferable to fit

an absorption material in the tank to absorb the moisture from the SF6 / VCB gas and to regenerate the SF6 / VCB gas

following arc interruption. The SF6 / VCB insulating medium shall be constantly monitored via a temperature

compensating gas pressure indicator offering a simple go, no-go indication.

General structural and mechanical construction:

The offered RMU should be of the fully arc proof metal enclosed, free standing, floor mounting, flush fronted type,

consisting of modules assembled into one or more units. Each unit is made of a cubicle sealed-for life with SF6 / VCB

and contains all high voltage components sealed off from the environment.

The overall design of the indoor switchgear should be such that front access only is required. It should be possible to

erect the switchboard against a substation wall, with HV and LV cables being terminated and accessible from the front.

The units should be constructed from Minimum 2 mm thick stainless steel sheets. However, Offer with type test

report of pressure withstand test for gas filled compartment with pressure relief device test as per cl. no. 6-103-1 of

IEC 62271-200-2003 can be accepted for 2mm stainless steel tank thickness. The design of the units should be such

that no permanent or harmful distortion occurs either when being lifted by eyebolts or when moved into position by

rollers.


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For outdoor RMUs a weather proofing process shall be carried out. SHEET METAL MUST BE GRIT BLASED /

THERMALLY SPRAYED AND POLYURETHANE PAINTED WITH ABOUT 70 MICRON THICKNESSES, TO ACHIVE

OUTDOOR WORTHINESS AND CORROSION PROOF NESS.

- RMU ENCLOSURE MUST BE SHIELDED AGAINST SOLAR IRRADIATION AND TESTED FOR A

AMBIENT OF 45 DEGREE C WITHOUT DERATING OF THE EQUIPMENT.

The cubicle should be have a pressure relief device. In the rare case of an internal arc, the high pressure caused by the

arc will release it, and the hot gases is allowed to be exhausted out at the bottom / top / rear of the cubicle. A

controlled direction of flow of the hot gas should be achieved.

The switchgear should have the minimum degree of protection (in accordance with IEC 60529)

- IP 67 for the tank with high voltage components

- IP 2X for the front covers of the mechanism

- IP 3X for the cable connection covers

- IP 54 for the outdoor enclosure.

1.4 STANDARDS:

Unless otherwise specified elsewhere in this Specification, the RMU, Switchboard (Switchgear), Load break isolators,

Instrument Transformers and other associated accessories shall conform to the latest revisions and amendments

thereof to the following standards.

1. IEC 60 298/IEC 62 271-200/IS 12729:1988 - General requirement for Metal Enclosed Switchgear

2. IEC60129/IEC62271-102/IS 9921 - Alternating current disconnector’s (Load break isolators) and earthing switch

3. IEC 62 271-100 & 200/IEC 60 056/IS 13118:1991 - Specification for alternating current circuit breaker

4. IEC 62 271-1/IEC 60694 - Panel design, SF6/Vacuum Circuit Breakers

5. IEC 60044-1/IEC 60185/IS 2705:1992 - Current Transformer

6. IEC 60265/IS 9920:1981- High voltage switches.

7. IEC 376 - Filling of SF6 gas in RMU.

8. IEC 60273/IS: 2099 - Dimension of Indoor & Outdoor post insulators i. with voltage > 1000 Volts.

9. IEC 60529/IS 13947(Part-1) - Degree of protection provided by

i. enclosures for low voltage switchgear and

ii. Control gear.

10. Indian Electricity Rules/IS Code

Equipment meeting with the requirements of any other authoritative standards, which ensures equal or better quality

than the standard mentioned above shall also be acceptable. If the equipments, offered by the Bidder conform to

other standards, salient points of difference between the standards adopted and the specific standards shall be clearly

brought out in relevant schedule. In case of any difference between provisions of these standards and provisions of

this specification, the provisions contained in this specification shall prevail. One copy of such standards with authentic

English Translations shall be furnished along with the offer.(Hard copy)

Applicable Standards


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� The RMUs shall be manufactured to the highest quality consistent with best practice and workmanship

and in full accord with the Supplier’s quality assurance plan. The RMUs shall conform to the Indian or IEC

international standards that are applicable. These include the standards listed in Table 1Error! No text of

specified style in document.-1 below.

Table 1Error! No text of specified style in document.-1: Applicable Standards

Standard Description

IS 3427 AC metal enclosed switchgear and control gear for rated voltages above 1 kV and up

to and including 52 kV

IS 12063 Classification of degrees of protection provided by enclosures of electrical

equipment

IS 9920

(Parts 1 to 4) High Voltage Switches

IS 9921

(Parts 1 to 5) Specification for AC disconnectors and earthing switches for voltages above 1000 V

IS 13118 HV AC Circuit Breakers

IS 10601 Dimensions of terminals of HV Switchgear and Control gear

IS 12729 General requirements of switchgear and control gear for voltages exceeding 1000 V

IEC 1330 High voltage/Low voltage prefabricated substations

IEC 60694 Common clauses for MV switchgear standards

IEC 6081 Monitoring and control

IS 2705 Current Transformers

IS 3156 Voltage transformers

IS 8686 Specification for Static Protective Relays

IEC 62271-

200 Standards for high voltage metal clad switchgear up to 52 KV.

INDIAN

ELECTRCIATY

REGULATION

2011

This is to be as per Central Electricity Authority (Safety Requirement for

Construction, Operation & Maintenance of Electrical Plants and Electric Lines)

Regulations, 2011

1.5 THE STANDARDS MENTIONED ABOVE ARE AVAILABLE FROM:

IEC - (INTERNATIONAL ELECTRO-TECHNICAL COMMISSION, BUREAU CENTRAL DE LA COMMISSION, ELECTRO

TECHNIQUE INTERNATIONAL, 1, RUE DE VEREMBE, GENEVA, SWITZERLAND.)

ISO - INTERNATIONAL STANDARD ORGANISATION

1.6 SPECIFIC REQUIREMENTS IN RMU:-

1.6.1 CLIMATE CONDITIONS


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The climatic conditions under which the equipment should operate satisfactory are as under:

� Maximum ambient air temperature :40-45 deg. C

� Minimum ambient air temperature :10 deg.C

� Maximum daily average ambient air temperature :40 C

� Maximum humidity :100%

� Altitude above M.S.L. (maximum) :1000 metres

� Average annual rainfall(mm) :925

� Max. wind pressure(Kg/sq.m) :200

� Seismic level(Horizontal accn.) :0.3 g

� Iso-ceraunic level(Days per Year) :50

� Average thunder storm days per annum :50

1.6.2 Distribution Network Electrical Parameters

The main parameters of the distribution network are as follows:

� Nominal system voltage: 11 kV (rms)

� Highest system voltage: 12 kV (rms)

� Number of phases: 3

� Frequency: 50 Hz

� Variation in frequency: 49.5 Hz to 50.5 Hz

� Type of earthing: Solid

� Power frequency withstand voltage: 28 kV

� Basic impulse withstand voltage : 75 kV

1.7 RMU OUTDOOR METAL CLAD ENCLOSURE.

The RMU enclosure must be a metallic, it shall follows an industrialized process of manufacturing. The RMU and

combination shall be tropicalised and outdoor metal enclosed type. The RMU metal parts shall be of high thickness,

high tensile steel which must be grit/short blasted, thermally sprayed with Zinc alloy, phosphate or should follow the 7

tank pre-treatment process and be subsequently painted with polyurethane based powder paint. The overall paint

layer thickness shall be not less than 80 microns.

The rating of enclosure shall be suitable for operation on three phase, three wire, 11 KV, 50 cycles, A.C. System with

short-time current rating of 20KA for 3 seconds for 11 KV with RMU Panels.


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The enclosure should have two access doors one for the operation and relay monitoring and other for the cable

access. Both the doors should have the locking facility to prevent the access to operating mechanism to avoid

unauthorized operating of RMU and relay.

RMU Design Features

All design features of the proposed RMU, as described in the supplier’s bid and in the bid’s reference materials, shall

be fully supported by the equipment actually delivered. The key design features include those that relate to:

� Maintainability, expandability, and life span

� Ability to operate in severe outdoor environmental conditions.

� Immunity to electrical stress and disturbance.

� Acceptable insulation properties.

� Convenient FRTU interconnection features.

INDOOR RMU

1. MODULAR DESIGN, PANEL TYPE WITH FRONT CABLE ACCESS.

2. RMU MUST BE MADE OF ROBOTICALLY / TIG / MIG WELDED STAINLESS STEEL.

3. Offered RMU must be extensible.

OUT DOOR RMU

1. Stainless steel enclosure for OUT DOOR RMU application. The manufacturers shall conform the normal

current ratings mentioned in GTP at 45 deg. Ambient without derating or as per IEC Standard

2. Enclosure with I.P.54 standard protection.


4. Cable boxes shall be on Front/ side sides.

5. RMU ENCLOSURE MUST BE SHIELDED AGAINST SOLAR IRRADIATION AND TESTED FOR AMBIENT OF 45

DEGREE C. The manufacturers shall conform the normal current ratings mentioned in GTP at 45 deg. Ambient

without derating, however, design for higher ambient temperature than 45 degree may be admissible.

1.8 TAKE OFF TERMINAL UNITS FOR AUTOMATION:

The RMU should be provided with necessary take off terminal units for automations, located in the front recesses / LV

cubical of the RMU. The connectivity to the FRTU for SCADA purpose shall be provided. Refer Annexure-1 for general

arrangement of the termainals.

1.9 ISOLATORS (LOAD BREAK TYPE)

The load break isolators for Incoming and Outgoing supply must be provided. These should be fully insulated by SF6

gas. The load break isolators shall consist of 630 Amp fault making/load breaking spring assisted ring switches, each

with integral fault making earth switches. The switch shall be naturally interlocked to prevent the main and earth

switch being switched “ON‟ at the same time. The selection of the main and earth switch is made by a lever on the

facia, which is allowed to move only if the main or earth switch is in the off position. The load break isolators should

have the facility for remote operation. Each load break switch shall be of the triple pole, simultaneously operated,

automatic type with quick break contacts and with integral earthing arrangement.


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The isolating distance between the OFF and the ON position in the isolator should be sufficient to withstand dielectric

test as per IS/IEC, so as to have enough isolating distance for ensuring safety during DC injection for Cable testing.

Load break switch should have the following

� Motor operated 12 KV, 630A Load Break switch and manually operated Earthing Switch with making capacity.

� “Live Cable” LED Indicators thru Capacitor Voltage Dividers mounted on the bushings.

� Mechanical ON/OFF/EARTH Indication

� Anti-reflex operating handle

� Cable Testing facility without disconnecting the cable terminations, cable joints and terminal protectors on the

bushings.

Cable terminations

� Cable boxes suitable for 1 X 3C x 300 sq mm XLPE Cable with right angle Cable Termination Protectors.

1.10 EARTHING OF ISOLATORS AND BREAKERS (EARTH SWITCH)

Necessary arrangements are provided at Load break isolators Breaker for selecting Earth position. Mechanical

interlocking systems shall prevent the RMU function from being operated from the “ON” to “Earth On” position

without going through the “OFF” position.

1.11 DISTRIBUTION TRANSFORMER/FEEDER BREAKER (VACUUM)

The VCB breaker for the controlling of DT/Feeder Breaker must be provided inside welded stainless steel SF6

gas tank with the outdoor metal clad enclosure. The VCB circuit breaker must be a spring assisted three positions with

integral fault making earth switch. The selection of the main/earth switch lever on the facia, which is allowed to move

only if the main or earth switches is in the off position.

The manual operation of the circuit breaker shall not have an effect on the trip spring. This should only be discharged

under a fault (electrical) trip; the following manual reset operation should recharge the trip spring and reset the circuit

breaker mechanism in the main off position.

The circuit breaker shall be fitted with a mechanical flag, which shall operate in the event of a fault (electrical) trip

occurring. The “tripped” flag should be an unambiguous colour differing from any other flag or mimic.

Both the circuit breaker and ring switches are operated by the same unidirectional handle.

The protection on the circuit breaker shall comprise of the following components:-

- 3 class X protection CT‟s,

- a low burden trip coil and

- a self powered (No external DC or AC source required) IDMT


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protection relays (Numeric/Micro processor based) 3 x over current and earth fault element shall be Definite Time

type relay . The protection system should be suitable for protecting transformers of rated power from 250 KVA on

wards. The relay should be housed within a pilot cable box accessible.

Circuit Breaker should have the following:

- Motor operated 200 A / 630A SF6 insulated Vacuum circuit breaker and Ear thing Switch with making capacity

- Mechanical tripped on fault indicator

- Auxiliary contacts 4NO and 4NC

- Anti-reflex operating handle

- “Live Cable” LED Indicators thru Capacitor Voltage Dividers mounted on the bushings.

- O/C + E/F self powered relay

- Shunt Trip circuit for external trip signal

- Mechanical ON/OFF/EARTH Indication

- Cable boxes suitable for 1 X 3C x 300 sq mm XLPE Cable with right angle Cable Termination / protectors / boots

TECHNICAL DATA

1 Ring Main Unit, Electrical data

Electrical data and service conditions

Rated voltage KV 12/15.5 KV

1 Power frequency withstand voltage KV 28 / 35

2 Impulse withstand voltage KV 75 / 95

3 Rated frequency Hz 50

4 Rated current busbars A 630

5 Rated current (cable switch) A 630

6 Rated current (T-off) A 200 / 630

Breaking capacities:

7 active load A 630

8 closed loop (cable switch) A 630

9 off load cable charging (cable switch) A 135

10 earth fault (cable switch) A 200


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11 earth fault cable charging (cable switch) 115

12 short circuit breaking current (T-off circuit

breaker)

kA 20 / 21

13 Rated making capacity kA 52

14 Rated short time current 3 sec. kA 20 / 21

Ambient temperature:

15 Maximum value °C + 45

16 Maximum value of 24 hour mean °C + 40

17 Minimum value °C 0

18 Altitude for erection above sea level4 m ...1000

19 Relative humidity Max 95%

2 Ring Main Unit Technical data (11KV/22KV)

No. General data, enclosure and dimensions

1 Standard to which Switchgear complies IEC

2 Type of Ring Main Unit Metal Enclosed, Panel type, Compact

Module.

3 Number of phases 3

4 Whether RMU is type tested Yes

5 Whether facility is provided with pressure relief Yes

6 Insulating gas SF6

7 Nominal operating gas pressure

1.4 bar @ 20° C. However offer with

Nominal operating gas pressure shall be as

per manufacturer standard and suitable to

satisfy the rated dielectric strength can be

accepted

8 Gas leakage rate / annum 0.075%

9 Expected operating lifetime 30 years

10 Whether facilities are provided for gas monitoring Yes, temperature compensated manometer

can be delivered


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11 Material used in tank construction Stainless steel sheet, minimum 2 mm

No. Operations, degree of protection and colours

1 Means of switch operation separate handle

2 Means circuit breaker operation separate handle and push buttons

3 Rated operating sequence of Circuit Breaker O - 3min-CO-3min-CO

4 Total opening time of Circuit Breaker approx. 45ms

5 Closing time of Circuit Breaker approx. 40ms

6 Mechanical operations of switch (co) 1000

7 Mechanical operations of CO earthing switch 1000

8 Mechanical operations of circuit breaker (co) 2000

9 Principle switch / earth switch 3 position combined switch / earth switch

Degree of protection:

10 High Voltage live parts, SF6 / VCB tank IP 67

11 Front cover mechanism IP 2X

12 Cable covers IP 3X

13 Outdoor Enclosure IP 54

Colours:

14 Front cover

15 Side and cable cover

1.12 BUSHINGS

The units are fitted with the standardized bushings that comply with IEC standards. All the bushings are the same

height from the ground and are protected by a cable cover.

1.13 CABLE BOXES

All the cable boxes shall be air insulated suitable for dry type cable terminations and should have front/side access.

The cable boxes at each of the two ring switches should be suitable for accepting HV cables of sizes 3c x 300 sq.mm

and circuit breaker cable suitable up to 3c x 300 sq.mm. The cable boxes

for an isolator in its standard design should have sufficient space for connecting two cables per phase .Necessary Right

angle Boot should be supplied to the cable terminations .The type of the Right angle Boot should be cold applied

insulating Boot.

1.14 CABLE TESTING FACILITY

It shall be possible to test the cable after opening the cable boxes. The cable boxes should open only after operation of

the earth switch. Thus ensuring the earthing of the cables prior to performing the cable testing with DC injection.

1.15 VOLTAGE INDICATOR LAMPS AND PHASE COMPARATORS

The RMU shall be equipped with a voltage indication to indicate whether or not there is voltage on the cable. There

should be a facility to check the synchronization of phases with the use of external device. It shall be possible for the


Page 15 of 95

each of the function of the RMU to be equipped with a permanent voltage indication as per IEC 601958 to indicate

whether or not there is voltage on the cables.

1.16 EXTENSIBLE

Each combination of RMU shall have the provision for extension by load break isolators / breakers in future, with

suitable accessories and necessary Bus Bar. The equipment shall be well designed to provide any kind of extension /

trunking chamber for connecting and housing extensible Busbars. Extensible isolators and circuit breakers shall be

individually housed in separate SF6 gas enclosures. Multiple devices inside single gas tank / enclosure will not be

acceptable. In case of extensible circuit breakers, the Breaker should be capable of necessary short circuit operations

as per IEC at 20 KA, and the Breaker should have a rated current carrying

capacity of 200 A to 630 A.

1.17 WIRING & TERMINALS:

The wiring should be of high standard and should be able to withstand the tropical weather conditions. All the wiring

and terminals (including take off terminals for future automation, DC, Control wiring), Spare terminals shall be

provided by the contractor. The wiring cable must be standard single-core non-sheathed, Core marking (ferrules),

stripped with non-notching tools and fitted with end sleeves, marked in accordance with the circuit diagram with

printed adhesive marking strips.

The wiring should be of high standard and should be able to withstand the tropical weather conditions. All wiring shall

be provided with single core multi-strand copper conductor wires with P.V.C insulation.

The wiring shall be carried out using multi-strand copper conductor super flexible PVC insulated wires of 650/1100V

Grade for AC Power, DC Control and CT circuits. Suitable colored wires shall be used for phase identification and

interlocking type ferrules shall be provided at both ends of the wires for wire identification. Terminal should be

suitably protected to eliminate sulphating. Connections and terminal should be able to withstand vibrations. The

terminal blocks should be stud type for controls and disconnecting link type terminals for CT leads with suitable spring

washer and lock nuts.

Flexible wires shall be used for wiring of devices on moving parts such as swinging Panels (Switch Gear) or panel doors.

Panel wiring shall be securely supported, neatly arranged readily accessible and connected to equipment terminals,

terminal blocks and wiring gutters. The cables shall be uniformly bunched and tied by means of PVC belts and carried

in a PVC carrying trough.

The position of PVC carrying trough and wires should not give any hindrance for fixing or removing relay casing,

switches etc., Wire termination shall be made with solder less crimping type of tinned copper lugs. Core identification

plastic ferrules marked to correspond with panel wiring diagram shall be fitted with both ends of each wire. Ferrules

shall fit tightly on the wire when disconnected. The wire number shown on the wiring shall be in accordance with the

IS.375.

All wires directly connected to trip circuits of breaker or devices shall be distinguished by addition of a red color

unlettered ferrule.

Inter-connections to adjacent Panels (Switch Gear) shall be brought out to a separate set of Terminal blocks located

near the slots or holes to be provided at the top portion of the panel. Arrangements shall be made for easy

connections to adjacent Panels (Switch Gear) at site and wires for this purpose shall be provided and bunched inside

the panel. The bus wire shall run at the top of the panel.


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Terminal block with isolating links should be provided for bus wire. Ateast 10% of total terminals shall be provided as

spare for further connections. Wiring shall be done for all the contacts available in the relay and other equipment and

brought out to the terminal blocks for spare contacts. Color code for wiring is preferable in the following colours.

� Voltage supply : Red, Yellow, Blue for phase and Black for Neutral

� CT circuits : similar to the above

� DC circuits : Grey for both positive and negative

� 250V AC circuits : Black for both phase and neutral

� Earthing : Green

The wiring shall be in accordance to the wiring diagram for proper functioning of the connected equipment. Terminal

blocks shall not be less than 650V grade and shall be piece-molded type with insulation barriers.

The terminal shall hold the wires in the tight position by bolts and nuts with lock washers. The terminal blocks shall be

arranged in vertical formation at an inclined angle with sufficient space between terminal blocks for easy wiring.

The terminals are to be marked with the terminal number in accordance with the circuit diagram and terminal

diagram. The terminals should not have any function designation and are of the tension spring and plug-in type.

Clear empty Space shall be mandatorily provided in RMU Panel for mounting FRTU Panel. Dimensions details of

required space for FRTU are about 1500 mm H x 600 mm W x 300 mm D. 230V AC Supply for charging of FRTU battery

should be available. The Aux supply will be taken through the PT provided for metering in RMU. We require 230V AC

and not 110V AC. FRTU will require power up to 500 VA depending upon RMU configuration. The PT must have

sufficient burden for meeting the aforesaid requirement also for battery charging.

1.18 EARTHING

The RMU outdoor metal clad, Switch Gear, Load break isolators, Vacuum circuit breakers shall be equipped with an

earth bus securely fixed along the base of the RMU.

The size of the earth bus shall be made of IEC/IS standards with tinned copper flat for RMU and M.S.Flat for

Distribution Transformer, earth spike and neutral earthing. Necessary terminal clamps and connectors shall be

included in the scope of supply.

All metal parts of the switchgear which do not belong to main circuit and which can collect electric charges causing

dangerous effect shall be connected to the earthing conductor made of copper having CS area of minimum 75 mm.

Each end of conductor shall be terminated by M 12/equivalent quality and type of terminal for connection to earth

system installation. Earth conductor location shall not obstruct access to cable terminations.

The following items are to be connected to the main earth conductor by rigid or copper conductors having a minimum

cross section of 75 mm (a) earthing switches (b) Cable sheath or screen (c) capacitors used in voltage control devices,

if any.

The metallic cases of the relays, instruments and other panel mounted Equipment‟s shall be connected to the earth

bus by independent copper wires of size shall be made of IEC/IS standards. The colour code of earthing wire shall be

green. Earthing wires shall be connected on the terminals with suitable clamp connectors and soldering shall not be

permitted.


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1.19 ACCESSORIES & SPARES:

The following spares and accessories shall be supplied along with the main equipments at free of costs. This shall not

be included in the price schedule.

1. Charging lever for operating load break isolators & circuit breaker of each RMU.

2. The pressure gauges indications - 1 numbers

Provision shall be made for padlocking the load break switches/ Circuit breaker, and the earthing switches in either

open or closed position with lock & master key.

1.20 TESTING OF EQUIPMENT & ACCESSORIES:

Provision for testing CTs,PTs, Relays, Breakers and Cables shall be made available. Procedure and schedule for

Periodical & Annual testings of equipments, relays, etc. shall be provided by the supplier.

1.20.1 TYPE TEST

The Tenderers should, along with the tender documents, submit copies of all Type test certificate of their make in full

shape as confirming to relevant ISS/IEC of latest issue obtained from a International/National Govt. Lab/Recognized

laboratory.

The above type test certificates should accompany the drawings for the materials duly signed by the institution who

has type test certificate. The details of type test certificate as per Schedule F.

1.20.2 ACCEPTANCE AND ROUTINE TESTS

All acceptance and routine tests as stipulated in the latest IEC- shall be carried out by the supplier in the presence of

DISCOM’s representative. The supplier shall give at least 7 days advance intimation to the DISCOM to enable them to

depute their representative for witnessing the tests. The partial discharge shall be carried out as routine test on each

and every completely assembled RMU gas tank and not on a sample basis. As this test checks and guarantees for the

high insulation level and thus the complete life of switchgear.

1.20.3 ADDITIONAL TESTS

The DISCOM reserves the right for carrying out any other tests of a reasonable nature at the works of the

supplier/laboratory or at any other recognized laboratory/research institute in addition to the above mentioned type,

acceptance and routine tests at the cost of the Board to satisfy that the material complies with the intent of this

specification.

1.20.4 PRE-COMMISSIONING TESTS

All the pre-commissioning tests will be carried out in the presence of the DISCOM’s testing engineer and necessary

drawing manual and periodical test tools shall be arranged to be supplied.

During the above tests the contractor representative should be present till the RMUs are put in to service.

1.21 INSPECTION:


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The inspection may be carried out by the DISCOM at any stage of manufacture. The supplier shall grant free access to

DISCOM’s representative at a reasonable time when the work is in progress. Inspection and acceptance of any

equipment under this specification by the DISCOM shall not relieve the supplier of his obligation of furnishing

equipment in accordance with the specification and shall not prevent subsequent rejection if the equipment is found

to be defective.

The supplier shall keep the DISCOM informed in advance, about the manufacturing programme so that arrangement

can be made for inspection. The DISCOM reserves the right to insist for witnessing the acceptance/routine testing of

the bought out items. The DISCOM has rights to inspect the supplier’s premises for each and every consignment for

type & routine test.

No material shall be dispatched from its point of manufacture unless the material has been satisfactorily inspected

and tested / unless the same is waived by the DISCOM in writing.

1.21.1 : QUALITY ASSURANCE PLAN:

The bidder shall invariably furnish following information along with his offer / in case of event of order.

I. Statement giving list of important raw materials including but not limited to

a) Contact material

b) Insulation

c) Sealing material

d) Contactor, limit switches, etc. in control cabinet.

Name of sub-suppliers for the raw materials, list of standards according to which the raw materials are tested, list of

test normally carried out on raw materials in presence of Bidder’s representative, copies of test certificates.

II. Information and copies of test certificates as in (I) above in respect of bought out accessories & raw materials.

III. List of areas in manufacturing process, where stage inspections are to be carried out.

IV. Normally carried out for quality control and details of such tests and inspections.

V. Special features provided in the equipment to make it maintenance free.

VI. List of testing equipment available with the Bidder for final testing of RMUs and associated combinations vis-à-vis

the type, special, acceptance and routine tests specified in the relevant standards. These limitations shall be very

clearly brought out in the relevant schedule i.e. schedule of deviations from specified test requirements. The supplier

shall, within 15days from the date of receipt of Purchase Order submit following information to the DISCOM.

a) List of raw materials as well bought out accessories and the names of sub-suppliers selected from those furnished

along with offer.

b) Necessary test certificates of the raw material and bought out accessories.

c) Quality Assurance Plan (QAP) with hold points for DISCOM’s inspection. The quality assurance plan and hold points

shall be discussed between the DISCOM and supplier before the QAP is finalized.


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The supplier shall submit the routine test certificates of bought out items and raw material, at the time of routine

testing of the fully assembled breaker.

1.22 TRAINING:

The supplier shall give rigorous training to the engineers & staff for 2 days in attending trouble shooting and

maintenance.

1.23 SCADA CONNECTIVITY:

Provision shall be made in all the RMUs with necessary take off terminal units for automations and connectivity with

FRTU. The all RMUs shall be motorized type and compatible for SCADA operation. All the I/O signals need to be

brought to the Terminal Strip on a Din Rail, also the Din Rail should have space to mount the MFT’s provided by SIA.

All the DI’s, AI’s and DO’s should be provided as potential free and control contacts. The CT/PT should provide

metering grade core for connecting MFT provided with FRTU. The RMU will also supply 230VAC 500VA for FRTU. Refer

Annexure-1.

The RMU should be provided with provision of following minimum signals available at separate SCADA terminal box.

Minimum signals for SCADA/DMS - to be wired

to Separate TBs

CB close / open potential free contacts

LBS close / open potential free contacts

LBS & CB Earth Switch close /open potential free contacts

CB Test/Service Position potential free contacts

Spring charge Status indication potential free contacts

SF6 gas pressure low potential free contacts

O/C Operated potential free contacts

E/F Operated potential free contacts

Local/Remote potential free contacts

Common Power Supply Healthy potential free contacts

Motor MCB Healthy Status potential free contacts

Battery charger Fail potential free contacts

RMU Door Open potential free contacts

CB Trip Coil Healthy potential free contacts

CT & PT For SCADA Metering


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FPI Control FPI remote resetting for SCADA

CB control Control from SCADA

LBS Control Control from SCADA

1.24 DOCUMENTATION and DRAWINGS

All drawings shall conform to relevant International Standards Organization (ISO) Specification. All drawings shall be in

ink and suitable for microfilming.

The tenderer shall submit along with his tender dimensional general arrangement drawings of the equipments,

illustrative and descriptive literature in triplicate for various items in the RMUs which are all essentially required for

future automation.

I. Schematic diagram of the RMU panel

II. Instruction manuals

III. Catalogues of spares recommended with drawing to indicate each items of spares

IV. List of spares and special tools recommended by the supplier.

V. Copies of Type Test Certificates as per latest IS/IEC.

VI. Drawings of equipments, relays, control wiring circuit, etc.

VII. Foundation drawings of RMU and D.T.Structure.

VIII. Dimensional drawings of each material used for item VII.

IX. Actual single line diagram of RMU/RMUs with or without Extra combinations shall be made displayed on the

front portion of the RMU so as to carry out the operations easily.

The following should be supplied to each consignee circle/town along with the initial supply of the equipments

ordered.

a. Copies of printed and bound volumes of operation, maintenance and erection manuals in English along with

the copies of approved drawings and type test reports etc.

b. Sets of the manuals as above shall be supplied to the Chief Engineer/Distribution. A soft copy of the all

Technical and Drawing furnished in a CD

1.25 NAME PLATE:

Each RMU and its associated equipments shall be provided with a nameplate legible and indelibly marked with at least

the following information.

a. Name of manufacturer


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b. Type, design and serial number

c. Rated voltage and current

d. Rated frequency

e. Rated symmetrical breaking capacity

f. Rated making capacity

g. Rated short time current and its duration

h. Purchase Order number and date

i. Month and Year of supply

j. Rated lighting impulse withstand voltage

k. Feeder name (Incoming and Outgoing), DTs Structure name, 11000 Volts Dangers etc.

NOTE:

I) THE WORD RATED NEED NOT APPEAR ON THE NAME PLATE. RECOGNIZED ABBREVIATIONS MAY BE USED TO

EXPRESS THE ABOVE PARTICULARS.

II) WHETHER THE CIRCUIT BREAKER IS FITTED WITH CLOSING/TRIPPING DEVICES NECESSITATING AN AUXILIARY

SUPPLY SHALL BE STATED EITHER ON THE CIRCUIT BREAKER NAME PLATE OR ANY OTHER ACCEPTABLE

POSITION.

1.26 FAULT PASSAGE INDICATORS (FPI):

These shall facilitate quick detection of faulty section of line. The fault

indication may be on the basis of monitoring fault current flow through the device.

The unit should be self-contained requiring no auxiliary power supply. The FPI shall

be integral part of RMU. The FPI shall have LCD/LED display, automatic reset

facility. FPI Reset from SCADA will be through momentary closure of a potential free contact from FRTU.

The sensors to be bushing mounted. The number of FPI should be put in all the three phases of the outgoing branch of

the RMUs

FPI should have suitable connectivity with the FRTUs for the SCADA purpose.

The FPI inside the RMU may be non communicable and hard wired to the TB for the signals

Fault Passage indicator OK

Fault Passage indicator operated

1.27 TROPICALISATION

Due regard should be given to the climatic conditions under which the equipment is to work. Ambient temperatures

normally vary between 20 deg C and 40 deg C, although direct sun temperature may reach 45 deg C. The climate is


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humid and rapid variations occur, relative humidity between 60% and 95% being frequently recorded, but these values

generally correspond to the lower ambient temperatures. The equipment should also be designed to prevent ingress

of vermin, accidental contact with live parts and to minimize the ingress of dust and dirt. The use of materials which

may be liable to attack by termites and other insects should be avoided.

1.28 Motorization :

All the functions within the RMU i.e Isolators/Breakers should be fitted with motor mechanism and closing coil making

it suitable to make it on from remote.( However, manual mechanism should be possible in case of failure/ non working

of motor)

Other Accessories (required with RMU) :-

a) Shunt Trip Coil ( Coil voltage shall be indicated later on)

b) Battery & Battery Charger.

c) 4NO+4NC auxiliary contacts.

1.29 Metering:

Multifunction Energy meter shall be provided by DISCOMS with, of accuracy class of 0.5 at incoming isolator of all

RMUs. The Metering CTs and PTs of suitable rating shall be

provided and wired in SCADA terminal TBs.

1.30 TECHNICAL SPECIFICATION FOR RMU

1.30.1 11KV Bus Bar

I. Current Carrying Capacity : 630 Amps.

II. Short time rating current for 3 secs. : 20 KA for 11kv

III. Insulation of bus bar : SF6

IV. Bus bar connections : Anti-oxide grease

1.31 PARAMETERS FOR SWITCH GEAR OF DT AND LOAD BREAK ISOLATORS

I. Type : Metal enclosed

II. No of Phases : 3

III. No. of poles : 3

IV. Rated voltage :12 KV

V. Operating voltage :11 KV(+10% to -20%)

VI. Rated lightning impulse withstand voltage :75 KV

VII. Rated power frequency withstand voltage :28 KV

VIII. Insulating gas :SF6

IX. Rated filling level for insulation :As Per IEC.


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Max.permissible site altitude at the above gas pressures : 1000m

(The operating pressure has to be adjusted for greater altitudes)

Isolating distance between ON and OFF position in isolator :80 mm (min).

Rated short time current :20 KA.for 11kv

Rated short time :3s

Rated peak withstand current :50 KA.

No of operations in Short circuit :15Nos (minimum)

Operating mechanism: Circuit breaker with spring assisted anti reflex mechanism.

Rated current (Bus): :630 A

Rated current (breaker) :200 A

Circuit Breaker interrupter :SF6 insulated VCB

Rated frequency : 50 Hz

Rated operating sequence :O-3min- CO

Number of mechanical/Remote operations for earthing : As per IEC

& Ring switches & Number of mechanical/ Remote operations for circuit breakers 60298

1.32 PRINCIPAL FEATURES

Sr.

No

DESCRIPTION Breaker

1 Circuit label Yes

2 Mimic diagram Yes

3 Supply voltage indication Yes

4 Current Transformer Yes

5 Self Powered based Microprocessor based IDMT

Relay (3OL)/EL

Yes

6 Anti - Reflexing Relay Yes

7 Interlock to defeat the operation of the line side

earthing when the line side isolator is ON.

Yes

8 Interlock to defeat the operation of the earthing

when the breaker is in service position and is ON.

Yes

9 Breaker ON/OFF indication Yes

10 Spring Charge indication / Spring assisted

mechanism.

Yes

11 Fault Tripping indication Yes

12 Bus bar end caps Yes


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13 Whether the SF6 gas pressure gauge indicator and

filling arrangement.

Yes

14 Whether the spring assisted mechanism with

operating handle for ON/OFF.

Yes

15 Whether the earth positions with arrangement for

padlocking in each position and independent

manual operation with mechanically operated

indicator are provided

Yes

16 RMUs are provided with necessary take off

terminals for future automation.

Yes

1.33 Earthing switch for 11 KV Line side Isolation and DT

Rated short time current : 20 KA.for 11kv.


Rated peak withstand current :50 KA

Interlocking facility:

1) Between 11 KV Line side isolator “ON”&Earthing.

2) Between 11 KV DT side breaker on close condition &earthing

1.34 Current Transformers for breaker

CT Type : Tape wound

CT Description : The CTs of breaker shall be Suitable for sensing the minimum

primary variable current in the order of 10-100 A and the secondary current for the CT is 1 A. The CT

shall be housed in outside SF6 chamber for testing and Maintenance

Accuracy Class :class X/5P10 protection

Rated burden : Suitable for self powered relay and metering.

PART A&B: TECHNICAL SPECIFICATION FOR OUTDOOR 22 KV RING MAIN UNIT

SWITCHGEAR

1.1 GENERAL:

1.1.1 All equipment and material shall be designed manufactured and tested in

accordance with the latest applicable IEC standard.

1.1.2 Equipment and material conforming to any other standard, which ensures equal or

better quality, may be accepted. In such case copies of English version of the

standard adopted shall be submitted.

1.1.3 The electrical installation shall meet the requirement of Indian Electricity Rules-1956

as amended up to date; relevant IS code of practice and Indian Electricity Act-1910.

In addition other rules and regulations applicable to the work shall be followed. In case any discrepancy ,the

most stringent and restrictive one shall be binding.


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1.1.4 The high-tension switchgear offered shall in general comply with the latest issues

including amendments of the following standards but not restricted to them.

1.2 SCOPE:

Design, Engineering, Manufacture, assembly, Stage testing, inspection and testing before supply and delivery at site,

Erection, Installation, testing & Commissioning of Ring Main units outdoor type SF6 filled , with various combinations

of load break isolators & breakers. The scope includes Supply, Erection, testing and commissioning of outdoor type

RMU with necessary take off terminal units for future automations contains load break isolators, breaker and

associated accessories, equipments. (including civil works and earthing- Erection of earthing by using GI strip

(minimum 35 mm strip) with earthing plate including cost of coal/salt to RMU). The Installation of 11KV Outdoor SF6

Insulated RMU covering erection,testing and commissioning with associated equipment including civil work of RMU,

drawing and Bom(Bill of Material) of civil work submit by bidder along with technical details.

The RMUs should be provided with necessary take off terminal units for future automations and all these units should

be shielded in a outdoor metal-body for making them suitable for outdoor use. The insulation/dielectric media inside

the stainless steel welded tank should be SF6 gas. The RMUS should be Modular ,extensible type on both sides with

provision of attaching/connecting with SNAP FIT arrangement W/o External Busbars additional load break switches

and circuit breakers in future whenever required. Alternatively Extension shall be possible by adding trunking

chambers and required accessories or by plug-in bushing type arrangement.

The Package scope of work shall include survey, design, manufacture, FAT and delivery,

installation and commissioning of new SCADA enabling equipments of new “SCADA-Ready”

The RMU should have compatibility with OPEN PROTOCOL SCADA system.

Ring Main Units capable of being monitored and controlled by the SCADA/DMS. The RMU should have the castle lock

for avoiding dual supply and safety purpose.

Where relevant, the RMU scope of work shall be coordinated with the work to be carried out under the project’s other

construction packages & associated materials to the designated destinations as per this tender specification and Bill of

quantities. Includes supply of relevant 22KV cable termination kits per this tender Specification.

Each RMU shall include its own power supply unit (including auxiliary power transformer, batteries, and battery

charger), which shall provide a stable power source for the RMU. The RMUs will be connected to the FRTU which will

be procured, supplied and installed as a part of Part A of R-APDRP. The RMU will also supply 230VAC 500VA for FRTU.

Refer Annexure-1.

FRTU, MODEM, Power and I/O cable interface between FRTU and Control panel of RMU/sectionaliser are excluded in

the scope of supply and these items will be provided by DISCOM/SIA.

Each new RMU shall be equipped with main-line load break switches and a fault passage indicator

(FPI). Furthermore, to protect each of its lateral / transformer feeders, it shall be equipped with a corresponding set of

circuit breakers and self-powered numerical relays. The RMU shall include potential-free contacts and control contacts

so as to connect to SCADA/DMS via FRTUs, so as to:


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� Monitor and control the open/closed status of the RMU circuit breakers and load break switches.

� Monitor the local/remote position of RMU motorised (in case if failure of motor) manually-operated

switches that can be used to enable and disable remote monitoring.

� Monitor the health of the power supply, which will include battery failure and low voltage indications.

� Monitor the open/closed status of RMU earthing switches.

� Monitor the open/closed status of RMU enclosure doors in case of Hinge doors.

� Monitor for low SF6 gas pressure indication.

� Monitor for circuit breaker relay operations.

� Monitor for indication of main-circuit fault detected by the RMU’s FPI.

1.2.1 Configurations Required:-

22 KV RMU

a) 2-Way , 22 KV Gas (SF6) Insulated RMU with One 630A load break switches

and One SF6 Insulated VCB of suitable rating -

b) 3-way , 22 KV ,Gas (SF6) Insulated RMU with 2Nos 630A load break switch


c) 4-way ,22 KV Gas (SF6) Insulated RMU with 2Nos 630A Load break switches


d) 5-way , 22 KV ,Gas (SF6) Insulated RMU with 2Nos 630A load break switch


e) 6-way ,22 KV Gas (SF6) Insulated RMU with 3Nos 630A Load break switches


PLS NOTE: THE NOMINAL CURRENT RATING OF VCB SHALL BE ACCORDING TO LOAD OF THE FEEDER AND

ACCORDINGLY SUITABLE RELAY SHALL BE PROVIDED AND ANY CHANGE IN COMBINATION/CONFIGURATION SHALL

BE EXECUTED WITH THE APPROVAL OF CHIEF ENGINEER OF RESPECTIVE DISCOM.

1.1 This Specification provides for design, manufacture, inspection and testing before dispatch, packing and

delivery F.O.R.(Destination) of SF6 insulated RMUs with necessary take off terminal units for future automations,

compatible with SCADA system other accessories and auxiliaries equipment and mandatory spares, described herein

and required for their satisfactory operation.


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1.2. The objective of the RMUs is for extremely small construction width, compact, maintenance free, independent

of climate, easy installation, operational reliability, Safe and easy to operate, minimum construction cost, minimum

site work and minimum space requirement.

1.3. The RMUs shall conform in all respects to high standards of Engineering design, workmanship and latest

revisions of relevant standards at the time of offer.

RMU to be installed on Plinth Erection of plinth with cost of cement etc as per below requirement Plinth size

minimum 5’x4’x2’ or as per required Cement ratio 1: 2 : 4 ;Weight of RMU 510 kg to 1000 kg.

1.4. The type of the 22 KV circuit breaker shall be VCB and insulating medium for load break isolators, Earth switch,

22 KV Buses and other associated equipments should be SF6 gas.

� Necessary current sensors / transformers for protection and metering (wherever required).

� All necessary dry (potential-free) contacts for indications relevant to RMU monitoring status and control.

� A PT Panel including auxiliary power transformer for measurement of system voltage and for charging the

batteries.

� Battery and battery charger, to provide stable as per motor rating, 24 VDC, power for the RMU’s motors.

� Capacitor voltage dividers serving live-line cable indicators.

1.3 GENERAL:

The Ring Main Unit shall be installed at 22 KV junction points to have continuous supply by isolating faulty sections.

The RMU shall be extensible on both sides and consists of the following combinations of load break switches and

Circuit breakers for a nominal voltage of 24 KV using SF6 gas as insulating and Vacuum as arc quenching medium.

The RMU and combination shall be tropicalised and outdoor metal enclosed type. The RMU metal parts shall be of

high thickness, high tensile steel which must be grit/short blasted, thermally sprayed with Zinc alloy, phosphate or

should follow the 7 tank pre-treatment process and be subsequently painted with polyurethane based powder paint.

The overall paint layer thickness shall be not less than 80 microns.

Relevant IE rules for clearances, safety and operation inside the enclosure shall be applicable. The enclosure shall be IP

54 and type tested for weather proof at EREDA/CPRI.

All live parts except for the cable connections in the cable compartments shall be insulated with SF6 gas. The SF6 gas

tank shall be made of robotic or TIG or MIG or Laser or manually welded stainless steel, to have the best weld quality.

The gas cubicle shall be metal enclosed with stainless Steel of thickness as per IEC tested/ designed so as to provide

safety and to avoid leakage of gas and should be provided with a pressure relief arrangement away from operator.

Both the load break switches and the tee off circuit breaker must be motorized.

The cable box of isolators and circuit breakers both should be of front access type as per site requirement.


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Any accidental over pressure inside the sealed chamber shall be limited by the opening of a pressure-limiting device in

the top or rear-bottom part of the tank or enclosure. Gas will be release to the rear of the switchboard away from the

operator and should be directed towards the bottom, into the trench to ensure safety of the operating personnel and

the pedestrians / civilians. All the manual operations should be carried out on the front of the switchboard.

2.2 GENERAL TECHNICAL REQUIREMENTS

2.2.1 Fixed type SF-6 gas insulated / Vacuum circuit breakers. It should be maintenance free, having stainless steel

robotically/ TIG / MIG /Laser/ Manually welded enclosure for IN DOOR / OUTDOOR RMU. However, offer with high

quality of the welding which has necessary extensive leakage test with leak rate of 0.1% per annum can be accepted.

The RMUs to be used are only outdoor type.

2.2.2 Low gas pressure devices- 1.2 Bar pressure. RMU should have full rating with 0.0 Bar gas pressure.

2.2.3 Live cable indicators- High operator safety.

2.2.4 Fully Rated integral ear thing switch on each device.

2.2.5 Self powered Microprocessor Based relay- Does not require any external source of power.

2.2.6 Units fully SCADA Compatible. Retrofitting at site possible at a later date. Line switches (Load break switches) as

well as T- OFF circuit Breaker can be operated by remote. ( Manual operations should be possible in case of motor

failure.)

2.2.7 For indoor Cable boxes should be front access and interlocked with earth switch. No rear /side access required.

For outdoor RMUs cable boxes shall be on front.

2.2.8 Cable testing possible without disconnection of cables.

2.2.9 Compact in dimension.

2.2.10 Circuit Breaker with self powered O/C & E/F RELAY.

2.2.11 Low pressure, sealed for life equipment, can operate at “0” bar pressure.

2.2.12 Cable ear thing switch on all switching device-standard, for operator safety.

2.2.13 Enclosure with IP 54 standard protection for OUTDOOR RMUs and IP2X for INDOOR RMUs

2.2.14 All live parts should be inside a stainless steel enclosure for out door type RMU & minimum 2 mm thickness of

stainless steel robotically/TIG/MIG/Manually welded enclosure for Outdoor / indoor RMU. However, more / less

thickness than 2 mm of stainless steel tank as per IEC tested design may be admissible.

TECHNICAL AND GUARANTEED PARTICULARS:

The bidders shall furnish all guaranteed technical particulars as called for in Schedule “A” of this specification.

Particulars which are subject to guarantee shall be clearly marked. Bids lacking information in G.T.P are liable to be

rejected


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The Entire units or minimum three functions of RMU shall be enclosed in a single compact metal clad, outdoor

enclosure suitable for all weather conditions. The switchgear/steel gas tank shall be filled with SF6 as per IEC/IS

Standards relative pressure to ensure the insulation and breaking functions. The steel gas tank must be sealed for life

and shall meet the “sealed pressure system” criteria in accordance with the IEC 298 standard. The RMU must be a

system for which no handling of gas is required throughout the 20 years of service life.

The RMU shall have a design such that in the event of an internal arc fault, the operator shall be safe. This should be in

accordance with IEC 298 and relevant Test certificates shall be submitted with the Tender.

The offered switchgear and control gear should be suitable for continuous operation under the basic service

conditions indicated below. Installation should be in normal indoor conditions in accordance with IEC 60694.

Ambient temperature - 10 degree C to +45 degree C

Relative humidity - up to 95%

Altitude of installation - up to 1000m, IEC 60120

1.3.1 The RMU shall be tested for an internal arc rating of 16 kA for 1 Sec. for 22 KV RMU. Suitable temperature rise

test on the RMU shall be carried out & test reports shall be submitted with tender for technical bid evaluation.

Each switchboard shall be identified by an appropriately sized label, which clearly indicates the functional units and

their electrical characteristics.

The switchgear and switchboard shall be designed so that the position of the different devices is visible to the

operator on the front of the switchboard and operations are visible as well.

The entire system shall be totally encapsulated. There shall be no access to exposed conductors. In accordance with

the standards in effect, the switchboards shall be designed so as to prevent access to all live parts during operation

without the use of tools.

The entire 22 KV RMU are insulated by inert gas (SF6) suitable for operating voltage up to 24 KV respectively. The 22

KV circuit breakers must be VCB breaker. It is necessary to fit an absorption material in the tank to absorb the

moisture from the SF6 gas. The SF6 insulating medium shall be constantly monitored via a temperature compensating

gas pressure indicator offering a indication at different temperature ranges, having distinctive RED and GREEN zones

for safe operation.

All the RMUs must be routine tested for the following at factory in India:-

� Micro-ohm test for the assembly inside the tank.

� Circuit breaker analyzer test so as to ensure the simultaneous closing of all poles for VCB.

� SF6 gas leak test.

� Partial Discharge test on the complete gas tank so as to be assure of the proper insulation level and high

product life.


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� High voltages withstand.

� Secondary test to ensure the proper functioning of the live line indicators, fault passage indicators and relays.

1.3.2Sulphur Hex fluoride Gas(SF6 GAS)

The SF6 gas shall comply with IEC 376,376A, and 376B and shall be suitable in all respects for use in 22 KV RMUs under

the operating conditions. The SF6 shall be tested for purity, dew point air hydrolysable fluorides and water content as

per IEC 376,376A and 376B and test certificate shall be furnished to the owner indicating all the tests as per IEC 376

for each Lot of SF6 Gas.

DIELECTRIC MEDIUM

SF6 / VCB GAS shall be used for the dielectric medium for 22 KV RMUS in accordance with IEC376. It is preferable to fit

an absorption material in the tank to absorb the moisture from the SF6 / VCB gas and to regenerate the SF6 / VCB gas

following arc interruption. The SF6 / VCB insulating medium shall be constantly monitored via a temperature

compensating gas pressure indicator offering a simple go, no-go indication.

General structural and mechanical construction:

The offered RMU should be of the fully arc proof metal enclosed, free standing, floor mounting, flush fronted type,

consisting of modules assembled into one or more units. Each unit is made of a cubicle sealed-for life with SF6 / VCB

and contains all high voltage components sealed off from the environment.

The overall design of the indoor switchgear should be such that front access only is required. It should be possible to

erect the switchboard against a substation wall, with HV and LV cables being terminated and accessible from the front.

The units should be constructed from Minimum 2 mm thick stainless steel sheets. However, Offer with type test

report of pressure withstand test for gas filled compartment with pressure relief device test as per cl. no. 6-103-1 of

IEC 62271-200-2003 can be accepted for 2mm stainless steel tank thickness. The thickness of stainless steel tank more

/ less than 2 mm may be admissible with relevant IEC tests. The design of the units should be such that no permanent

or harmful distortion occurs either when being lifted by eyebolts or when moved into position by rollers.

For outdoor RMUs a weather proofing process shall be carried out. SHEET METAL MUST BE GRIT BLASED /

THERMALLY SPRAYED AND POLYURETHANE PAINTED WITH ABOUT 70 MICRON THICKNESSES, TO ACHIVE

OUTDOOR WORTHINESS AND CORROSION PROOF NESS.

- RMU ENCLOSURE MUST BE SHIELDED AGAINST SOLAR IRRADIATION AND TESTED FOR A

AMBIENT OF 45 DEGREE C WITHOUT DERATING OF THE EQUIPMENT.

The cubicle should be have a pressure relief device. In the rare case of an internal arc, the high pressure caused by the

arc will release it, and the hot gases is allowed to be exhausted out at the bottom / top / rear of the cubicle. A

controlled direction of flow of the hot gas should be achieved.

The switchgear should have the minimum degree of protection (in accordance with IEC 60529)


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- IP 67 for the tank with high voltage components

- IP 2X for the front covers of the mechanism

- IP 3X for the cable connection covers

- IP 54 for the outdoor enclosure.

1.4 STANDARDS:

Unless otherwise specified elsewhere in this Specification, the RMU, Switchboard (Switchgear), Load break isolators,

Instrument Transformers and other associated accessories shall conform to the latest revisions and amendments

thereof to the following standards.

1. IEC 60 298/IEC 62 271-200/IS 12729:1988 - General requirement for Metal Enclosed Switchgear

2. IEC60129/IEC62271-102/IS 9921 - Alternating current disconnector’s (Load break isolators) and earthing switch

3. IEC 62 271-100 & 200/IEC 60 056/IS 13118:1991 - Specification for alternating current circuit breaker

4. IEC 62 271-1/IEC 60694 - Panel design, SF6/Vacuum Circuit Breakers

5. IEC 60044-1/IEC 60185/IS 2705:1992 - Current Transformer

6. IEC 60265/IS 9920:1981- High voltage switches.

7. IEC 376 - Filling of SF6 gas in RMU.

8. IEC 60273/IS: 2099 - Dimension of Indoor & Outdoor post insulators i. with voltage > 1000 Volts.

9. IEC 60529/IS 13947(Part-1) - Degree of protection provided by

i. enclosures for low voltage switchgear and

ii. Control gear.

10. Indian Electricity Rules/IS Code

Equipment meeting with the requirements of any other authoritative standards, which ensures equal or better quality

than the standard mentioned above shall also be acceptable. If the equipments, offered by the Bidder conform to

other standards, salient points of difference between the standards adopted and the specific standards shall be clearly

brought out in relevant schedule. In case of any difference between provisions of these standards and provisions of

this specification, the provisions contained in this specification shall prevail. One copy of such standards with authentic

English Translations shall be furnished along with the offer.(Hard copy)

Applicable Standards

� The RMUs shall be manufactured to the highest quality consistent with best practice and workmanship

and in full accord with the Supplier’s quality assurance plan. The RMUs shall conform to the Indian or IEC

international standards that are applicable. These include the standards listed in Table 1Error! No text of

specified style in document.-1 below.

Table 1Error! No text of specified style in document.-2: Applicable Standards

Standard Description

IS 3427 AC metal enclosed switchgear and control gear for rated voltages above 1 kV and up

to and including 52 kV


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IS 12063 Classification of degrees of protection provided by enclosures of electrical

equipment

IS 9920

(Parts 1 to 4) High Voltage Switches

IS 9921

(Parts 1 to 5) Specification for AC disconnectors and earthing switches for voltages above 1000 V

IS 13118 HV AC Circuit Breakers

IS 10601 Dimensions of terminals of HV Switchgear and Control gear

IS 12729 General requirements of switchgear and control gear for voltages exceeding 1000 V

IEC 1330 High voltage/Low voltage prefabricated substations

IEC 60694 Common clauses for MV switchgear standards

IEC 6081 Monitoring and control

IS 2705 Current Transformers

IS 3156 Voltage transformers

IS 8686 Specification for Static Protective Relays

IEC 62271-

200 Standards for high voltage metal clad switchgear up to 52 KV.

INDIAN

ELECTRCIATY

REGULATION

2011

This is to be as per Central Electricity Authority (Safety Requirement for

Construction, Operation & Maintenance of Electrical Plants and Electric Lines)

Regulations, 2011

1.5 THE STANDARDS MENTIONED ABOVE ARE AVAILABLE FROM:

IEC - (INTERNATIONAL ELECTRO-TECHNICAL COMMISSION, BUREAU CENTRAL DE LA COMMISSION, ELECTRO

TECHNIQUE INTERNATIONAL, 1, RUE DE VEREMBE, GENEVA, SWITZERLAND.)

ISO - INTERNATIONAL STANDARD ORGANISATION

1.6 SPECIFIC REQUIREMENTS IN RMU:-

1.6.1 CLIMATE CONDITIONS

The climatic conditions under which the equipment should operate satisfactory are as under:

� Maximum ambient air temperature :40-45 deg. C

� Minimum ambient air temperature :10 deg.C

� Maximum daily average ambient air temperature :40 C


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� Maximum humidity :100%

� Altitude above M.S.L. (maximum) :1000 metres

� Average annual rainfall(mm) :925

� Max. wind pressure(Kg/sq.m) :200

� Seismic level(Horizontal accn.) :0.3 g

� Iso-ceraunic level(Days per Year) :50

� Average thunder storm days per annum :50

Distribution Network Electrical Parameters

The main parameters of the distribution network are as follows:

� Nominal system voltage: 22 kV (rms)

� Highest system voltage: 24 kV (rms)

� Number of phases: 3

� Frequency: 50 Hz

� Variation in frequency: 49.5 Hz to 50.5 Hz

� Type of earthing: Solid

� Power frequency withstand voltage: 50 kV

� Basic impulse withstand voltage : 125 kV

1.7 RMU OUTDOOR METAL CLAD ENCLOSURE.

The RMU enclosure must be a metallic, it shall follows an industrialized process of manufacturing. The RMU and

combination shall be tropicalised and outdoor metal enclosed type. The RMU metal parts shall be of high thickness,

high tensile steel which must be grit/short blasted, thermally sprayed with Zinc alloy, phosphate or should follow the 7

tank pre-treatment process and be subsequently painted with polyurethane based powder paint. The overall paint

layer thickness shall be not less than 80 microns.

The rating of enclosure shall be suitable for operation on three phase, three wire, 11 KV, 50 cycles, A.C. System with

short-time current rating of 16 KA for 3 seconds for 22 KV with RMU Panels.

The enclosure should have two access doors one for the operation and relay monitoring and other for the cable

access. Both the doors should have the locking facility to prevent the access to operating mechanism to avoid

unauthorized operating of RMU and relay.

1 RMU Design Features


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All design features of the proposed RMU, as described in the supplier’s bid and in the bid’s reference materials, shall

be fully supported by the equipment actually delivered. The key design features include those that relate to:

� Maintainability, expandability, and life span

� Ability to operate in severe outdoor environmental conditions.

� Immunity to electrical stress and disturbance.

� Acceptable insulation properties.

� Convenient FRTU interconnection features.

INDOOR RMU

1. MODULAR DESIGN, PANEL TYPE WITH FRONT CABLE ACCESS.

2. RMU MUST BE MADE OF ROBOTICALLY / TIG / MIG /LASER/ MANUALLY WELDED STAINLESS STEEL.


OUT DOOR RMU

6. Stainless steel enclosure for OUT DOOR RMU application. The manufacturers shall conform the normal

current ratings mentioned in GTP at 45 deg. Ambient without derating or as per IEC Standard

7. Enclosure with I.P.54 standard protection.


9. Cable boxes shall be on Front side.

10. RMU ENCLOSURE MUST BE SHIELDED AGAINST SOLAR IRRADIATION AND TESTED FOR AMBIENT OF 45

DEGREE C. The manufacturers shall conform the normal current ratings mentioned in GTP at 45 deg. Ambient

without derating, however, design for higher ambient temperature than 45 degree may be admissible.

1.8 TAKE OFF TERMINAL UNITS FOR AUTOMATION:

The RMU should be provided with necessary take off terminal units for automations, located in the front recesses / LV

cubical of the RMU. The connectivity to the FRTU for SCADA purpose shall be provided.

1.9 ISOLATORS (LOAD BREAK TYPE)

The load break isolators for Incoming and Outgoing supply must be provided. These should be fully insulated by SF6

gas. The load break isolators shall consist of 630 Amp fault making/load breaking spring assisted ring switches, each

with integral fault making earth switches. The switch shall be naturally interlocked to prevent the main and earth

switch being switched “ON‟ at the same time. The selection of the main and earth switch is made by a lever on the

facia, which is allowed to move only if the main or earth switch is in the off position. The load break isolators should

have the facility for remote operation. Each load break switch shall be of the triple pole, simultaneously operated,

automatic type with quick break contacts and with integral earthing arrangement.

The isolating distance between the OFF and the ON position in the isolator should be sufficient to withstand dielectric

test as per IS/IEC, so as to have enough isolating distance for ensuring safety during DC injection for Cable testing.

Load break switch should have the following

� Motor operated 24 KV, 630A Load Break switch and manually operated Earthing Switch with making capacity.

� “Live Cable” LED Indicators thru Capacitor Voltage Dividers mounted on the bushings.


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� Mechanical ON/OFF/EARTH Indication

� Anti-reflex operating handle

� Cable Testing facility without disconnecting the cable terminations, cable joints and terminal protectors on the

bushings.

Cable terminations

� Cable boxes suitable for 1 X 3C x 300 sq mm XLPE Cable with right angle Cable Termination Protectors.

1.10 EARTHING OF ISOLATORS AND BREAKERS (EARTH SWITCH)

Necessary arrangements are provided at Load break isolators Breaker for selecting Earth position. Mechanical

interlocking systems shall prevent the RMU function from being operated from the “ON” to “Earth On” position

without going through the “OFF” position.

1.11 DISTRIBUTION TRANSFORMER/FEEDER BREAKER (VACUUM)

The VCB breaker for the controlling of DT/Feeder Breaker must be provided inside welded stainless steel SF6

gas tank with the outdoor metal clad enclosure. The VCB circuit breaker must be a spring assisted three positions with

integral fault making earth switch. The selection of the main/earth switch lever on the facia, which is allowed to move

only if the main or earth switches is in the off position.

The manual operation of the circuit breaker shall not have an effect on the trip spring. This should only be discharged

under a fault (electrical) trip; the following manual reset operation should recharge the trip spring and reset the circuit

breaker mechanism in the main off position.

The circuit breaker shall be fitted with a mechanical flag, which shall operate in the event of a fault (electrical) trip

occurring. The “tripped” flag should be an unambiguous colour differing from any other flag or mimic.

Both the circuit breaker and ring switches are operated by the same unidirectional handle.

The protection on the circuit breaker shall comprise of the following components:-

- 3 class X protection CT‟s,

- a low burden trip coil and

- a self powered (No external DC or AC source required) IDMT

protection relays (Numeric/Micro processor based) 3 x over current and earth fault element shall be Definite Time

type relay . The protection system should be suitable for protecting transformers of rated power from 250 KVA on

wards. The relay should be housed within a pilot cable box accessible.

Circuit Breaker should have the following:

- Motor operated 200 A - 400 A – 600 A / 630A SF6 insulated Vacuum circuit breaker and Ear thing Switch with

making capacity.

- Mechanical tripped on fault indicator

- Auxiliary contacts 4NO and 4NC

- Anti-reflex operating handle


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- “Live Cable” LED Indicators thru Capacitor Voltage Dividers mounted on the bushings.

- O/C + E/F self powered relay

- Shunt Trip circuit for external trip signal

- Mechanical ON/OFF/EARTH Indication

- Cable boxes suitable for 1 X 3C x 300 sq mm XLPE Cable with right angle Cable Termination / protectors / boots.

4.0 TECHNICAL DATA

4.1 Ring Main Unit, Electrical data

Electrical data and service conditions

Rated voltage KV 24/26 KV

1 Power frequency withstand voltage KV 50

2 Impulse withstand voltage KV 125

3 Rated frequency Hz 50

4 Rated current busbars A 630

5 Rated current (cable switch) A 630

6 Rated current (T-off) A 200-400-600/ 630

Breaking capacities:

7 active load A 630

8 closed loop (cable switch) A 630

9 off load cable charging (cable switch) A 135

10 earth fault (cable switch) A 200

11 earth fault cable charging (cable switch) 115

12 short circuit breaking current (T-off circuit

breaker)

kA 20 / 21

13 Rated making capacity kA 50/52.5

14 Rated short time current 3 sec. kA 16

Ambient temperature:

15 Maximum value °C + 45

16 Maximum value of 24 hour mean °C + 40


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17 Minimum value °C 10

18 Altitude for erection above sea level4 m ...1000

19 Relative humidity Max 95%

4.2 Ring Main Unit Technical data (22KV)

No. General data, enclosure and dimensions

1 Standard to which Switchgear complies IEC

2 Type of Ring Main Unit Metal Enclosed, Panel type, Compact

Module.

3 Number of phases 3

4 Whether RMU is type tested Yes

5 Whether facility is provided with pressure relief Yes

6 Insulating gas SF6

7 Nominal operating gas pressure

1.4 bar @ 20° C. However offer with

Nominal operating gas pressure shall be as

per manufacturer standard and suitable to

satisfy the rated dielectric strength can be

accepted

8 Gas leakage rate / annum 0.075%

9 Expected operating lifetime 30 years

10 Whether facilities are provided for gas monitoring Yes, temperature compensated manometer

can be delivered

11 Material used in tank construction

Stainless steel sheet, minimum 2 mm ( Less

/ More than 2 mm thickness may be

admissible subject to IEC testing)

No. Operations, degree of protection and colours

1 Means of switch operation separate handle

2 Means circuit breaker operation separate handle and push buttons

3 Rated operating sequence of Circuit Breaker O - 3min-CO-3min-CO

4 Total opening time of Circuit Breaker approx. 45ms

5 Closing time of Circuit Breaker approx. 40ms

6 Mechanical operations of switch (co) 1000

7 Mechanical operations of CO earthing switch 1000

8 Mechanical operations of circuit breaker (co) 2000

9 Principle switch / earth switch 3 position combined switch / earth switch

Degree of protection:

10 High Voltage live parts, SF6 / VCB tank IP 67


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11 Front cover mechanism IP 2X

12 Cable covers IP 3X

13 Outdoor Enclosure IP 54

Colours:

14 Front cover

15 Side and cable cover

1.12 BUSHINGS

The units are fitted with the standardized bushings that comply with IEC standards. All the bushings are the same

height from the ground and are protected by a cable cover.

1.13 CABLE BOXES

All the cable boxes shall be air insulated suitable for dry type cable terminations and should have front access. The

cable boxes at each of the two ring switches should be suitable for accepting HV cables of sizes 3c x 300 sq.mm and

circuit breaker cable suitable up to 3c x 300 sq.mm. The cable boxes

for an isolator in its standard design should have sufficient space for connecting two cables per phase of 3c x 150

sq.mm. Necessary Right angle Boot should be supplied to the cable terminations .The type of the Right angle Boot

should be cold applied insulating Boot.

1.14 CABLE TESTING FACILITY

It shall be possible to test the cable after opening the cable boxes. The cable boxes should open only after operation of

the earth switch. Thus ensuring the earthing of the cables prior to performing the cable testing with DC injection.

1.15 VOLTAGE INDICATOR LAMPS AND PHASE COMPARATORS

The RMU shall be equipped with a voltage indication to indicate whether or not there is voltage on the cable. There

should be a facility to check the synchronization of phases with the use of external device. It shall be possible for the

each of the function of the RMU to be equipped with a permanent voltage indication as per IEC 601958 to indicate

whether or not there is voltage on the cables.

1.16 EXTENSIBLE

Each combination of RMU shall have the provision for extension by load break isolators / breakers in future, with

suitable accessories and necessary Bus Bar. The equipment shall be well designed to provide any kind of extension /

trunking chamber for connecting and housing extensible Busbars. Extensible isolators and circuit breakers shall be

individually housed in separate SF6 gas enclosures. Multiple devices inside single gas tank / enclosure will not be

acceptable. In case of extensible circuit breakers, the Breaker should be capable of necessary short circuit operations

as per IEC at 16 KA, and the Breaker should have a rated current carrying

capacity of 200 A-400A-600/630 A.

1.17 WIRING & TERMINALS:

The wiring should be of high standard and should be able to withstand the tropical weather conditions. All the wiring

and terminals (including take off terminals for future automation, DC, Control wiring), Spare terminals shall be

provided by the contractor. The wiring cable must be standard single-core non-sheathed, Core marking (ferrules),


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stripped with non-notching tools and fitted with end sleeves, marked in accordance with the circuit diagram with

printed adhesive marking strips.

The wiring should be of high standard and should be able to withstand the tropical weather conditions. All wiring shall

be provided with single core multi-strand copper conductor wires with P.V.C insulation.

The wiring shall be carried out using multi-strand copper conductor super flexible PVC insulated wires of 650/1100V

Grade for AC Power, DC Control and CT circuits. Suitable colored wires shall be used for phase identification and

interlocking type ferrules shall be provided at both ends of the wires for wire identification. Terminal should be

suitably protected to eliminate sulphating. Connections and terminal should be able to withstand vibrations. The

terminal blocks should be stud type for controls and disconnecting link type terminals for CT leads with suitable spring

washer and lock nuts.

Flexible wires shall be used for wiring of devices on moving parts such as swinging Panels (Switch Gear) or panel doors.

Panel wiring shall be securely supported, neatly arranged readily accessible and connected to equipment terminals,

terminal blocks and wiring gutters. The cables shall be uniformly bunched and tied by means of PVC belts and carried

in a PVC carrying trough.

The position of PVC carrying trough and wires should not give any hindrance for fixing or removing relay casing,

switches etc., Wire termination shall be made with solder less crimping type of tinned copper lugs. Core identification

plastic ferrules marked to correspond with panel wiring diagram shall be fitted with both ends of each wire. Ferrules

shall fit tightly on the wire when disconnected. The wire number shown on the wiring shall be in accordance with the

IS.375.

All wires directly connected to trip circuits of breaker or devices shall be distinguished by addition of a red color

unlettered ferrule.

Inter-connections to adjacent Panels (Switch Gear) shall be brought out to a separate set of Terminal blocks located

near the slots or holes to be provided at the top portion of the panel. Arrangements shall be made for easy

connections to adjacent Panels (Switch Gear) at site and wires for this purpose shall be provided and bunched inside

the panel. The bus wire shall run at the top of the panel.

Terminal block with isolating links should be provided for bus wire. Ateast 10% of total terminals shall be provided as

spare for further connections. Wiring shall be done for all the contacts available in the relay and other equipment and

brought out to the terminal blocks for spare contacts. Color code for wiring is preferable in the following colours.

� Voltage supply : Red, Yellow, Blue for phase and Black for Neutral

� CT circuits : similar to the above

� DC circuits : Grey for both positive and negative

� 250V AC circuits : Black for both phase and neutral

� Earthing : Green

The wiring shall be in accordance to the wiring diagram for proper functioning of the connected equipment. Terminal

blocks shall not be less than 650V grade and shall be piece-molded type with insulation barriers.

The terminal shall hold the wires in the tight position by bolts and nuts with lock washers. The terminal blocks shall be

arranged in vertical formation at an inclined angle with sufficient space between terminal blocks for easy wiring.


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The terminals are to be marked with the terminal number in accordance with the circuit diagram and terminal

diagram. The terminals should not have any function designation and are of the tension spring and plug-in type.

Clear empty Space shall be mandatorily provided in RMU Panel for mounting FRTU Panel. Dimensions details of

required space for FRTU are about 1000 mm H x 600 mm W x 300 mm D. 230V AC Supply for charging of FRTU battery

should be available. The Aux supply will be taken through the PT provided for metering in RMU. We require 230V AC

and not 110V AC. FRTU will require power up to 110 VA depending upon RMU configuration. The PT must have

sufficient burden for meeting the aforesaid requirement also for battery charging.

1.18 EARTHING

The RMU outdoor metal clad, Switch Gear, Load break isolators, Vacuum circuit breakers shall be equipped with an

earth bus securely fixed along the base of the RMU.

The size of the earth bus shall be made of IEC/IS standards with tinned copper flat for RMU and M.S.Flat for

Distribution Transformer, earth spike and neutral earthing. Necessary terminal clamps and connectors shall be

included in the scope of supply.

All metal parts of the switchgear which do not belong to main circuit and which can collect electric charges causing

dangerous effect shall be connected to the earthing conductor made of copper having CS area of minimum 75 mm.

Each end of conductor shall be terminated by M 12/equivalent quality and type of terminal for connection to earth

system installation. Earth conductor location shall not obstruct access to cable terminations.

The following items are to be connected to the main earth conductor by rigid or copper conductors having a minimum

cross section of 75 mm (a) earthing switches (b) Cable sheath or screen (c) capacitors used in voltage control devices,

if any.

The metallic cases of the relays, instruments and other panel mounted Equipment‟s shall be connected to the earth

bus by independent copper wires of size shall be made of IEC/IS standards. The colour code of earthing wire shall be

green. Earthing wires shall be connected on the terminals with suitable clamp connectors and soldering shall not be

permitted.

1.19 ACCESSORIES & SPARES:

The following spares and accessories shall be supplied along with the main equipments at free of costs. This shall not

be included in the price schedule.

1. Charging lever for operating load break isolators & circuit breaker of each RMU.

2. The pressure gauges indications - 1 numbers

Provision shall be made for padlocking the load break switches/ Circuit breaker, and the earthing switches in either

open or closed position with lock & master key.

1.20 TESTING OF EQUIPMENT & ACCESSORIES:

Provision for testing CTs,PTs, Relays, Breakers and Cables shall be made available. Procedure and schedule for

Periodical & Annual testings of equipments, relays, etc. shall be provided by the supplier.

1.20.1 TYPE TEST


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The Tenderers should, along with the tender documents, submit copies of all Type test certificate of their make in full

shape as confirming to relevant ISS/IEC of latest issue obtained from a International/National Govt. Lab/Recognized

laboratory.

The above type test certificates should accompany the drawings for the materials duly signed by the institution who

has type test certificate. The details of type test certificate as per Schedule F.

1.20.2 ACCEPTANCE AND ROUTINE TESTS

All acceptance and routine tests as stipulated in the latest IEC- shall be carried out by the supplier in the presence of

DISCOM’s representative. The supplier shall give at least 7 days advance intimation to the Board to enable them to

depute their representative for witnessing the tests. The partial discharge shall be carried out as routine test on each

and every completely assembled RMU gas tank and not on a sample basis. As this test checks and guarantees for the

high insulation level and thus the complete life of switchgear.

1.20.3 ADDITIONAL TESTS

The Board reserves the right for carrying out any other tests of a reasonable nature at the works of the

supplier/laboratory or at any other recognized laboratory/research institute in addition to the above mentioned type,

acceptance and routine tests at the cost of the Board to satisfy that the material complies with the intent of this

specification.

1.20.4 PRE-COMMISSIONING TESTS

All the pre-commissioning tests will be carried out in the presence of the Board testing engineer and necessary

drawing manual and periodical test tools shall be arranged to be supplied.

During the above tests the contractor representative should be present till the RMUs are put in to service.

1.21 INSPECTION:

The inspection may be carried out by the DISCOM at any stage of manufacture. The supplier shall grant free access to

DISCOM’s representative at a reasonable time when the work is in progress. Inspection and acceptance of any

equipment under this specification by the DISCOM shall not relieve the supplier of his obligation of furnishing

equipment in accordance with the specification and shall not prevent subsequent rejection if the equipment is found

to be defective.

The supplier shall keep the DISCOM informed in advance, about the manufacturing programme so that arrangement

can be made for inspection. The DISCOM reserves the right to insist for witnessing the acceptance/routine testing of

the bought out items. The DISCOM has rights to inspect the supplier’s premises for each and every consignment for

type & routine test.

No material shall be dispatched from its point of manufacture unless the material has been satisfactorily inspected

and tested / unless the same is waived by the DISCOM in writing.

1.21.1 QUALITY ASSURANCE PLAN:

The bidder shall invariably furnish following information along with his offer / in case of event of order.

I. Statement giving list of important raw materials including but not limited to

a) Contact material


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b) Insulation

c) Sealing material

d) Contactor, limit switches, etc. in control cabinet.

Name of sub-suppliers for the raw materials, list of standards according to which the raw materials are tested, list of

test normally carried out on raw materials in presence of Bidder’s representative, copies of test certificates.

II. Information and copies of test certificates as in (I) above in respect of bought out accessories & raw materials.

III. List of areas in manufacturing process, where stage inspections are to be carried out.

IV. Normally carried out for quality control and details of such tests and inspections.

V. Special features provided in the equipment to make it maintenance free.

VI. List of testing equipment available with the Bidder for final testing of RMUs and associated combinations vis-à-vis

the type, special, acceptance and routine tests specified in the relevant standards. These limitations shall be very

clearly brought out in the relevant schedule i.e. schedule of deviations from specified test requirements. The supplier

shall, within 15days from the date of receipt of Purchase Order submit following information to the DISCOM.

a) List of raw materials as well bought out accessories and the names of sub-suppliers selected from those furnished

along with offer.

b) Necessary test certificates of the raw material and bought out accessories.

c) Quality Assurance Plan (QAP) with hold points for DISCOM’s inspection. The quality assurance plan and hold points

shall be discussed between the DISCOM and supplier before the QAP is finalized.

The supplier shall submit the routine test certificates of bought out items and raw material, at the time of routine

testing of the fully assembled breaker.

1.22 TRAINING:

The supplier shall give rigorous training to the engineers & staff for 2 days in attending trouble shooting and

maintenance.

1.23 SCADA CONNECTIVITY:

Provision shall be made in all the RMUs with necessary take off terminal units for automations and connectivity with

FRTU. The all RMUs shall be motorized type and compatible for SCADA operation. All the I/O signals need to be

brought to the Terminal Strip on a Din Rail, also the Din Rail should have space to mount the MFT’s provided by SIA.

All the DI’s should be provided as potential free contacts. The CT/PT should provide metering grade core for

connecting MFT provided with FRTU. Refer Annexure-1.

The RMU should be provided with provision of following minimum signals available at separate SCADA terminal box.

Minimum signals for SCADA/DMS - to be wired

to Separate TBs

CB close / open potential free contacts


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LBS close / open potential free contacts

LBS & CB Earth Switch close /open potential free contacts

CB Test/Service Position potential free contacts

Spring charge Status indication potential free contacts

SF6 gas pressure low potential free contacts

O/C Operated potential free contacts

E/F Operated potential free contacts

Local/Remote potential free contacts

Common Power Supply Healthy potential free contacts

Motor MCB Healthy Status potential free contacts

Battery charger Fail potential free contacts

RMU Door Open potential free contacts

CB Trip Coil Healthy potential free contacts

CT & PT For SCADA Metering

FPI Control FPI remote resetting for SCADA

CB control Control from SCADA

LBS Control Control from SCADA

1.24 DOCUMENTATION and DRAWINGS

All drawings shall conform to relevant International Standards Organization (ISO) Specification. All drawings shall be in

ink and suitable for microfilming.

The tenderer shall submit along with his tender dimensional general arrangement drawings of the equipments,

illustrative and descriptive literature in triplicate for various items in the RMUs which are all essentially required for

future automation.

I. Schematic diagram of the RMU panel

II. Instruction manuals

III. Catalogues of spares recommended with drawing to indicate each items of spares

IV. List of spares and special tools recommended by the supplier.

V. Copies of Type Test Certificates as per latest IS/IEC.


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VI. Drawings of equipments, relays, control wiring circuit, etc.

VII. Foundation drawings of RMU and D.T.Structure.

VIII. Dimensional drawings of each material used for item VII.

IX. Actual single line diagram of RMU/RMUs with or without Extra combinations shall be made displayed on the

front portion of the RMU so as to carry out the operations easily.

The following should be supplied to each consignee circle/town along with the initial supply of the equipments

ordered.

a. Copies of printed and bound volumes of operation, maintenance and erection manuals in English along with

the copies of approved drawings and type test reports etc.

b. Sets of the manuals as above shall be supplied to the Chief Engineer/Distribution. A soft copy of the all

Technical and Drawing furnished in a CD

1.25 NAME PLATE:

Each RMU and its associated equipments shall be provided with a nameplate legible and indelibly marked with at least

the following information.

a. Name of manufacturer

b. Type, design and serial number

c. Rated voltage and current

d. Rated frequency

e. Rated symmetrical breaking capacity

f. Rated making capacity

g. Rated short time current and its duration

h. Purchase Order number and date

i. Month and Year of supply

j. Rated lighting impulse withstand voltage

k. Feeder name (Incoming and Outgoing), DTs Structure name, 11000 Volts Dangers etc.

NOTE:

III) THE WORD RATED NEED NOT APPEAR ON THE NAME PLATE. RECOGNIZED ABBREVIATIONS MAY BE USED TO

EXPRESS THE ABOVE PARTICULARS.


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IV) WHETHER THE CIRCUIT BREAKER IS FITTED WITH CLOSING/TRIPPING DEVICES NECESSITATING AN AUXILIARY

SUPPLY SHALL BE STATED EITHER ON THE CIRCUIT BREAKER NAME PLATE OR ANY OTHER ACCEPTABLE

POSITION.

1.26 FAULT PASSAGE INDICATORS (FPI):

These shall facilitate quick detection of faulty section of line. The fault

indication may be on the basis of monitoring fault current flow through the device.

The unit should be self-contained requiring no auxiliary power supply. The FPI shall

be integral part of RMU. The FPI shall have LCD/LED display, automatic reset

facility. FPI Reset from SCADA will be through momentary closure of a potential free contact from FRTU.

The sensors to be bushing mounted. The number of FPI should be put in all the three phases of the outgoing branch of

the RMUs

FPI should have suitable connectivity with the FRTUs for the SCADA purpose.

The FPI inside the RMU may be non communicable and hard wired to the TB for the signals. Refer Annexure-1

Fault Passage indicator OK

Fault Passage indicator operated

1.27 TROPICALISATION

Due regard should be given to the climatic conditions under which the equipment is to work. Ambient temperatures

normally vary between 20 deg C and 40 deg C, although direct sun temperature may reach 45 deg C. The climate is

humid and rapid variations occur, relative humidity between 60% and 95% being frequently recorded, but these values

generally correspond to the lower ambient temperatures. The equipment should also be designed to prevent ingress

of vermin, accidental contact with live parts and to minimize the ingress of dust and dirt. The use of materials which

may be liable to attack by termites and other insects should be avoided.

1.28 Motorization :

All the functions within the RMU i.e Isolators/Breakers should be fitted with motor mechanism and closing coil making

it suitable to make it on from remote.( However, manual mechanism should be possible in case of failure/ non working

of motor)

Other Accessories (required with RMU) :-

a) Shunt Trip Coil ( Coil voltage shall be indicated later on)

b) Battery & Battery Charger.

c) 4NO+4NC auxiliary contacts.


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1.29 Metering:

Multifunction Energy meter shall be provided by DISCOMS with, of accuracy class of 0.5 at incoming isolator of all

RMUs. The Metering CTs and PTs of suitable rating shall be

provided and wired in SCADA terminal TBs.. Refer Annexure-1.

1.30 TECHNICAL SPECIFICATION FOR RMU

1.30.1 11KV Bus Bar

I. Current Carrying Capacity : 630 Amps.

II. Short time rating current for 3 secs. : 16 KA for 22 kv

III. Insulation of bus bar : SF6

IV. Bus bar connections : Anti-oxide grease

1.31 PARAMETERS FOR SWITCH GEAR OF DT AND LOAD BREAK ISOLATORS

I. Type : Metal enclosed

II. No of Phases : 3

III. No. of poles : 3

IV. Rated voltage :24KV

V. Operating voltage :22 KV(+10% to -20%)

VI. Rated lightning impulse withstand voltage :125 KV

VII. Rated power frequency withstand voltage :50 KV

VIII. Insulating gas :SF6

IX. Rated filling level for insulation :As Per IEC.

Max.permissible site altitude at the above gas pressures : 1000m

(The operating pressure has to be adjusted for greater altitudes)

Isolating distance between ON and OFF position in isolator :80 mm (min).

Rated short time current :16 KA.for 22 kv


Rated peak withstand current :50/52.5 KA.

No of operations in Short circuit :15 Nos (minimum)

Operating mechanism: Circuit breaker with spring assisted anti reflex mechanism.

Rated current (Bus): :630 A


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Rated current (breaker) :200-400-600/630 A

Circuit Breaker interrupter :SF6 insulated VCB

Rated frequency : 50 Hz

Rated operating sequence :O-3min- CO

Number of mechanical/Remote operations for earthing : As per IEC

& Ring switches & Number of mechanical/ Remote operations for circuit breakers 60298

1.32 PRINCIPAL FEATURES

Sr.

No

DESCRIPTION Breaker

1 Circuit label Yes

2 Mimic diagram Yes

3 Supply voltage indication Yes

4 Current Transformer Yes

5 Self Powered based Microprocessor based IDMT

Relay (3OL)/EL

Yes

6 Anti - Reflexing Relay Yes

7 Interlock to defeat the operation of the line side

earthing when the line side isolator is ON.

Yes

8 Interlock to defeat the operation of the earthing

when the breaker is in service position and is ON.

Yes

9 Breaker ON/OFF indication Yes

10 Spring Charge indication / Spring assisted

mechanism.

Yes

11 Fault Tripping indication Yes

12 Bus bar end caps Yes

13 Whether the SF6 gas pressure gauge indicator and

filling arrangement.

Yes

14 Whether the spring assisted mechanism with

operating handle for ON/OFF.

Yes

15 Whether the earth positions with arrangement for

padlocking in each position and independent

manual operation with mechanically operated

indicator are provided

Yes

16 RMUs are provided with necessary take off

terminals for future automation.

Yes

1.33 Earthing switch for 22 KV Line side Isolation and DT

Rated short time current : 16 KA.for 22 kv.



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Rated peak withstand current :50/52.5 KA

Interlocking facility:

1) Between 22 KV Line side isolator “ON”&Earthing.

2) Between 22 KV DT side breaker on close condition & earthing

1.34 Current Transformers for breaker

CT Type : Tape wound

CT Description : The CTs of breaker shall be Suitable for sensing the minimum

primary variable current in the order of 10-200 A and the secondary current for the CT is 1 A. The CT

shall be housed in outside SF6 chamber for testing and Maintenance


Rated burden : Suitable for self powered relay and metering.


Page 49 of 95

PART A&B: TECHNICAL SPECIFICATION FOR FIXING OF END TERMINATION AND

STRAIGHT THROUGH JOINTS FOR OUTDOOR 11/22 KV RING MAIN UNIT

SWITCHGEAR

Fixing of end termination & straight through joints.

1.

(i) Contractor should clarify the make of cable end termination. The heat & shrink type end termination shall be utilized for the job.

(ii) After completing work of cable laying end termination, following test shall be carried out jointly by engineer in charge of DISCOM and contractor.

(iii) Insulation resistance test before & after with 5 KV insulation tester. (A) Hypo test (iv) Contractor has to furnish Guaranteed Technical Parameters (GTP) type test

certificate of various tests conducted at any Govt./ NABL approved laboratory for the End Termination Kit they intend to supply for this job. The test certificate should not be prior to 5 years from the date of tender. The contractor shall have to submit the same with technical bid and failure in which technical bid will be disqualified & the price bid of that party will not be opened.

(v) One competent skilled supervisor shall have to co-ordinate the site authority and he has to do all communication with engineer in charge of DISCOM.

(vi) It is essential to have suppliers certificate of training for cable jointing of cable jointer. (vii) Jointer has to ensure safety while making joints so that other nearby cables will not

damaged. (viii) The material of End termination kit will be inspected at manufacturer’s works by the

inspector of DISCOM. The bidder has to give inspection call 15 days in advance to S.E. (O&M) for the works to be carried out in their jurisdiction.

2 The Bidder shall have to supply cable end Terminal kit as per IS 13573-1992 with latest amendment No. 2, 1998 IEEE 48-1990 and shall be Class -1, ESI-09-13 performance specification for high voltage cable accessories.

3 The work of laying of cable along the road / road crossing to be carried out by Horizontal Drilling Machine / Auger boring machine enclosed in HDPE Pipe only.

CLASS OF TERMINATION:


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The XLPE 11/22 KV Link Line shall be class 1 termination as per appropriate ISI code nos.

i.e. IEEE-48-1990.

APPLICABLE STANDARDS:

IS 13573-1992 with latest amendment – Latest amendment No. 2, 1998. IEEE 48-1990. The

termination shall be Class 1. ESI-09-13 performance specification for high voltage cable

accessories. The cable accessories being supplied in the form of kit which has different

components to be assembled at site.

MATERIALS:

The term 11 KV / 22 kV XLPE Cable refers to extruded or Molded Polymeric. Polymeric

material which are cross linked by gamma radiation to develop elastic memory and supplied

in an expanded or otherwise deformed size and shape. Bidders should submit the proof

that the tubes are cross linked by gamma radiations. However chemically cross linked,

crotch seal and lug seals are permitted.

For end termination kit, the insulation over the ferrules should be reinsulated by dual wall

tubing. This should have an inner insulating layer vulcanized to an outer semi-conducting

layer. This is required to ensure reconnection of cable insulation screen of the core from one

end of the joint to the other. The dual wall tubing ensures that there is no entrapment of air

pockets between the insulating and semi-conducting layers.

FOR JOINTS:

11 kV / 22 kV XLPE underground flexible polymeric tubing, preferably black colored pre coated with adhesive

shall be provided for sealing the exposed metallic sheaths and sheath/earth connections.

PROVISION OF ADDITIONAL CREEPAGE INDOOR / OUTDOOR TERMINATIONS:

Single piece, 11/22 KV XLPE underground cable, weather sheds having non-tracking, erosion and

weather resistant properties shall be supplied with the kits for application over non-tracking tubing.

The quantity of sheds to be supplied shall depend on voltage grade and indoor/outdoor application


Page 51 of 95

and shall be indicated along with offer. Each shed shall give an additional creepage length of at least

100mm.

INSULATION AND SCREEN REINSTATEMENT FOR END TERMINAL KITS: The reinstatement of insulation shall be by means of heat shrinkable, flexible, polymeric tubing

made from a discharge resistant polymer, preferably colored red. The tubing after complete

recovery shall have a minimum wall thickness to ensure provisions of adequate insulation in step.

EARTH & SCREEN CONTINUITY FOR TERMINATION: Screen continuity by using tinned copper mesh and earth continuity by using tinned copper

braids of appropriate size shall be provided for transfer of screen/earth.

In termination, tinned copper braids of appropriate size or equivalent current carrying

capacity of cable conductor along with copper lugs of appropriate size shall be provided for

continuity of screen to armour to the earth.

LUGS & FERRULES: The requisite number and type of aluminum/ copper lugs/ferrules shall be provided for termination/joints. The Lugs

and ferrules for XLPE cables shall be crimping type suitable for compacted circular conductor having two nos. of holes.


Page 52 of 95

Guaranteed Technical Particulars Annexure a

for Heat Shrink Outdoor end termination on 11 KV (E) XLPE Cable

Sr.No Particulars Unit Guaranteed Values

1.0 APPLICABLESTANDARDS As per IS:13573

2.0 GUARANTEED PARTICULARS For the nominal (phase to phase) System Voltages Maximum system voltage

KV 11KV - 12KV

2.1 A.C. withstand voltage (ph / ground) Time duration

KV Mins 35KV1Min.

2.2 Partial Discharge at 2 Uo pC <5 pC

2.3 Impulse Withstand, 1.2 / 50 / Us kV 75KV

2.4

Load Cycle Test a) Each Cycle Heating Duration Temperature Cooling duration b)Number of Cycles c) Continuous phase to ground Voltage Withstand

Hrs ºC Hrs KV

5 100 3 63 2.5Uo

2.5 ThermalWithstandShortcircuitcurrent1Sec. Ka As per IS:13573

2.6 Dynamic short circuit withstand Ka Peak 2.55 xls as per IS:13573

2.7 DC Voltage KV 48 KV for 30 Mins.

3.0 KITPARTICULARS

3.1 Material of the tubing/ moulded party Polyolefin

3.2 Method of stress control High permittivity Material.


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3.3 Method of environmental seal H. S. Black Insulating Tubes

3.4

List of items included in the Kit a) For Terminations b) Allowable Kit storage Temperature. c) Kit self life

ºC Years Yes. Normal Ambient Temperature. More than 5 years.

4.0 Cable Termination Instruction Manuals Yes/ No Yes


Page 54 of 95

Guaranteed Technical Particulars Annexure b Heat Shrink Straight through joint on 11 KV (E) XLPEC able

Sr.No. Particulars Unit Guaranteed Values

1.0 APPLICABLESTANDARDS

AsperIS:13573

GUARANTEEDPARTICULARS

For the nominal (phase to phase)

2.0 System Voltage KV 11KV

Maximum system voltage KV 12KV

A.C. withstand voltage Dry (ph/ground) KV 35KV 2.1

Time duration Mins 1 Min.

2.2 Partial Discharge at 2 Uo pC <5pC

2.3 Impulse Withstand, 1.2/50/Us kV 75KV

Load Cycle Test

a) Each Cycle Heating Duration Hrs 5

Temperature ºC 100

2.4 Cooling Hrs. 3

b) Number of Cycles

63

c) Continuous phase to ground voltage Withstand kV 2.5 Uo

Water tightness test KV

60 Nos. at 2.5Uo as per above cycles.

2.5 ThermalWithstandShortcircuitcurrent1Sec.

ka As per IS;13573

2.6 Dynamic short circuit withstand ka Peak

2.55 xls As per IS:135373

2.7 DC Voltage kV 48 kV for 30 Mins.

3.0 KITPARTICULARS


3.2 Method of stress control

High permittivity Material.

3.3 Method of environmental seal

H.S. Black Insulating Tubes.

List of items included in the Kit Yes/No

a) For joints Yes


Page 55 of 95

3.4 b) Allowable Kit storage Temperature ºC Normal Ambient Temperature

c) Kit shelf life Years More than 5 years

4.0 Cable Termination Instruction Manuals

Yes/No Yes

Guaranteed Technical Particulars Annexure c

Heat Shrink Indoor termination on 22 kV (E) XLPE Cable




For the nominal (phase to phase) 2.0

System Voltage KV 22 KV

Maximum system voltage KV 24 KV

2.1 A.C. withstand voltage Dry (ph/ground)

KV 35 KV



2.3 Impulse Withstand, 1.2 / 50 / Us kV 125KV

Load Cycle Test

a)Each Cycle Heating Duration Hrs 5

Temperature ºC

100

2.4 Cooling duration Hrs. 3

b) Number of Cycles 126

c) Continuous phase to ground voltage Withstand kV 2.5 Uo

2.5 Thermal Withstand Short circuit current 1 Sec. ka AsperIS:13573


2.55xlsAsperIS:135373

2.7 DC Voltage kV 96kVfor30Mins.

3.0 KITPARTICULARS

3.1 Material of the tubing/ moulded party

Polyolefin


3.3 Method of environmental seal H.S. Anti tracking Tubes.

List of items included in the Kit

a) For Terminations Yes


c) Kit shelf life Years Morethan5years


Page 56 of 95


Yes/No Yes

Guaranteed Technical Particulars Annexure-d Heat Shrink straight through joint on 22 kV (E) XLPE Cable

Sr. No. Particulars Unit Guaranteed Values




System Voltage KV 22KV


2.1 A.C. withstand voltage Dry (ph/ground)

KV 55KV


2.2 PartialDischargeat2Uo pC <5pC

2.3 ImpulseWithstand,1.2/50/Us kV 125KV

Load Cycle Test


Temperature

ºC 100

Cooling duration Hrs. 3 2.4


c) Continuous phase to ground voltage Withstand

kV 2.5 Uo

Water tightness test KV

60 Nos. at 2.5 Uo as per above cycles.





3.0 KITPARTICULARS

3.1 Material of the tubing/ moulded party

Polyolefin




a) For Joints Yes



Page 57 of 95



Yes/No Yes

Guaranteed Technical Particulars Annexure -e

Heat Shrink outdoor termination on 22 kV (E) XLPE Cable





System Voltage KV 22KV


2.1

A.C. withstand voltage Dry (ph/ground) KV 55KV



2.3 ImpulseWithstand,1.2/50/Us kV 125KV

Load Cycle Test


Temperature

ºC 100

2.4 Cooling duration Hrs. 3


c) Continuous phase to ground voltage Withstand

kV 2.5 Uo

Leak Tightness 9 Cycles





3.0 KITPARTICULARS





a) For Terminations Yes




Yes/No Yes


Page 58 of 95

PART A&B :Technical specifications of cable work

1.1 SCOPE

This chapter covers the requirements for the selection, installation and jointing of

power cables for low, medium and high voltage applications upto and including 22 KV.

For details not covered in these Specifications, IS:1255-1983 shall be referred to. All

references to BIS-Specifications and codes are for codes with amendments issued upto

date i.e. till the date of call of tender.

1.2 TYPES OF CABLES

1.2.1 The cables for applications for low and medium voltage (upto and including

1.1KV) supply shall be one of the following: -

(i) PVC insulated and PVC sheathed, conforming to IS:1554 (Part-1)- 1988

(ii) Cross linked polyethylene insulated, PVC sheathed (XLPE), conforming

to IS: 7098 (Part-1)- 1988.

1.2.2 The cables for applications for high voltage (above 1.1KV but upto and including

22 KV supply) supply shall be one of the following: -

(i) PVC insulated and PVC sheathed, conforming to IS:1554 (Part-2)- 1988.

(ii) Paper insulated, lead sheathed (PILCA) conforming to IS:692-1973

(iii) Cross linked polyethylene (XLPE) insulated, PVC sheathed conforming to

IS:7098 (Part-2)- 1985.

1.2.3 The cables for applications above 11KV but upto and including 22KV supply

shall be one of the following: -

(i) Paper insulated lead sheathed (PILCA) conforming to IS: 692-1973.

(ii) Cross linked, polyethylene insulated (XLPE) conforming to IS:7098

(Part-2)-1985.

1.2.4 The cables shall be with solid or stranded aluminium conductors, as specified.

Copper conductors may be used, only in special applications, where use of aluminium

conductors is not technically acceptable.

1.2.5 Where paper insulated cables are used in predominantly vertical situation, these

shall be of non-draining type.

1.3 ARMOURING AND SERVING

1.3.1 All multicore cables liable for mechanical damage and all HV cabkes

(irrespective of the situation of installation) shall be armoured. Where armouring is

unavoidable in dingle core cables, either the armour should be made of nonmagnetic

material, or it should be ensured that the armouring is not shorted at terminations, thus

preventing the flow of circulating currents therein.


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1.3.2 Short runs of cables laid in pipes, closed masonary trenches and similar protected

or secured enclosures need not be armoured.

1.3.3 PVC and XLPE cables, when armoured, shall have galvanized steel wires (flat or

round) for armouring.

1.3.4 Paper insulated cables shall have for armouring, a double layer of steel tape for

normal applications. Steel wire armouring is preferred where the cables are liable to

tensile stresses in applications such as vertical runs, suspended on brackets or laid in soil

that is likely to subside.

1.3.5 Serving over armouring in paper insulated cables shall consist of a complete layer

or layers of suitable compounded Hessian materials.

1.4 SELECTION OF CABLE SIZES

1.4.1 The cable sizes shall be selected by considering the voltage drop in the case of

MV (distribution) cables and Current carrying capacity in the case of HV (feeder) cables.

Due consideration should be given for the Prospective short circuit current and the period

of its flow, especially in the case of HV cables.

1.4.2 While deciding upon the cable sizes, derating factors for the type of cable and

depth of laying, grouping, ambient temperature, ground temperature, and soil resistivity

shall be taken into account.

1.4.3 Guidance for the selection of cables shall be served from relevant Indian

Standards such as IS:3961 (Part-1)-1967 for paper insulated lead sheathed cables, IS:

3961 (Part-2)-1967 for PVC insulated and PVC sheathed heavy duty cables, IS: 5819-

1970 for recommended short circuit ratings of high voltage PVC cables, IS: 1255-1983

on code of practice for installation and maintenance of power cables upto and including

22 KV rating etc.

1.5 STORAGE AND HANDLING

1.5.1 Storage

(i) The cable drums shall be stored on a well drained, hard surface, so that the

drums do not sink in the ground causing rot and damage to the cable drums. Paved

surface is preferred, particularly for long term storage.

(ii) The drums shall always be stored on their flanges, and not on their flat

sides.

(iii) Both ends of the cables especially of PILCA cables should be properly

sealed to prevent ingress/ absorption of moisture by the insulation during storage.


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(iv) Protection from rain and sun is preferable for long term storage for all

types of cables. There should also ventilation between cable drums.

(v) During storage, periodical rolling of drums once in, say, 3 months through

90 degrees shall be done, in the case of paper insulated cables. Rolling shall be done in

the direction of the arrow marked on the drum.

(vi) Damaged battens of drums etc. should be replaced as may be necessary.

1.5.2 Handling

(i) When the cable drums have to be moved over short distances, they should

be rolled in the direction of the arrow marked on the drum.

(ii) For manual transportation over long distances, the drum should be

mounted on cable drum wheels, strong enough to carry the weight of the drum and pulled

by means of ropes. Alternatively, they may be mounted on a trailer or on a suitable

mechanical transport.

(iii) For loading into and unloading from vehicles, a crane or a suitable lifting

tackle should be used. Small sized cable drums can also be rolled down carefully on a

suitable ramp or rails, for unloading, provided no damage is likely to be caused to the

cable or to the drum.

1.6 INSTALLATION

1.6.1 General

(i) Cables with kinks, straightened kinks or any other apparent defects like

defective armouring etc. shall not be installed.

(ii) Cables shall not be bent sharp to a small radius either while handing or in

installation. The minimum safe bending radius for PVC/XLPE (MV) cables shall be 12

times the overall diameter of the cable. The minimum safe bending radius for

PILCA/XLPE (HV) cables shall be as given in Table-II. At joints and terminations, the

bending radius of individual cores of a multi core cable of any type shall not be less than

15 times its overall diameter.

(iii) The ends of lead sheathed cables shall be sealed with solder immediately

after cutting the cables. In case of PVC cables, suitable sealing compound/tape shall be

used for this purpose, if likely exposed to rain in transit storage. Suitable heat shrinkable

caps may also be used for the purpose.


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1.6.2 Route

Before the cable laying work is undertaken, the route of the cable shall be decided

by the Engineer-in-Charge considering the following.

(i) While the shortest practicable route should be preferred, the cable route

shall generally follow fixed developments such as roads, foot paths etc. with proper

offsets so that future maintenance, identification etc. are rendered easy. Cross country run

merely to shorten the route length shall not te adopted.

(ii) Cable route shall be planned away from drains and near the property,

especially in the case of LV/MV cables, subject to any special local requirements that

may have to be necessarily complied with.

(iii) As far as possible, the alignment of the cable route shall be decided after

taking into consideration the present and likely future requirements of other services

including cables enroute, possibility of widening of roads/lanes etc.

(iv) Corrosive soils, ground surrounding sewage effluent etc. shall be avoided

for the routes.

(v) Route of cables of different voltages.

(a) Whenever cables are laid along well demarcated or established roads, the

LV/MV cables shall be laid farther from the kerb line than HV cables.

(b) Cables of different voltages, and also power and control cables shall be

kept in different trenches with adequate separation. Where available space is restricted

such that this requirement cannot be met, LV/MV cables shall be laid above HV cables.

(c) Where cables cross one another, the cable of higher voltage shall be laid at

a lower level than the cable of lower voltage.

1.6.3 Proximity to communication cables

Power and communication cables shall as far as possible cross each other at right

angles. The horizontal and vertical clearances between them shall not be less than 60cm.

1.6.4 Railway crossing Cables under railway tracks shall be laid in spun reinforced concrete, or cast iron

or steel pipes at such depths as may be specified by the railway authorities, but not less

than 1m, measured from the bottom of the sleepers to the top of the pipe. Inside railway

station limits, pipes shall be laid upto the point of the railway station limits, pipes shall be

laid upto a minimum distance of 3m from the center of the nearest track on either side.


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1.6.5 Way Leave

Way leave for the cable route shall be obtained as necessary, from the appropriate

authorities, such as, Municipal authorities, Department of telecommunication, Gas

Works, Railways, Civil Aviation authorities, Owners of properties etc. In case of private

property, Section 12/51 of the Indian Electricity Act shall be complied with.

1.6.6 Methods of laying

The cables shall be laid direct in ground, pipe, closed or open ducts, cable trays or

on surface of wall etc. The method(s) of laying required shall be specified in the tender

schedule of work.

1.6.7 Laying direct in ground

1.6.7.1 General

This method shall be adopted where the cable route is through open ground, along

roads/lanes, etc. and where no frequent excavations are likely to be encountered and

where re-excavation is easily possible without affecting other services.

1.6.7.2 Trenching

(i) Width of trench

The width of the trench shall first be determined on the following basis

(Refer figure 1)

(a) The minimum width of the trench for laying a single cable shall be 35cm

(b) Where more than one cable is to be laid in the same trench in horizontal

formation, the width of the trench shall be increased such that the inter-axial spacing

between the cables, except where otherwise specified, shall be at least 20cm.

© There shall be a clearance of at least 15cm between axis of the end cables

and the sides of the trench.

(ii) Depth of trench

The depth of the trench shall be determined on the following basis (Refer figure 1): -

(a) Where the cables are laid in a single tier formation, the total depth of

trench shall not be less than 75cm for cables upto 1.1KV and 1.2m for cables above

1.1KV.

(b) When more than one tier of cables is unavoidable and vertical formation

of laying is adopted, the depth of the trench in (ii) a above shall be increased by 30cm for

each additional tier to be formed.


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© Where no sand cushioning and protective covering are provided for the

cables as per 2.6.7.3(i)(b), 2.6.7.3(vii)(c) and 2.6.7.3(ix)(d) below, the depth of the trench

as per (ii)(a) and (b) above shall be increased by 25cm.

(iii) Excavation of trenches

(a) The trenches shall be excavated in reasonably straight lines. Wherever

there is a change in the direction, a suitable curvature shall be adopted complying with

the requirements of clause 2.6.1(ii).

(b) Where gradients and changes in depth are unavoidable, these shall be

gradual.

© The bottom of the trench shall be level and free from stones, brick bats etc.

(d) The excavation should be done by suitable means-manual or mechanical.

The excavated soil shall be stacked firmly by the side of the trench such that it may not

fall back into the trench.

(e) Adequate precautions should be taken not to damage any existing cable(s),

pipes or any other such installations in the route during excavation. Wherever trickd, tiles

or protective covers or bare cables are encountered, further excavation shall not be

carried out without the approval of the Engineer-in-Charge.

(f) Existing property, if any, exposed during trenching shall be temporarily

supported adequately as directed by the Engineer-in-Charge. The trenching in such cases

shall be done in short lengths, necessary pipes laid for passing cables therein and the

trench refilled in accordance with clause 2.6.7.4.

(g) It there is any danger of a trench collapsing or endangering adjacent

structures, the sides may be left in place when back filing the trench.

(h)Excavation through lawns shall be done in consultation with the Department

concerned.

1.6.7.3

Laying of cable in trench

(i) Sand cushioning

(a) The trench shall then be provided with a layer of clean, dry sand cushion

of not less than 8cm in depth, before laying the cables therein.

(b) However, sand cushioning as per (a) above need not be provided for MV

cables, where there is no possibility of any mechanical damage to the cables due to heavy

or shock loading on the soil above. Such stretches shall be clearly specified in the tender

documents.

© Sand cushioning as per (a) above shall however be invariably provided in

the case of HV cables.

(ii) Testing before laying All the time of issue of cables for laying, the cables shall be tested for continuity

and insulation resistance (See also clause 2.8.1)


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(iii) The cable drum shall be properly mounted on jacks, or on a cable wheel at a

suitable location, making sure that the spindle, jack etc. are strong enough to carry the

weight of the drum without failure, and that the spindle is horizontal in the bearings so as

to prevent the drum creeping to one side while rotating.

(iv) The cable shall be pulled over on rollers in the trench steadily and uniformly

without jerks and strain. The entire cable length shall as far as possible be laid off in one

stretch. PVC/XLPE cables less than 120sq.mm. size may be removed by “Flaking” i.e. by

making one long loop in the reverse direction.

Note: - For short runs and sizes upto 50sq.mm. of MV cables, any other suitable method

of direct handing and laying can be adopted without strain or excess bending of the

cables.

(v) After the cable has been so uncoiled, it shall be lifted slightly over the rollers

beginning from one and by helpers standing about 10m apart and drawn straight. The

cable shall then be lifted off the rollers and laid in a reasonably straight line.

(vi) Testing before covering

The cables shall be tested for continuity of cores and insulation resistance (Refer clause

2.8.1) and the cable length shall be measured, before closing the trench. The cable end

shall be sealed /covered as per clause 2.6.1 (iii)

(vii) Sand covering

Cables laid in trenches in a single tier formation shall have a covering of dry sand of not

less than 17cm above the base cushion of sand before the protective cover is laid.

In the case of vertical multi-tier formation, after the first cable has been laid, a sand

cushion of 30cm shall be provided over the base cushion before the second tier is laid. If

additional tiers are formed, each of the subsequent tiers also shall have a sand cushion of

30cm as stated above. Cables in the top most tiers shall have final sand covering not less

than 17cm before the protective cover is laid.

Sand covering as per (a) and (b) above need not be provided for MV cables where a

decision is taken by the Engineer-in-Charge as per sub clause (i)(b) above, but the inter

tier spacing should be maintained as in (b) above with soft soil instead of sand between

tiers and for covering.

Sand cushioning as per (a) and (b) above shall however be invariably provided in the case

of HV cables.


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(viii) Extra loop cable

(a) At the time of original installation, approximately 3m of surplus cable shall be left

on each terminal end of the cable and on each side of the underground joints. The surplus

cable shall be left in the form of a loop. Where there are long runs of cables such loose

cable may be left at suitable intervals as specified by the Engineer-in-Charge.

(b) Where it may not be practically possible to provide separation between cables

when forming loops of a number of cables as in the case of cables emanating from a

substation, measurement shall be made only to the extent of actual volume of excavation,

sand filling etc. and paid for accordingly.

(ix) Mechanical protection over the covering

(a) Mechanical protection to cables shall be laid over the covering in accordance with

(b) and (c) below to provide warning to future excavators of the presence of the cable

and also to protect the cable against accidental mechanical damage by pick-axe blows etc.

(b) Unless otherwise specified, the cables shall be protected by second class brick of

nominal size 22cmX11.4cmX7 cm or locally available size, placed on top of the sand (or,

soil as the case may be). The bricks shall be placed breadth-wise for the full length of the

cable. Where more than one cable is to be laid in the same trench, this protective covering

shall cover all the cables and project at least 5cm over the sides of the end cables.

© Where bricks are not easily available, or are comparatively costly, there is no

objection to use locally available material such as tiles or slates or stone/cement concrete

slabs. Where such an alternative is acceptable, the same shall be clearly specified in the

tender specifications.

(d) Protective covering as per (b) and (c) above need not be provided only for MV

cables, in exceptional cases where there is normally no possibility of subsequent

excavation. Such cases shall be particularly specified in the Tender specifications.

(e) The protective covering as per (b) and (c) above shall, however invariably be

provided in the case of HV cables.

1.6.7.4 Back filling

(i) The trenches shall be then back-filled with excavated earth, free from

stones or other sharp ended debris and shall be rammed and watered, if necessary in

successive layers not exceeding 30cm depth.

(ii) Unless otherwise specified, a crown of earth not less than 50mm and not

exceeding 100mm in the center and tapering towards the sides of the trench shall be left


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to allow for subsidence. The crown of the earth however, should not exceed 10 Cms so as

not to be a hazard to vehicular traffic.

(iii) The temporary re-statements of roadways should be inspected at regular

intervals, particularly during wet weather and settlements should be made good by further

filling as may be required.

(iv) After the subsidence has ceased, trenches cut through roadways or other

paved areas shall be restored to the same density and materials as the surrounding area

and –re-paved in accordance with the relevant building specifications to the satisfaction

of the Engineer-in-Charge.

(v) Where road beams or lawns have been cut out of necessity, or kerb stones

displaced, the same shall be repaired and made good, except for turfing /asphalting, to the

satisfaction of the Engineer-in-Charge and all the surplus earth or rock shall be removed

to places as specified.

1.6.7.5 Laying of single core cables

(i) Three single core cables forming one three phase circuit shall normally be

laid in close trefoil formation and shall be bound together at intervals of approximately

1m.

(ii) The relative position of the three cables shall be changed at each joint at

the time of original installation, complete transposition being effected in every three

consecutive cable lengths.

1.6.7.6 Route markers

(i) Location

Route markers shall be provided along the runs of cables at locations approved by the

Engineer-in-Charge and generally at intervals not exceeding 100m. Markers shall also be

provided to identity change in the direction of the cable route and at locations of

underground joints.

(ii) (a) Plate type marker

Route markers shall be made out of 100mm X 5mm GI/ aluminium plate welded / bolted

on 35mm X 35mm X 6mm angle iron, 60cm long. Such plate markers shall be mounted

parallel to and at about 0.5m away from the edge of the trench.


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(b) CC marker

Alternatively, cement concrete 1:2:4 (1 cement:2 coarse sand: 4 graded stone aggregate

of 20mm in size) as shown in figure 2 shall be laid flat and centered over the cable. The

concrete markers, unless otherwise instructed by the Engineer-in-Charge, shall project

over the surrounding surface so as to make the cable route easily identifiable.

(c) Inscription

The words ‘CPWD-MV/HV CABLE’ as the case may be, shall be inscribed on the

marker.

1.6.8 Laying in pipes / closed ducts

1.6.8.1 In locations such as road crossing, entry in to buildings, paved areas etc. cables

shall be laid in pipes or closed ducts. Metallic pipe shall be used as protection pipe for

cables fixed on poles of overhead lines.

1.6.8.2

(i) Stone ware pipes, GI, CI or spun reinforced concrete pipes shall be used for

cables in general; however only GI pipe shall be used as protection pipe on poles.

(ii) The size of the pipe shall not be less than 10cm in diameter for a single cable and

not less than 15cm for more than one cable.

(iii) Where steel pipes are employed for protection of single core cable feeding AC

load, the pipe should be large enough to contain both cables in the case of single phase

system and all cables in the case of poly phase system.

(iv) Pipes for MV and HV cables shall be independent ones.

1.6.8.3

(i) In the case of new construction, pipes as required (including for anticipated future

requirements) shall be laid alongwith the civil works and jointed according to the CPWD

Building Specifications.

(ii) Pipes shall be continuous and clear of debris or concrete before cables are drawn.

Sharp edges if any, at ends shall be smoothened to prevent damage to cable sheathing.

(iii) These pipes shall be laid directly in ground without any special bed except for SW

pipe which shall be laid over 10cm thick cement concrete 1:5:10 (1 cemtnt:5coarse

sand:10 graded stone aggregate of 40mm nominal size) bed. No sand cushioning or tiles

need be used in such situations.

1.6.8.4 Road crossings

(i) The top surface of pipes shall be at a minimum depth of 1m from the pavement

level when laid under roads, pavements etc.

(ii) The pipes shall be laid preferably askew to reduce the angle of bend as the cable

enters and leaves the crossing. This is particularly important for HV cables.


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(iii) When pipes are laid cutting an existing road, care shall be taken so that the soil

filled up after laying the pipes is rammed well in layers with watering as required to

ensure proper compaction. A crown of earth not exceeding 10cm should be left at the top.

(iv) The temporary re-instatements of roadways should be inspected at regular

intervals, particularly after a rain, and any settlement should be made good by further

filling as may be required.

(v) After the subsidence has ceases, the top of the filled up trenches in roadways or

other paved areas shall be restored to the same density and material as the surrounding

area in accordance with the relevant CPWD Building Specifications to the satisfaction of

the Engineer-in-Charge.

1.6.8.5 Manholes shall be provided to facilitate feeding/drawing in of cables with

sufficient working space for the purpose. They shall be covered by suitable manhole

covers. Sizes and other details shall be indicated in the Schedule of work.

1.6.8.6 Cable entry into the building

Pipes for cable entries to the building shall slope downwards from the building. The pipes

at the building end shall be suitably sealed to avoid entry of water, after the cables are

laid.

1.6.8.7 Cable-grip / draw-wires, winches etc. may be employed for drawing cables

through pipes / closed ducts.

1.6.8.8 Measurement for drawing/ laying cables in pipes/ closed duct shall be on the basis

of the actual length of the pipe / duct for each run of the cable, irrespective of the length

of cable drawn through.

1.6.9 Laying in open ducts

1.6.9.1 Open ducts with suitable removable covers (RCC slabs or chequered plates) are

generally provided in sub-stations, switch rooms, plant rooms, workshops etc. for taking

the cables. The cable ducts should be of suitable dimensions for the number of cables

involved.

1.6.9.2

(i) Laying of cables with different voltage ratings in the same duct shall be avoided.

Where it is inescapable to take HV & MV cables same trench, they shall be laid with a

barrier between them or alternatively, one of the two (HV &MV) cables may be taken

through pipe(s).

(ii) Splices or joints of any type shall not be permitted inside the ducts.

1.6.9.3

(i) The cables shall be laid directly in the duct such that unnecessary crossing of

cables is avoided.


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(ii) Where specified, cables may be fixed with clamps on the walls of the duct or

taken in hooks/brackets/troughs in ducts.

1.6.9.4

Where specified, ducts may be filled with dry sand after the cables are laid and covered

as above, or finished with cement plaster, specially in high voltage applications.

1.6.10

Laying on surface

1.6.10.1

This method may be adopted in places like switch rooms, workshops, tunnels, rising

(distribution) mains in buildings etc. This may also be necessitated in the works of

additions and/or alterations to the existing installation, where other methods of laying

may not be feasible.

1.6.10.2

Cables may be laid in surface by any of the following methods as specified:

(a) Directly clamped by saddles or clamps,

(b) Supported on cradles,

(c) Laid on troughs/trays, duly clamped.

1.6.10.3

(i) The saddles and clamps used for fixing the cables on surface shall comply with

the requirements given in Table-III.

(ii) Saddles shall be secured with screws to suitable approved plugs. Clamps shall be

secured with nuts on to the bolts, grouted in the supporting structure in an approved

manner.

(iii) In the case of single core cables, the clamps shall be of non-magnetic material. A

suitable non-corrosive packing shall be used for clamping unarmoured cables to prevent

damage to the cable sheath.

(iv) Cables shall be fixed neatly without undue sag or kinks.

1.6.10.4

The arrangement of laying the cables in cradles is permitted only in the case of cables of

1.1KV grade of size exceeding 120sq.mm. In such cases, the cables may be suspended on

MS flat cradles of size 50mmX5mm which in turn shall be fixed on the wall by bolts

grouted into the wall in an approved manner at a spacing of not less than 60cm.

1.6.10.5

All MS components used in fixing the cables shall be either galvanized or given a coat of

red oxide primer and finished with 2 coats of approved paint.


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1.6.11 Laying on cable tray

1.6.11.1

This method may be adopted in places like indoor substations, air-conditioning plant

rooms, generator rooms etc. or where long horizontal runs of cables are required within

the building and where it is not convenient to carry the cable in open ducts. This method

is preferred where heavy sized cables or a number of cables are required to be laid. The

cable trays may be either of perforated sheet type or of ladder type.

1.6.11.2 Perforated type cable tray

(i) The cable tray shall be fabricated out of slotted/perforated MS sheets as

channel sections, single or double bended. The channel sections shall be supplied in

convenient lengths and assembled at site to the desired lengths. These may be

galvanished or painted as specified. Alternatively, where specified, the cable tray may be

fabricated by two angle irons of 50mmX50mmX6mm as two longitudinal members, with

cross bracings between them by 50mmX5mm flats welded/bolted to the angles at 1 m

spacing. 2mm thick MS perforated sheet shall be suitably welded/bolted to the base as

well as on the two sides.

(ii) Typically, the dimensions, fabrication details etc. are shown in figure

3A,B and C.

(iii) The jointing between the sections shall be made with coupler plates of the

same material and thickness as the channel section. Two coupler plates, each of minimum

200mm length, shall be bolted on each of the two sides of the channel section with 8mm

dia round headed bolts, nuts and washers. In order to maintain proper earth continuity

bond, the paint on the contact surfaces between the coupler plates and cable tray shall be

scraped and removed before the installation.

(iv) The maximum permissible uniformly distributed load for various sizes of

cables trays and for different supported span are given in Table IV. The sizes shall be

specified considering the same.

(v) The width of the cable tray shall be chosen so as to accommodate all the

cables in one tier, plus 30 to 50% additional width for future expansion. This additional

width shall be minimum 100mm. The overall width of one cable tray shall be limited to

800mm.

(vi) Factory fabricated bends, reducers, tee/cross junctions, etc. shall be

provided as per good engineering practice. (Details are typically shown in figure 3). The

radius of bends, junctions etc. shall not be less than the minimum permissible radius of

bending of the largest size of cable to be carried by the cable tray.

(vii) The cable tray shall be suspended from the ceiling slab with the help of

10mm dia MS rounds or 25mmX5mm flats at specified spacing (based on Table III). Flat

type suspenders may be used for channels upto 450mm width bolted to cable trays.

Round suspenders shall be threaded and bolted to the cable trays or to independent

support angles 50mmX50mmX5mm at the bottom end as specified. These shall be

grouted to the ceiling slab at the other end through an effective means, as approved by the

Engineer-in-Charge, to take the weight of the cable tray with the cables.


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(viii) The entire tray (except in the case of galvanized type) and the suspenders

shall be painted with two coats of red oxide primer paint after removing the dirt and rust,

and finished with two coats of spray paint of approved make synthetic enamel paint.

(ix) The cable tray shall be bonded to the earth Terminal of the switch bonds at

both ends.

(x) The cable trays shall be measured on unit length basis, along the center

line of the cable tray, including bends, reducers, tees, cross joints, etc. and paid for

accordingly.

1.6.11.3 Ladder type cable tray

(i) The ladder type of cable tray shall be fabricated of double bended channel

section longitudinal members with single bended channel section rungs of cross members

welded to the base of the longitudinal members at a center to center spacing of 250cm.

(ii) Alternatively, where specified, ladder type cable trays may be fabricated

out of 50mmX50mmX6mm (minimum) angle iron for longitudinal members, and

30mmX6mm flat for rungs.

(iii) Typical details of fabrication and dimensions of both the types of trays are

shown in figure 4A,B,C and D.

(iv) The maximum permissible loading, jointing of channel sections, width of

the cable tray, provision of elbows, bends, reducers, horizontal tee/ cross junctions etc.

suspension of cable tray from the ceiling slab; painting and measurement of the cable tray

shall be as per sub-clauses (ii) to (x) below clause 2.6.11.2, except that the overall width

of one cable tray may be limited to 800mm.

1.6.11.4 Cables laid on cable trays shall be clamped on to the tray at suitable

intervals as per Table-III.

1.6.12 Cable identification tags

Whenever more than one cable is laid / run side by side, marker tags as approved,

inscribed with cable identification details shall be permanently attached to al the cables in

the manholes / pull pits / joint pits / entry points in buildings / open ducts etc. These shall

also be attached to cables laid direct in ground at specified intervals, before the trenches

are backfilled.

1.7 JOINTING

1.7.1 Location

(i) Before laying a cable, proper locations for the proposed cable joints, if

any, shall be decided, so that when the cable is actually laid, the joints are made in the

most suitable places. As far as possible, water logged locations, carriage ways,

pavements, proximity to telephone cables, gas or water mains, inaccessible places, ducts,

pipes, racks etc. shall be avoided for locating the cable joints.


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(ii) Joints shall be staggered by 2m to 3m when joints are to be done for two

or more cables laid together in the same trench.

1.7.2 Joints pits

(i) Joint pits shall be of sufficient dimensions as to allow easy and

comfortable working. The sides of the pit shall be well protected from loose earth falling

into it. It shall also be covered by a tarpaulin to prevent dust and other foreign matter

being blown on the exposed joints and jointing materials.

(ii) Sufficient ventilation shall be provided during jointing operation in order

to disperse fumes given out by fluxing.

1.7.3 Safety precaution

(i) A caution board indicating “CAUTION – CABLE JOINTING WORK IN

PROGRESS” shall be displayed to warn the public and traffic where necessary.

(ii) Before jointing is commenced, all safety precautions like isolation,

discharging, earthing, display of caution board on the controlling switchgear etc. shall be

taken to ensure that the cable would not be inadvertently charged from live supply.

Metallic armour and external metallic bonding shall be connected to earth. Where

“Permit to work” system is in vogue, safety procedures prescribed shall be complied

with.

1.7.4 Jointing materials

(i) Jointing materials and accessories like conductor ferrules, solder, flux,

insulating and protective tapes, filling compound, jointing boxes, heat shrinking joint kit

etc. of right quality and correct sizes, conforming to relevant Indian Standards, wherever

they exist, shall be used.

(ii) The design of the joint box and the composition of the filing compound

shall be such as to provide an effective sealing against entry of moisture in addition to

affording proper electrical characteristic to joints.

(iii) Where special type of splicing connector kits or epoxy resin spliced joints

or heat shrinkable jointing kits are specified, materials approved for such application

shall be used. Storing as well as jointing instructions of the manufacturer of such

materials shall be strictly followed.

1.7.5 Jointer Jointing work shall be carried out by a licensed/ experienced (where there is no

licensing system for jointers) cable jointer.

1.7.6 Cable work with joints

(i) About 3m long surplus cable shall be left on each side of joints as laid

down in clause 1.6.7.3 (viii).


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(ii) Insulation resistance of cables to be jointed shall be tested as per clause

1.8.1. Unless the insulation resistance values are satisfactory, jointing shall not be done.

(iii) Cores of the cables must be properly identified before jointing.

(iv) Where cable is to be jointed with the existing cable, the sequence should

be so arranged as to avoid crossing of cores wile jointing.

(v) Whenever the aluminium conductor is exposed to outside atmosphere, a

highly tenacious oxide film is formed which makes the soldering of aluminium conductor

difficult. This oxide film should be removed by using appropriate type of flux.

(vi) The clamps for the armour shall be clean and tight.

1.7.7 Jointing procedure

While it would be necessary to follow strictly the instructions for jointing

furnished by the manufacturers of cables and joint kits, a brief on the jointing procedures

is given for general guidance in Appendix F.

1.8 TESTING

1.8.1 Testing before laying

All cables, before laying, shall be tested with a 500V megger for cables of 1.1KV

grade, or with a 2500/5000V megger for cables of higher voltage. The cable cores shall

be tested for continuity, absence of cross phasing, insulation resistance from conductors

to earth / armour and between conductors.

1.8.2 Testing before backfilling

All cables shall be subjected to the above mentioned tests, before covering the

cables by protective covers and back filling and also before taking up any jointing

operation.

1.8.3 Testing after laying

(i) After laying and jointing, the cable shall be subjected to a 15 minutes

pressure test. The test pressure shall be as given in Table VI. DC pressure testing may

normally be preferred to AC pressure testing.

(ii) In the absence of facilities for pressure testing as above, it is sufficient to

test for one minute with 1000V megger for cables of 1.1KV grade and with 2500/5000V

megger for cables of higher voltages.


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PART A&B :TECHNICAL SPECIFICATION FOR 11 / 22 kV XLPE POWER CABLE (CROSS LINKED POLYTHELENE DRY GAS CURED) IS IN SEPARATE PDF DOCUMENT


Page 75 of 95

PART-C TECHNICAL SPECIFICATIONS FOR 11kV FAULT PASSAGE

INDICATOR (FPI) with RTU

3.1 SCOPE:

Supply of overhead Fault Passage Indicators (FPI) for overhead lines to be installed on 11 KV lines.

The objective of this remote communicable FPI is to quickly identification of the faulty circuit and

automatic update to the SCADA control center over remote communication.

3.2 PURPOSE:

To locate the exact passage of faults on overhead lines. The FPI shall indicate both transient as well

as permanent faults on the O/H lines

3.3 OPERATION:

The Fault Passage Indicator shall operate on either passing over of the absolute threshold current

(user settable) or the current variation (di/dt).

Upon the installation of the indicator, the FPI shall adjust itself to the network frequency and voltage

of perform required function.

3.4 FAULT TYPES:

The FPI shall detect and indicate both earth faults as well as phase to phase faults. In addition to this,

the FPI shall also detect and indicate transient and permanent faults.

3.4.1 INRUSH RESTRAINT:

The FPI shall be equipped to filter out the inrush current due to transformer magnetizing currents

thus avoiding the possible false indication of faults.

3.4.2 RESET:

Once the fault is cleared, the FPI shall reset itself upon the power return, it shall also have a facility

of resetting with settable time duration and the manual reset.

3.5 TRANSIENT FAULT EVOLUTION:

If FPI is busy in flashing on transient fault and if the permanent fault occurs, the FPI shall

automatically change the priority and shall start flashing differently to show the permanent fault;

thus helping maintenance crew to review the priorities.

Salient Technical Features of FPI

Offered 11 kV Clip-on / Pole mounting, Remotely monitored ,Outdoor unit Fault Passage Indicator

(FPI) should have compatibility with OPEN PROTOCOL SCADA system.

1. It should operate on either passing over of the absolute threshold current (user settable) or

the current variation(di /dt)

2. It should adjust itself to the network frequency and voltage to perform required function.

3. It should detect and indicate both earth faults as well as phase to phase faults


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4. It should also detect and indicate transient and permanent fault

5. It should be equipped to filter out the inrush current due to transformer magnetizing

currents thus avoiding the possible false indication of faults

6. Once the fault is cleared, the FPI shall reset itself upon the power return. It shall also have a

facility of resetting with settable time duration and the manual reset

7. If FPI is busy in flashing on transient fault and if the permanent fault occurs, the FPI shall

automatically change the priority and shall start flashing differently to show the permanent

fault; thus helping maintenance crew to review the priorities

8. The lithium battery provided inside the FPI should be trouble free of 10 years life and

replaceable type, in the case of battery failures and

9. 9.The FPI should have some self-test possibility usable when the FI is on the line (powered or

not)

10. Installation of FPI should be possible on live lines using an isolated hot stick with shot gun

type termination

11. It should support communication system SNMP, Master station(s) using 60870-5-

104protocol, protocol over GPRS/CDMA, , and forming IPSec VPN based security.

3.6 RTU for FPI:

The RTU should enable the communication, one side with the FPI units, via a spread spectrum

license-free radio frequency with low power consumption and the other side with the distant

acquisition system through a long range communication medium over mobile telephone network

(3G/GPRS/CDMA) others via the local RS232 port. The RTU should be capable of forming IPsec VPN

connectivity.

3.6.1 Basic Functions

The RTU should be able to store the date and time stamping of all events from communicable FPI

and send all requested events to the SCADA application. This RTU should have the facility to change

the FPI setting over remote operation. This RTU should have the memory capacity to store last 100

stamped events.

3.6.2 Description

The RTU should be available in a Pole-mounted enclosure, able to house a battery and a battery

charger, with external AC supply.

The main board includes:

• A short range low power spread spectrum radio for communication with the FPI

� For long range communication:

• One communication medium with its embedded modem (GPRS/CDMA) or o one RS232 port

for external communication.

• One RS232 local parameter setting port

• 6 digital inputs, for alarm information to SCADA application


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• 3 digital dry contact outputs set to repeat phase faults (phase A, B, or C) from FPI or short

range communication faults or battery faults for transmission by an external RTU.

3.6.3 Detail Characteristics

Sr.

No.

Details Specific Requirement

1 Type Spread spectrum low power licence-free

2 Frequency Free Band allowed in India

3 RF output FCC part 15.249 and AS/NZS 4268:2003 approved radio.

4 Communication media Embedded GPRS modem

5 Communication protocol DNP3, IEC 870-5-103/104

6 Type I(min), I(max), I(mean) and I(inst)

7 Number of HV lines monitored

per RTU

9 phases

8 mechanical Large enclosure

Small box Cabinet

100 m

9 Earth fault indication (phase A, B, or C), (beginning time, ending time)

10 Phase fault or Imax b Phase fault indication (phase A, B, or C), (beginning time,

ending time)

11 Transient fault detection if

enabled

Transient fault indication and time stamping

12 Voltage loss indication Voltage loss indication (phase A, B, or C) and time stamping

and Voltage recovery time indication

13 Equipment monitoring Equipment monitoring

14 Local radio communication

faulty

Communication with FPI Nos. XX faulty (after a number of

attempts) and time stamping

15 FPI battery alarm Battery low in FPI no.x and time stamping

16 RTU battery alarm Battery low in RTU and time stamping

17 AC supply alarm AC supply alarm External AC supply off

18 Inputs 6 digital inputs

19 Outputs 3 relay outputs 220 Vac/1 A

20 Local archive of Date and time

stamped events and measures

100 events

21 Downloading of local archive Remote via SCADA application

22 Power supply In built Battery of suitable rating

23 Operating temperature -25°C to +70°C

24 Storage temperature -40°C to +85°C

25 Mechanical Large enclosure

Small box Cabinet

Mechanical Large enclosure Small box Cabinet

26 Dimensions in cm 430x330x200

27 Net weight in kg 8 kg

28 Protection level IP 54


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29 Standards Standards

30 Vibrations and shocks test IEC 68-2-6 and 68-2-29

31 EMI/EFI immunity IEC 801-3 and FCC Part 15

32 Salt spray and humidity tests IEC 68-2-11 and 68-2-30

TECHNICAL DATA for FPI

No. Nominal operation Voltage 4 to 66 kV

1 Power Frequency 50 Hz

2 Conductor diameter 5 to 30 mm

3 MV neutral arrangement Independent / Solidly earthed

Fault Detection Parameters

4 Di trigger setting 6-12-25-60-90-120-160A-Off

5 Current setting trigger value 100-200-500-800A

6 Transient fault detection On / Off facility required

7 Flash duration (user settable) 2-4-8-16 hours

8 Inrush transient duration 3 Sec

9 Loss of voltage condition U < 45% Un

10 Fault confirmation Voltage drop within 70s after fault detection

Reset (Permanent Faults)

11 Automatic power return reset U > 70% Un during 70S

12 Timer reset 4-16 hours

13 Manual reset By magnet

Fault Indication

14 Indication Red flash light

15 Light power 40 Lumens

16 Visible angle 360 deg.

17 Standard total flash duration 400-800 hours

18 Battery Lithium with life > 10 years

Environment

19 Operating temperature 0 to +85 deg. C

20 Storage temperature 0 to +85 deg. C

21 Protection level IP 54 IK7

Test

22 Short circuit withstand 25 KA / 170 ms

23 Dielectric test 125 KV

Site Condition

25 Ambient Temperature 0-50 deg C

26 Relative humidity 10-100%

27 Average annual rainfall 750 mm

28 Altitude 300 m Max

29 Wind pressure 195Kg/m2 upto 30m

Technical description

30 Rated operating voltage 11 kV

31 Rated frequency 50 Hz

32 Trip current 30-500A


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33 Fault current minimum duration 50 ms

CODES AND STANDARDS:-

The equipment proposed to be designed, manufactured and tested in compliance with the latest

version of IEC Standards.

Electro-magnetic compatibility IEC-61000-6-2 and FCC part 15

IP65 Protection level IEC-60529

Damp Heat cycle Test (Humidity & Heat cycle ) IEC-68-2-30

Salty fog IEC-68-2-11

Sinus wave vibration & Shocks IEC-68-2-6 , IEC-68-2-29

Dielectric Test IEC 60060-1

Temperature aging IEC-68-2-14

Short circuit ANSI 495 (part 4.4.8)

EMI / EFI immunity IEC -801

Device Enclosure IP 65

SCADA compatibility of FPIs: -

The FPI should be provided with provision of necessary terminal blocks which shall be used for

connecting the RTUs for automations as mentioned in below table:

O/C operated Potential free contact

E/F operated Potential free contact

Fault passage indicator OK Potential free contact

Command for reset FPI Potential free contact


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PART-D. Pole Mounted Load Break Switches / Sectionalizers with

Integrated remote communication capabilities

2.12 SCOPE

This specification covers requirements for outdoor Pole-mounted load break switches /

sectionalizers that have programmable fault detection and sectionalizer features,onload operable ,

and that are intended for source and down-line duty on rural distribution networks at nominal A.C.

voltages of 15 kV.

The 11kV sec. Should be provided with potential free contacts and control contacts (suitable

connector) for SCADA remote (FRTU) integration. Refer Annexure-1.

230V AC Supply for charging of FRTU battery should be available. FRTU will require power up to 60

VA.

2.13 NORMATIVE REFERENCES

The following standards contain provisions that, through reference in the text, constitute

requirements of this specification at the time of publication the revisions indicated were valid. All

standards are subject to review and parties to purchasing agreements based on this specification are

encouraged to investigate the possibility of applying the most recent revisions of the standards listed

below.

IEC 60265-1 High Voltage Switches

IEC 60529:1989, Degrees of protection provided by enclosures (IP Code).

UNIPEDE NORM (SPEC) 13 (1995): Automation and Control Apparatus for Generating Stations and

Substations: Electromagnetic Compatibility Immunity Requirements.

2.14 DEFINITIONS AND ABBREVIATIONS

2.14.1 Automatic Detection Group Selection (ADGS):

An automated feature to determine and activate a pre-programmed group of detection settings

based on the direction of power flow.

2.14.2 Auto-recloser (AR):

A mechanical switching device that, after opening, closes automatically after a predetermined time.

2.14.3 Cold load pick-up (CLP) feature:

A feature that allows modification of the over-current fault detection characteristics in order to

prevent false fault detection under conditions of system energisation.

2.14.4 Dead time:


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Also referred to as "Reclosing Interval". This is the time between the instant that the current is

interrupted by the AR and the instant the contact of the AR closes as a result of an automatic reclose

operation.

2.14.5 Definite time:

A fault detect event occurs if the current exceeds the fault threshold setting for a time equal to the

definite time setting.

2.14.6 Effectively earthed system:

An earthed system in which the healthy phase power frequency phase-to-earth over voltages

associated with earth faults are limited to 80% of the highest phase-to-phase voltage of the system.

2.14.7 Pickup:

The fault detection elements are monitored and an element “picks up” when the measured current

exceeds the preset level of the specific element. Typical detection elements are Phase, Earth and

Sensitive Earth Fault (SEF).

2.14.8 Pole-mounted remote terminal unit (PMRTU):

A remote terminal unit that is designed for pole mounting and that operates specific polemounted

equipment remotely.

2.14.9 Sequence reset time:

The time duration after a supply interruption occurred before the sectionalising sequence resets if

the Sectionalizer does not detect another fault.

2.14.10 Sectionalizing:

The ability of the load break switch to count the operations of an upstream AR and to open during

the dead time of the AR after a configurable number of supplies interrupts.

2.14.11 Secure control:

A single mechanically non-latching switch that effects one state of a control function only. An

example of which is either a non-latching switch or two separate push buttons that affect one state

of a control function only in each position. If a control is activated repeatedly it only effects that

state and does not change the state of the control.

2.14.12 Sensitive earth fault (SEF):

A relay that is sensitive to very low earth fault currents and in which the operating settings are for

current magnitude and definite time delay.

2.14.13 Supervisory:

Remote control and indications of an LBS or a FRTU by means of a telecommunications link.

2.14.14 Supply Interruption:


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A fault pickup followed by a “no current” and “no voltage” condition is called a Supply

Interruption. This condition typically occurs when an upstream recloser trips due to a downstream

fault.

2.14.15 Toggled control:

A single mechanically non-latching switch/push-button that enables a single control function on the

first operation of the switch/push-button and disables the function on the second operation of the

same switch/push button.

2.15 REQUIREMENTS

2.15.1 General

The load break switch / Sectionalizer shall be suitable for use on non-effectively earthed and

effectively earthed networks and under the system conditions and service conditions as

follows:

a) Nominal system voltage (U) (r.m.s.) - 11 kV;

b) Load current - 630 A;

c) Fault make capacity (r.m.s.) 16 kA;

d) Lightning Impulse Withstand Voltage (BIL) - 125 kV

e) System frequency - 50 Hz;

f) Number of phases - 3;

g) Interrupting medium - Puffer

h) Insulation medium - SF6

i) Minimum no load mechanical operations - 3000

j) Minimal number of rated load operations - 600

k) Operating Mechanism - LV motor

l) Altitude - up to 3000 m;

(For altitudes above 1000m derate in accordance with ANSI C37.60)

m) Ambient temperature minimum - -30°C;

maximum - 40-45 °C;

n) Maximum daily variation - 35 °C;

o) Pollution level - medium/heavy


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(special applications);

p) Lightning activity - high.

2.15.2 Mounting

2.15.2.1 The LBS shall be suitable for single pole/DP mounting. The recloser

shall be mounted on channel on D.P. Structure.

2.15.2.2 Adequately rated lifting eyes shall be provided and they shall be

designed to allow the completely assembled LBS (surge arresters

fitted) to be lifted without recourse to a sling spreader. The diameter of

the eyes shall be a minimum of 30mm.

2.15.2.3 Suitable mounting brackets for surge arresters shall be provided on

the line side and on the load side of the LBS, adjacent to the bushings.

2.15.2.4 The LBS shall be fitted with an external M12 earthing stud, complete

with a nut, lock nut and spring washer. The earth stud shall be welded

to the tank for optimal earthing connection.

2.15.2.5 Each bushing of the LBS shall be marked x, xx and xxx for the normal

line side and I, II and III for normal load side.

2.15.2.6 A detailed drawing of the single pole LBS mounting arrangement with

surge arresters fitted shall be provided. The minimum phase-to-earth

clearances shall be indicated on the drawing.

2.15.2.7 The mass of the mounting hardware, the LBS and the control cabinet

and cable shall be stated in the tender documentation.

2.15.3 Bushings

2.15.3.1 Terminals

The preferred arrangement for termination is an insulated bushing arrangement achieved by using

epoxy resin bushings and silicone rubber bushing boots together with 3 meters XLPE insulated water

blocked cable tails.

2.15.3.2 Material

The following bushing materials are acceptable:

� Aromatic epoxy resin with Silicone rubber boots Porcelain bushings and EPDM rubber are

not acceptable.

Details of the type and creepage shall be provided in the tender documentation. Minimum

acceptable creepage is 770 mm.

2.15.4 Finish

2.15.5 All interior and exterior ferrous surfaces of the LBS and control cabinets shall be

manufactured from 316 marine grade stainless steel. All support structures and

associated bolts and nuts with these parts, shall be hot-dip galvanized.

2.15.6 Suitable precautions shall be implemented to prevent corrosion due to the use of

dissimilar materials.


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2.16 CONTROL EQUIPMENT

2.16.1 Control cabinet

2.16.1.1 Cabinets that house equipment for protection and control shall be mounted independently

of the LBS.

2.16.1.2 Suitable ultraviolet-resistant cable,7 m long, shall be provided to connect the LBS to the

control cabinet. If shorter or longer cables are required, the length will be specified in the

tender documentation.

2.16.1.3 It shall be possible to disconnect the cable at the LBS while the LBS is connected to the

power system, without causing damage or malfunction: care shall be taken that CTs are not

open circuited. A robust, multipin weatherproof connector shall be supplied. The female

part of the connector shall be mounted on the LBS and the male part shall be mounted on

the cable. Preference will be given to products supplying connectors at both the LBS and

the control cabinet.

2.16.1.4 Cabinets shall be adequately sealed and dust protected and shall be internally treated to

prevent moisture condensation. The degree of protection shall be suitable for purpose.

2.16.1.5 The supplier shall ensure that the equipment housed in the control cabinet can withstand

the heating effect of direct solar radiation without causing failure and/or malfunction.

Details shall be provided in the tender documentation.

2.16.1.6 The cabinet shall make provision for bottom entry of three cables. This shall be done with

pre-punched holes, two 21 mm and one 32 mm in diameter. The holes shall be suitably

blanked off.

2.16.1.7 The cabinet shall be fitted with an external M10 earthing stud with a nut, lock nut and a

serrated washer.

2.16.1.8 The door of the cabinet shall be fitted with a robust fastening arrangement that is capable

of being secured by a padlock that has a shackle of 8 mm diameter.

2.16.1.9 The cabinet shall be easily removable for workshop repair purposes.

2.16.1.10Electronic control equipment

2.16.1.11The controls shall not suffer any damage if one or more polesof the load break switch fail

to respond to either a trip or a close command.

2.16.1.12 Electronic modules shall perform continuous diagnostic monitoring and shall contain

hardware and software watchdog checking.

Space required for mounting FRTU Panel. Dimensions details for FRTU are about 1000Hx600Wx300D

2.17 DETECTION CHARACTERISTICS

2.17.1 General

2.17.1.1 The following detection elements shall be available: over-current

(O/C), earth fault (E/F) and sensitive earth fault (SEF).

2.17.1.2 Each of the detection elements is monitored with independent definite

time settings as per relay coordination calculation w.r.t. concern S/s and fault thresholds.


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2.17.1.3 The ratio of drop-off current to pick-up current shall be at least 90% for

all detection functions.

2.17.1.4 The SEF function shall be equipped with harmonic filtering to prevent

operation when harmonics are present in the primary residual earth

currents. A low pass filter with 3rd harmonic rejection > 28dB shall be

supplied. Both the SEF function and its filter shall be described in the


2.17.1.5 The LBS and Control element shall support multiple detection groups

and this shall meet the requirements specified below:

� The LBS shall have a minimum of 4 independent detection groups. The Detection Groups

shall have clear indication and shall be marked as "I, II, III, IV" or "A, B, C, D"

� Each detection group shall have the facility to configure O/C, E/F and SEF fault detection

current and definite time. The detection parameters used in one of the detection groups

shall be available for use in any or all of the other detection groups.

� Changes to any of the detection parameter of the non active detection group shall not affect

the detection functionality of the active detection group.

� Information about activation of any of the detection groups shall be recorded in history and

shall be easily assessable. Information about fault detection shall clearly indicate the

detection group active at the time of a fault.

� LBS and Control element shall have the facility for Automatic detection group selection.

Automatic Detection Group Selection shall have the facility to be turned ON or OFF with

password protection or other form of access control.

2.17.2 Over-current (O/C) element

2.17.2.1 The over-current pick-up setting range shall be selectable from 10 A to

1260 A in the steps not greater than 10 A.

2.17.2.2 The Definite Time for fault to persist setting range shall be selectable

from 0.05 to 100.0 sec in the steps not greater than 0.1 sec.

2.17.2.3 A cold load pick-up (CLP) feature shall be provided that allows user

selectable modification of detection element characteristics under

conditions of system power restoration.

The pick-up current setting of the O/C element may be modified with a settable factor to increase

the pick-up current for the CLP duration.

The CLP function shall have the following characteristics:

• the CLP function shall not in any way interfere with any of the other

functions‟ / elements' pick-up current settings except as mentioned above;

• the CLP functionality shall be such that the active duration of the CLP is

selectable from 0 min to 200 min in 1 min steps; and

• the modification factor should be settable from 1 to 5 in steps of 0,1.

2.17.3 Earth fault (E/F) element


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2.17.3.1 The earth fault setting range shall detect primary earth fault currents

down to 20 A. The E/F pick-up setting range shall be selectable from

20 A to 1260 A in the steps not greater than 10 A.



2.17.4 Sensitive earth fault (SEF) element

2.17.4.1 A primary earth fault current of 4A to 20A in steps not exceeding 1A

shall be detectable.



2.17.5 Sectionalising Functions

2.17.5.1 The number of detected faults to trip shall be selectable to be 1, 2, 3 or 4.

2.17.5.2 The sequence reset time shall be selectable from 5s to 120s in 1s steps.

2.18 STATISTICAL MEASUREMENT FUNCTIONS

2.18.1 The characteristics of the statistical measurement functions shall be as follows

2.18.1.1 Measurement shall be done with one of the following methods:

� three-phase-3-wire method; and

� or the three-phase-4-wire method

2.18.1.2 Quantities to be measured/calculated with specified accuracy are:

� r.m.s. phase-to-phase and phase-to-ground ±2.5%;

voltage of all three phases (% of rated voltage):

� r.m.s current per phase ± 2.5%;

(within rated current range):

� three phase active power in kW: ± 5%;

� three phase reactive power in kVARs: ± 5%;

� total three-phase active energy in kWh: ± 5%;

� Power factor: ± 5%;

� Maximum demand ± 5%.

2.18.1.3 The real power energy and maximum demand measurement shall be

integrated with respect to time. Energy values shall be calculated with

selectable time integration periods of 5 min, 15 min, 30 min or 60 min.


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The data buffer shall work on the FIFO principle and a minimum size

for the data buffer shall store values for 4 months on the 30 minutes

integration period.

2.18.1.4 The voltage factor of the voltage transformers shall be a minimum of 1.9

2.18.1.5 LBS and Control element shall have the facilities to record the

cumulative number and duration of outages. The information shall be

assessable locally or remotely using a SCADA system. The following

parameters shall be recorded:

� Cumulative total number of outages;

� Cumulative total outage duration; and

� Time and duration of each outage in the form of an event log.

2.19 LOCAL CONTROL AND INDICATION

2.19.1 The local control and indication shall be as given in Table 1.

Table 1: Minimum specification of local controls and indications

1 Item 2 Features 3 Remarks

Local control (See Note 1) Local/Remote 2 position key switchable

Load break switch open Secure control (Note 3)

Load break switch close Secure control (Note 3)

Sectionalizer ON/OFF Secure or Toggled control.

Local indication (See Note 1) Local/Remote See Note 3

Load break switch open

Load break switch closed

Sectionalizer trip

Sectionalizer ON/OFF

Controller not healthy See Note 2

SF6 Alarm

O/C operated

E/F operated See 2.19.9

AC fail

DC abnormal See 2.24.5.3

DC fail

Charger fail

2.19.1.1 Notes (preferable)

Note 1: The local control and the local indication features on the control panel shall be labeled as

presented in column 2, where applicable. The type of switch used for local control shall not

allow for a conflict to exist between the switch position and the function status.

Note 2: The 'Controller not healthy' indication shall indicate the control equipment not healthy

(watchdog) function operated. It shall not operate during the normal polemounted switch


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operating cycle. This indication should remain active until the unhealthy state that initiated it

returns to normal.

Note 3:The two-position switch (labeled as below) shall allow the LBS controller to be set in the

following modes:

Remote: In this mode a local operator can trip the LBS and change the mode. A remote operator can

trip or close the LBS.

Local: In this mode a local operator can trip and close the LBS. A remote operator can only trip the

LBS.

2.19.2 All local controls and indications shall be accessible in adverse weather condition.

2.19.3 The LBS shall be provided with external levers to permit manual operation, using an

insulated operating stick, to open, close, lock-out and reset the LBS from ground

level. Where these operations can be performed at the control cabinet, it shall only

be necessary to provide a mechanical means to open and lockout the load break

switch using an insulated operating stick.

2.19.4 The LBS status shall be clearly visible from ground level. "Opened" shall be indicated

with a green "OFF". A red "ON" shall indicate "Closed". Alternative indications shall

be subject to approval by the purchaser.

2.19.5 Pressure relief facilities shall be provided to enable the LBS to withstand safely the

effects of excessive pressure rise due to an internal fault.

2.19.6 Malfunction of the LBS shall not pose a safety hazard to the operator due to the

recoil or backlash of items such as external operating rods, cranks and levers.

2.19.7 Easily available (i.e. maximum of one keystroke) local indication of detection

operation shall be provided for at least the last operation of the LBS. The function,

phase involved and the current magnitude shall be indicated.

2.19.8 Switches used for local control shall offer the type of control described in table 1 i.e.

secure or toggled control. Electronic keypad controls shall offer 'quick key' (maximum

of one keystroke) access to the controls in Table 1 if not implemented with switches.

2.19.9 LBSs using SF6 as an arc extinguishing medium shall:

2.19.9.1 Provide a low gas pressure indication at a gas pressure that enables

safe operation of the LBS;

2.19.9.2 Be provided with a method of inhibiting any operation of the LBS in the

event of the gas pressure dropping below a safe pressure.

2.20 REMOTE CONTROL AND INDICATION

2.20.1 The remote controls and indications shall be as given in Table 2. and Annexure-1

Table 2: Minimum specification of remote controls and indications

1 Item 2 Features 3 Remarks

Remote control Load break switch open Secure

control

Load break switch close Secure


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control

Sectionalizer ON/OFF Secure

control

Remote

indication

Local/Remote (See Note 5)

Load break switch open Load break switch closed Sectionalizer trip

Sectionalizer ON / OFF

Sectionalizer trip (See Note 6)

SF6 Alarm

O/C operated

E/F operated See 2.19.9

A.C. fail

D.C. abnormal

D.C. fail See 2.24.5.3

Charger fail

Analogue indication:-

• r.m.s. phase-to-phase and phase to ground voltage of all three phases

• r.m.s current per phase three-phase active power in kW

• three-phase reactive power in kvars total three-phase active energy in kWh

• Power factor

• Maximum demand

2.20.1.1 Notes (Preferable)

Note 4: The two-position switch (labeled as below) shall allow the LBS controller to be set in the

following modes:

Remote: In this mode a local operator can trip the LBS and change the mode.

A red in the mote operator can trip or close the LBS.

Local: In this mode a local operator can trip and close the LBS. A remote operator can only trip the

LBS.

Note 5:The LBS indication shall give an alarm with any Sectionalizer attempt.

Note 6 : The MFT is not required in the scope however CT and PT is required as per the detail

Specification.

Current Transformers for breaker

CT Type :Tape wound

CT Description :The CTs of breaker shall be suitable for sensing the minimum primary variable

current in the order of 10-100 A and the secondary current for the CT is 1 A. The CT

shall be housed in outside SF6 chamber for testing and Maintenance.


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Rated burden : Suitable for self powered relay and metering

PT : PT should be provide as per our requirement mention in power supply 2.24

2.21 OPERATION INTERLOCKING

Prevent the removal of respective cable covers if Isolator is ‘ON’- Electrical/Mechanicaland

Prevent the closure of isolator or circuit breaker if respective cable cover is open-

Electrical/Mechanical.

2.21.3.1 All operating, detection and communications parameters.

2.21.3.2 An event record containing at least 3000 events (a detection event is

defined as all operations in a sequence until successful sequence

reset or sectionalizer trip). The actual number available shall be stated

in the tender documentation.

2.21.3.3 Refer to 2.18.1.3.

2.21.3.4 Maximum demand information. Maximum demand shall have the

facilities to be configured for weekly and/or monthly demand.

2.21.4 A pointer shall be provided to indicate up to where the data was last read. This will

enable regular uploading of the data without re-loading of previously read data.

2.21.5 All events shall be time and date stamped with a resolution of at least 10ms relative

to the onboard clock.

2.24 POWER SUPPLIES

2.24.1

2.24.2 Primary supply: Preference will be given to the ability to obtain primary power directly

from the HV power system requiring no additional primary supply connection.

2.24.3 Test supply: The LBS shall accept an external AC 230 V 50 Hz supply.

2.24.4 Optional supply: The LBS shall accept an external DC 110 V supply.

2.24.5 Auxiliary supply: An auxiliary supply with the following minimum characteristics shall

be provided:

2.24.5.1 One battery and constant voltage charger with current limiting shall be

part of the LBS. Battery standby time shall not be less than 24 h,

allowing for ten LBS operations and a Transmit : Receive : Standby

duty cycle of 5:5:90 from a 5 W output radio. The battery shall

recharge to 80% of its capacity in a maximum of 15 h. The total

number of LBS operations under the above communications scenario

shall be at least 10. Details will be stated in the tender documentation.

2.24.5.2 Batteries shall be disconnected at the manufacturer's specified

minimum voltage.


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2.24.5.3 'Battery Low' indication shall be available locally and remotely and

shall include a battery test. The indication of "Battery Low" status shall

allow for a further ten LBS operations.

2.24.5.4 The minimum battery life expectancy shall be 5 years. Details of the

guaranteed life expectancy of the battery shall be stated in the tender

documentation.

� 230V AC Supply for charging of FRTU battery should be available. FRTU will require power up

to 60 VA.

2.25 MAINTENANCE AND COMMISSIONING

2.25.1 All the communications equipment shall be easily accessible in the control cabinet. Wiring of

communications links in the control cabinet shall permit the connection of a temporary

protocol-monitor. It shall be possible to perform secondary injection testing while the LBS is

communicating with the Centre.

2.25.2 It shall be Possible to disconnect the LBS and connect a simulated switch to the control

cabinet for testing purposes.

2.25.3 The LBS shall not malfunction while the radio is transmitting via an antenna in close proximity

and the control cabinet door is open.

2.25.4 Provision shall be made in the control cabinet for isolating the power supply to/from the

following:

� battery;

� battery charger;

� Primary supply to the control cabinet electronics.

2.26 RATING PLATE

Each LBS shall bear a rating plate of an intrinsically corrosion-resistant material, indelibly marked

with the sea-level rating for which the equipment has been type tested. The rating plate shall be

indelibly marked with:

� the manufacturer's name;

� the equipment type designation and serial number of the LBS;

� the mass, in kilograms;

� the date of manufacture; and

� Auxiliary supply voltage (if applicable).

2.27 ADDITIONAL INFORMATION

The following shall be submitted with the tender.

2.27.1 Load break switch details

� manufacturer;


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� type designation;

� place of manufacture;

� fault make capacity; 3s 1s nd

� Critical current (maximum instantaneous peak).

2.27.2 A schematic-wiring diagram of the LBS offered.

2.27.3 A general-arrangement drawing of the LBS offered.

2.27.4 Details of the maintenance and operating equipment, procedures needed and a

detailed parts list of the various components.

2.27.5 A description of the LBS operation, with instruction and maintenance manuals,

including maintenance schedules, fault detection characteristics, communications

facilities, the method of applying settings and controls, together with any software required

and the cost thereof. The software requirements shall be stated in the tender

documentation.

2.27.6 Details and the cost of any available portable calibration and diagnostic test set that may be

used to perform the functionality described in 2.24.1, 2.24.2 and 2.24.3. Details of the test

set shall be given in the tender document.

2.27.7 A list of recommended spares and tools.

2.27.8 The method of changing detection settings shall be stated in the tender documentation.

2.27.9 Details of technical back-up facilities available. These details shall be stated in the


2.27.10 Details of the class, ratio(s) and burden of the detection current transformer

and voltage transformer, if supplied, shall be stated in the tender documentation.

2.27.11 The supplier shall include the following details of measurement current

transformers (not internal to the LBS) that can be supplied with the LBS. The

following details shall be provided:

� available ratio(s) and accuracy class; method of fitting; and

� effect on creepage distance and BIL

2.27.12 Where applicable details of the low gas pressure alarm/lock-out philosophy;

2.27.13 Details of LBS service history:

� how many in service, where and for what period; and

� Contact names and numbers.

2.27.14 Details of LV trip/close motor if available as an option

2.27.15 Power requirements for a close operation

2.27.16 The maximum achievable separation between the control unit and the load break switch.

2.27.17 Full details of the protocol implementation and the complete point database.


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2.28 TESTS

2.28.1 Type tests

The load break switch / sectionalizer shall have been type tested in accordance with, and found to

comply with, the requirements of IEC 60265-1 for the following, and the appropriate values shall be

stated in the tender documentation:

2.28.1.1 Operating duty.

2.28.1.2 Making current.

2.28.1.3 Insulation (dielectric tests).

2.28.1.4 Radio interference voltage.

2.28.1.5 Temperature rise.

2.28.1.6 Mechanical operations.

2.28.1.7 Control equipment surge withstand capability.

2.28.2 The control cabinet and associated electronics shall have been type tested in accordance with

UNIPEDE NORM (SPEC)13 (1995): Automation and Control Apparatus for Generating Stations

and Substations: Electromagnetic Compatibility Immunity Requirements. The environment

shall be considered as falling in the HV substation category, according to NORM (SPEC)13.

2.28.3 Test records (on identical equipment) in the form of validated copies of test certificates issued

by a recognized testing authority shall be submitted with the tender documentation.

2.29 ROUTINE TESTS

2.29.1 Routine tests, as required in the relevant standards, shall be carried out as a

normalrequirement of the contract and, unless otherwise agreed upon, shall be witnessed by

the purchaser or by his appointed representative. No additional charge shall be levied for such

tests or for the production or presentation of documentation related to routine tests.

2.29.2 Duplicate copies of routine test certificates shall be supplied together with the equipment

when the latter is delivered to the final destination stated in the order.

2.30 PACKING/DOCUMENTATION

2.30.1 Packing

All equipment shall be carefully packed to prevent damage or deterioration during normal

transportation, handling and storage.

Each container shall bear the following information on the outside of the container:

� The address of the destination

� The gross mass, in kilograms

� The name of the manufacturer

� The purchaser's order number and port of destination

2.31 DOCUMENTATION

Each LBS shall be supplied complete with the documentation specified in Items 2.27.1,

2.27.2, 2.27.3 and 2.27.4, together with the routine test certificates specified in 2.29


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ANNEXURE 1

FRTU requirements with respect to RMU/Sectionalizer A. Introduction: The purpose of the document is to specify FRTU requirements with respect to RMU/Sectionalize requipment. The requirements can be broadly specified as; 1. Space for mounting FRTU. 2. Mounting holes. 3. ‘SCADA Interface’ module. 4. 230VAC auxiliary power source with earthing point. All these are to be provided in RMU/Sectionalizer Cabinet/Panel.

B. Mounting requirements: For the purpose of safety and compactness it is required that FRTU be mounted in RMU/Sectionalizer cabinet so, suitable mounting space for FRTU to be provided inside cabinet. The size of FRTU and typical arrangement of FRTU is as shown in Appendix-1. Since the FRTU will be mounted inside the panel, mounting holes are to be provided. The mounting holes can be provided on a mounting plate or any other suitable arrangement. The details of mounting holes are shown in Appendix-1.

C. Connectivity requirements: The connectivity of signals between FRTU and RMU/Sectionalizer is required to be hardwired instead of serial communication. The disadvantages of serial communication are; 1. Increase in response time due to additional poll based monitoring and control. 2. Single point of failure.


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3. Dependency on additional component (RMU/Sectionalizer IED). 4. Troubleshooting is complex than hardwired signals. 5. Maintenance issues considering above points in large number of RMU/Sectionalizer locations. Since connectivity of FRTU with the RMU/Sectionalizer will be hardwired signals, all the I/O signals required for SCADA are to be terminated on the ‘SCADA Interface’ module. The ‘SCADA Interface’ and its typical arrangement are as shown in Appendix-1. Typical list of I/O signals required for SCADA is shown in Table-1. The material required to be provided is as shown in Table-2.

Documents

PART A&B: TECHNICAL SPECIFICATION FOR OUTDOOR 11 KV … · SF6 insulated VCB of suitable rating - e) 6-way ,11KV Gas (SF6) Insulated RMU with 3Nos 630A Load break switches and 3Nos