HARYANA VIDYUT PRASARAN NIGAM LIMITED

HARYANA VIDYUT PRASARAN NIGAM LTD.xe "HARYANA VIDYUT PRASARAN NIGAM"SPECIFICATION NO. SSD/S-08/DGM-1386 xe "Specification No. HGD/S713/DGM86"TECHNICAL SPECIFICATIONxe "TECHNICAL SPECIFICATION"FORxe "FOR"40/50MVA, 132/33 kV POWER TRANSFORMERxe "36 kV VACUUM CIRCUIT BREAKERS" CHIEF ENGINEER/MM,xe "Chief Engineer/D&P,"

HVPNL, SHAKTI BHAWAN,

SECTOR-6, PANCHKULA. xe "Haryana Vidyut Prasaran Nigam"xe "Haryana. (INDIA)"

JULY-2012

TECHNICAL SPECIFICATION FOR

40/50 MVA 132/33kV

POWER TRANSFORMER

1.00SCOPE:

a)This specification covers the Design, Engineering, manufacture, testing, supply on CIP basis, transportation to site, insurance, storage, testing and commissioning of 40/50 MVA 132/33 kV Power Transformers.

b)All drawings, schedules and annexures appended to this specification shall form part of the specification and supplement the requirements specified. The equipment/materials offered by the Bidder shall be complete in all respects and, whether called for specifically or not, all accessories, hardware and services required for normal satisfactory operation of the system shall be deemed to be included in unit rates quoted. Design and manufacture shall also be such that equipment/ accessories of the same type and rating would be interchangeable.

Specific reference in this specification and documents to any material by trade name, make or catalogue number shall be construed as establishing standard of quality and performance and not as limiting competition. All equipment/ accessories offered shall also be of proven design and manufacture. The make of all accessories and hardware shall be subject to purchasers approval.

2.00CODES & STANDARDS:

All standards, specifications and codes of practice referred to herein shall be the latest editions including all applicable official amendments and revisions as on date of opening of bid. The following standards and codes shall be applicable: -

IS:5

Colour for ready mix paints.

IS:325

Three phase induction motors.

IS:335

New insulating oils for transformer.

BS:148/IEC-296

IS:375Marking & arrangement of Switch-gear bus bars main connections and auxiliary wiring.

IS:1866Code of practice for maintenance of insulation oil

IS:2026Specification for Power Transformers.

&IEC:76

IS:2099Bushing for alternating voltages above 1000 volts

& 3347

IS:2147Degree of protection provided by enclosures for low voltage switchgear & control gear.

IS:2705Current transformer

IS:3637Gas operated relay.

IS:3639Fittings and accessories for Power Transformers.

IS:6600 Guide for loading of oil immersed transformers.

&IEC-354

IS:8468 On load tap changer.

&IEC:214

IS:5561Electric power connectors.

IS:617Aluminium Alloy grade.

IS:2629Recommended practice for hot-dip Galvanising.

IS:8478On load tap changer application guide.

IS:8603Dimensions for porcelain transformer bushings for use in heavily polluted atmosphere(36 kV Class). Dimensions for oil filled porcelain transformer bushings for use in medium polluted atmosphere.

IS:9434Guide for sampling and analysis of free and dissolved gas in oil filled equipment.

IS:10028Code of practice for selection, installation and maintenance of transformers.

IS:12676Dimensions for OIP insulated condenser bushings.

CBIPManual on transformer.

Equipment complying with other internationally accepted standards will also be considered if these ensure performance and constructional features equivalent or superior to standards listed above. In such a case the Bidder shall clearly indicate the standards adopted, furnish a copy in English of the latest revision of standard alongwith copies of all official amendments and revisions in force as on date of opening of bid and clearly bring out the salient features for comparison.

3.0 CLIMATIC CONDITIONS:

The transformers are required to operate satisfactorily under the following site conditions:

3.1Max. temperature

50 C

3.2Min. temperature

-2.5 C

3.3Max. relative humidity

100%

3.4Min. relative humidity

26 %

3.5Average number of rainy days per annum

Nearly120 days

3.6Average annual rain fall

900mm

3.7Average number of dust storm days per annum.

35

3.8Isoceraunic level

45

3.9Max. Wind pressures

195 kg/sqmt.

3.10Altitude above mean sea level

Less than 1000 mt.4.0 TYPE AND RATING :

4.1The transformer shall be of two winding, 3 phase oil immersed core type with ONAN/ONAF cooling suitable for outdoor service as step down transformers. The transformer shall not be provided with the tertiary delta winding.

4.2The ratings and other characteristics which are not covered elsewhere shall be, as detailed in following clauses:4.2.1Max. Continuous capacity:a)ONAN

40 MVA

b)ONAF

50 MVA

4.2.2Number of phases

3

4.2.3Frequency

50 Hz

(5%)

4.2.4 Rated Voltage :

a)HV side

132kV

b)LV side

33kV

4.2.5Connections :

a) HV side

Star

b)LV side

Star

4.2.6Vector group

YYO

4.2.7%age Impedance

10% at

50 MVA base

4.2.8ON load taps on HV side +5% to -15% in steps of 1.25% each

4.2.9a)Insulation level

132 kV 33 kV

i)Lighting withstand

550 kV 170kV

ii) Power frequency

230 kV 70 kV

withstand voltage

(rms)

(rms)

b)Insulation level of Bushings

i)Lighting Impulse

650 kV 170kV

voltage

ii)Power frequency

275 kV 70 kV

voltage

(rms)

(rms)

4.2 10 Total Creepage Distance :

a) Total: 25mm per kV corresponding to highest system voltage i.e. 145 kV, 36 kV, 12 kV.

b) Protected: 50% of the total Creepage distance

5. GENERAL DESIGN OF TRANSFORMER: -5.1The transformer and accessories shall be so designed as to facilitate inspection, cleaning and repairs. The requirement of Indian Electricity Rules shall be kept in view.

5.2The design shall ensure satisfactory operation under severe working conditions due to fluctuating load of steel furnaces and voltage variations in the system including those, due to short circuits. The transformers shall be designed as to minimize the risk of accidental short circuits caused by animals, birds or vermins.

The design shall incorporate every reasonable precaution and provision for the safety of all those concerned in the operation and maintenance of the equipment keeping in the view the requirement of Indian Electricity Board.

5.3All material used shall be of the best quality and of class most suitable for working under specified conditions and shall withstand the atmospheric conditions and temperature variations without undue deterioration or distortion or setting up of undue stress in any part thereof.

5.4Cast iron shall not be used for any parts other than the radiator valve bodies.

5.5Corresponding parts liable to replace shall be interchangeable.

5.6All taper pins to be used in the mechanism shall be split types as per latest edition of IS: 2393.

5.7All mechanism should be rust and corrosion proof. Means shall be provided for lubrication of moving parts not immersed in oil.

5.8The construction shall be such as to avoid air or water pockets. Special care shall be exercised to reduce noise and vibration to the minimum level.

5.9Steel bolts of suitable finish will be used for diameters above 6mm. Brass bolts or studs used for electrical connections shall not be of less than 6mm dia. On outdoor equipment, all bolts, nuts & washers in contact with current carrying nonferrous parts shall be phosphor bronze:

5.10All nuts bolts and pins shall be locked except those which are external to the transformer. If bolts and nuts are so placed as to be inaccessible by means of ordinary spanners, suitable special spanners shall be provided by the supplier.

5.11Labels shall be provided for all apparatus like relays, switches, fuses, etc. housed in any cubicle or marshaling kiosks. These shall be of incorrodible material with matt/satin finish and permanent lettering. Labels mounted on black surface shall have white letters & danger notices shall have red lettering on a white background. The labels shall be secured by means of brass screws or rust protected steel screws.

5.12Surface in contact with oil shall not be galvanized or cadmium plated.

5.13Before painting, all ungalvanised parts shall be cleaned made free from rust, scale and grease and external rough surfaces smoothened filled with metal deposition. The interior of the tank and other oil filled chambers shall be cleaned by shot blasting or any other suitable method.

5.14All external surfaces shall be given three coats of paints except for nuts, bolts and washers which may be given one coat after erection. The final coat shall be a glossy oil and weather proof, nonfading paints of shade 631 of IS:5.

5.15The interior of mechanism chambers and kiosks shall be given 3 coats of paint, the final coat being of a light coloured anticondensation mixture.

5.16LOCKING OF OUTER RADIAL SPACERS :

The outer most radial spacers of the winding shall be locked in position by means of vertical strips so that the same can not fall off/got displaced.

5.17TIGHTENING OF THE NUTS OF THE COIL CLAMPING BOLTS :

The proper & complete tightening of the nuts of the coil clamping bolts must be ensured by the manufacturers. The tightening of the nuts to the designed value and that the nuts of all the coils clamping bolts are tightened to same extent, should be carried out with torque spanners.

The devices used for locking the nuts of coil clamping bolts must be of such a quality and such care should be taken first in tightening the nuts and next in locking them in position that the arrangement does not work loose due to vibrations caused by short circuits and fluctuating loads etc.

5.18The noise level shall not be more than 5db above NEMA standard publication TR1.

5.19The transformers shall be designed to have short circuit rating of two seconds as per ISS2026.

6.INSULATING OIL:-Sufficient insulating oil of Napthenic type (made from Naphthenic crude) in which paraffinic content should be less than 50% and aromatic content 4 to 12% conforming to BS: 148/IEC:296 class-1 shall be supplied for first filling of each transformer. Particular attention shall be paid to deliver the oil at site free from moisture and of uniform quality through out in non-returnable steels drums. The quantity of oil for first filling of each transformer shall be stated in tender along-with trade mark of the oil to be supplied. Use of inhibitors in oil shall not be resorted to. 10% extra oil of the total quantity of oil shall be supplied along with the transformer.

7.LIMIT OF TEMPERATURE RISE:-

7.1 With the above climatic conditions given in clause-3 each transformer shall be capable of operating continuously on any tap at their normal rating without exceeding the following temperature rises

(i) 50 deg C in oil by thermometer

(ii) 55 deg C in winding by resistance

(iii) Winding Gradient i.e the difference between average winding average oil temperature not to exceed 13 deg C.

(iv) Temperature of hot spot in windings not to exceed 98 deg C when calculated over max annual weighted average temperature of 32 deg C.

7.2 The limits of temperature rise mentioned above will have to be satisfied by the manufacturer by carrying out the heat run test at the lowest negative tap. This test shall be carried out by feeding 1.1 times the total losses at 75 deg C at highest current tap.7.3 OVERLOAD CAPACITY & CONTINOUS RATING

The safe overload capacity of the transformer and the duration of overload under maximum temperature conditions without any damage to the winding or harmful effects on the insulation shall be clearly stated in the tender which must be asper IEC-354/IS6600,guide for loading of oil immersed transformer.

8.0 IMPEDANCE

The transformer shall have 10% impedance on 50 MVA base respectively with tolerance as per IS:2026/Part-I(1983). Impedance shall include positive and zero sequence and shall be expressed in terms of the branches of star connected equivalent diagram, all on the same kVA base and range shall be given for each branch of the equivalent circuit in turn.

9.0 FREQUENCY:-The transformer shall be suitable for continuous operation with a 5% frequency variation from a normal of 50 HZ without exceeding the temperature rise as specified in clause-7.1 above.

10.0 FLUX DENSITY, CORE CONSTRUCTION and INSPECTION

10.1The transformer should be so designed that the working flux density should not exceed 1.57 Tesla at normal voltage, frequency.

10.2Tenders with higher flux density than specified limit shall not be considered.

10.3The core shall be built up with thin laminations of high grade. non-ageing, low loss, high permeability cold rolled super grain oriented silicon steel. Known as MOH High B Grade or superior grade CRGO steels of maximum 0.27 mm or low lamination thickness especially suitable for transformer core.

10.4(a) (i)Bidder should have in house core cutting facility for proper monitoring & control on quality and also to avoid any possibility of mixing of prime material with defective/second grade material. The purchaser may witness the core-cutting operation. In case the in house core cutting facility for core cutting is not available then the same shall be carried out in the presence of the representative of HVPN.

(ii)Inspection call notice for the purpose should be accompanied with the following documents as applicable as a proof toward use of Prime core materials :-

a)Invoice of supplier.

b)Mills test certificates.

c)Packing list.

d)Bill of loading.

e)Bill of entry certificates by customs.

Core material shall be directly procured either from the manufacturer or through their accredited marketing organisation of repute and not through any agent.

10.4(b) After being sheared, the laminations shall be treated to remove all burrs. They shall be coated with a baked enamel insulation coating. The insulation shall be inert to the action of hot transformer oil and shall be perfectly adhesive. Paper and varnish insulation shall not be accepted. Particulars of proposed insulation shall be stated in the tender. Laminations shall be checked for burrs during stage inspection.

10.5 The core shall be rigidly clamped and/or bolted to ensure adequate mechanical strength and to prevent vibrations during operation. The bolts used in the assembly of the core shall be suitably insulated and the clamping structure shall be constructed that the eddy currents will be minimum.

10.6Construction of the core shall be such that number of steps in the limb and yoke shall be matching and dimensionally identical to minimize the effect of cross fluxing and better mechanical strength.

10.7The core shall be provided with Lugs suitable for lifting the complete core and coil assembly of transformer. The Core & coil shall be fixed in the tank such that its shifting will not occur when the transformer in moved or when a short circuit occurs.

10.8The design of magnetic circuit shall be such as to avoid static discharge development of short circuit paths within itself or to the earthing clamping structure and the production of flux components at right angles to the plane of the lamination which may cause local heating.10.9Every care shall be exercised in the selection treatment and handling of core steel to ensure that the laminations are flat and that finally assembled core is free from distortions.

10.10The supporting frame work of the core shall be so designed as to avoid the presence of pockets which would prevent complete emptying of the tank through the drain valve or cause trapping of air during filling.

10.11Oil ducts where necessary should be formed across the plane of the lamination and be given a suitable slope to assist oil circulation. The overall design of core and winding should be such that free flow of oil is not obstructed.

10.12The frame work and clamping arrangement shall be earthed by connecting to the tank body through a copper strip. Yoke bolt area should be compensated if bolts are used for fastening of the core.

10.13The insulation of core to bolts and core to clamp plates shall be able to withstand a voltage of 2 KV RMS for one minute.

10.14Core and windings shall be capable of withstanding shocks during transport, installation, service and adequate provision shall be made to prevent movement of core and winding relative to tank during these conditions.

10.15All steel sections used for supporting the core shall be thoroughly sand blasted after cutting drilling and welding.

10.16CRGO used shall be strictly as per approved vendor as below:-

a) Nippon Steel Corp.Japan

b) Kawasaki Corp. Ltd.,Japan

10.17The tenderers should indicate the maximum flux density allowable continuously as well as for time intervals of 1 minute and 5 secs. and the limit of flux density at which core material used by them saturates.

10.18The name of the core material must be mentioned in the tender. The successful tenderer shall be required to furnish magnetization curves of the core material/design calculations and such other data/documents deemed fit by the Purchaser for being satisfied that flux density is as desired.

10.19Purchaser shall inspect the built-up core for verification of flux density for which all facilities shall be provided. The purchaser shall inspect/test the core material for various tests as per relevant IEC/IS to ensure quality. Core may also be inspected during horizontal assembly, built-up assembly.

Notes :

i)The above flux density has been specified to meet with the over fluxing of the core due to temporary over voltage of the order of 31% for l min, 44%for 5 sec. that may appear abnormal conditions such as those following sudden loss of large loads.

ii)Yoke bolt area and flitch plate areas shall not be counted in the net core area if these are provided for fastening core.iii) The design of limb and yoke shall be so co-ordinate that there is no cross fluxing at the joints.iv) The tenderer shall ensure that the CRGO supplier should have BIS certification. 11.SUPPRESSION OF HARMONICS:

The transformer shall be so designed as to suppress the harmonics voltage specially the 3rd & 5th, to eliminate wave form distortion and interference with communication circuits due to high frequency disturbances. Limiting percentage of harmonics at normal voltage and at maximum system voltage shall be stated in the tender.

12. WINDINGS:-12.1The 132kV windings shall have graded insulation whereas all other windings shall be fully insulated and the neutral points shall be insulated as amended in IS:2026.

12.2The transformers shall be capable of operation without danger on any particular tapping at the rated kVA when the voltage may vary by 10% of the voltage corresponding to the tapping.

12.3The windings and connections, insulation material shall not soften, ooze out, shrink or collapse during service.

12.4 No strip conductor wound on edge shall have a width exceeding six times its thickness. The conductors shall be transposed at sufficient intervals to minimize eddy currents and equalize the current and temperature distribution along the windings.

12.5The windings and connections shall be properly brazed to withstand shocks during transportation or transient conditions during service.

12.6The adequate preshrinkage of the coil assembly using precompressed press board material having low moisture content for the radial spacer blocks shall be ensured by the manufacturers so that there is no displacement of the radial spacer blocks due to frequent short circuits on the transformers.

12.7All windings after being wound and all fibrous hygroscopic materials used in the construction of the transformer shall be dried under vacuum and impregnated with hot oil.

In addition to this the drying process be sufficiently extended for proper stabilization of the coil assembly. More than one cycle of soaking in oil followed by retightening of the coil assembly should be adopted.

12.8The coil clamping rings wherever used, shall preferably be of flat insulated steel laminations. Auxiliary laminated material except bakelised paper shall not be used.

12.9The clamping arrangement shall exert equal pressure on all columns of spacers of the transformer windings built of sections or disccoils separated by spacers. In no case, spiral winding will be used either for HV or LV windings.

12.10The radial spacer blocks must be made of precompressed pressboard material, which will not soften while in contact with oil or fray out into fibers or edges. The slots should be so dimensioned that the blocks will not come out of the slots.

Uniform distribution of coil clamping force shall be designed by using an adequately large number of coil clamping bolts and by transferring the clamping force from clamping bolts to the clamping plates through intermediate members which can spread the clamping force over a large area.

12.11All joints shall be brazed/crimped considering the vibrations due to short circuits and load fluctuations.13.CURRENT DENSITY:

The purchaser shall be at liberty to inspect built-up winding for its quality, weight of copper, insulation and overall weight of coil assembly. The size of conductor used for different windings shall also be checked during stage inspection to check the current density. The transformer shall be so designed that the current density of all the windings and the regulating winding at the lowest tap should not exceed 250 A/cm.Sq.

14. TANK CONSTRUCTION:-14.1.1The tank shall be fabricated of a suitable grade steel and strong enough to allow the lifting of complete transformer with oil by means of a crane or jacks and transported to site without overstraining the joints etc.

14.1.2The main tank body shall be capable of withstanding a vacuum of 100.64 KN/m2 (760mm of Hg.)

14.1.3 The base shall be so designed as to allow the transformer to be moved by skidding without any injury.

14.1.4 All channeled constructions and stiffeners shall be designed to avoid retention of water.

14.1.5The tank construction shall be free of air pockets, where such pockets cannot be avoided vent pipes of 15 mm internal dia shall be provided to vent gases into the main expansion pipes. In case of short branch pipes, however, minimum diameter may be taken as 6mm.

14.1.6 All joints other than those, which may have to be broken, shall be welded. When required they shall be double welded. All bolted joints to the tank shall be fitted with suitable oil tight gaskets, which shall give satisfactory service under the operating conditions and guaranteed temperature rise conditions. Special attention shall be given to the methods of making hot oil tight joints between the tank and the cover and also, between the cover and the bushings and all other out-lets to ensure that the joints can be remade satisfactorily at site and with ease by semi-skilled labour.

14.1.7Suitable lifting lugs for lifting the transformer filled with oil shall be provided on the tank.

14.1.8Four jacking lugs shall be provided to enable the transformer complete with oil to be lifted or lowered by means of jacks. The lugs shall be fitted at a minimum height (excluding under base if detachable) of 300mm for transformer upto 10 tonnes weight and of 500mm for transformer above 10 tonnes weights.

14.1.9The transformer shall be provided with detachable steel flanged wheels of 250mm dia and suitable for moving transformer complete with oil. These shall be bi-directional and mounted on swivels which may be turned through 90o when the tank is jacked up and capable of being locked in position parallel to and at right angles to the longitudinal axis. The wheel be suitable for standard gauge track of 1676mm.

14.2TANK COVER

14.2.1 The tank cover shall be of bolted type and of adequate strength so as not to distort, when lifted. Suitable inspection cover shall be provided with lifting arrangements to give access to bushings, winding connections or testing the earth connections. The weight of each inspection cover shall not exceed 25 Kg.

14.2.2 Pockets shall be provided in the position of Max. oil temperature at CMR for fitting a thermometer and for bolts of oil and winding temperature indicators. The thermometer pockets shall be fitted with a captive screwed cap to prevent ingress of water.

14.2.3 Suitable No. of jacking bolts shall be provided on tank cover, inspection covers/windows including OLTC.

14.3CONSERVATOR TANK, OIL GAUGE AND BREATHER

14.3.1 An adequate conservator tank of air cell type complete with sump and drain valves shall be provided in such a position as not to obstruct the electrical connections to the transformer.

14.3.2 If the sump is formed by extending the feed pipe inside the conservator, this extension shall be atleast 25mm.

14.3.3 One end of the conservator shall be bolted type to facilitate cleaning.

14.3.4 The conservator shall be provided with a magnetic oil level gauge.

14.3.5 The oil connections from the transformer tank to the conservator shall be at rising angle of 3 to 9 degrees to the horizontal upto Buchholz relay. The inside diameter of the pipe shall be 80mm. The Buchholz relay will have suitable valves on its both side so as to facilitate its testing at site as well as cut off oil supply to the transformer.

14.3.6 The conservator shall be provided with oil preservation system, which should be suitable either to remove moisture continuously from air entering the air space with which they are connected or may not allow direct contact of atmospheric air with oil during operation, in addition to silicagelbreather.

14.4VALVES:

14.4.1The transformers shall be provided with 2 No. filter valve each of 50 mm size one mounted close to the top of the main tank & the other close to bottom of the tank oil circulation and one drain valve of 80mm size with plug. The conservator shall have drain plug of 25mm size.

14.4.2Two robust sampling valves with spouts suitable for taking samples of top, and bottom oil. The top sampling valves shall be brought down by internal pipe connections. Suitable name plates shall be affixed to the sampling valves. The sampling device shall not be fitted on the filter valve.

14.4.3 Two air release plug of 15mm shall be provided.

14.4.4 Plugs shall be supplied for all valves opening to atmosphere.

14.4.5 All valves shall be of gun metal and comply with the latest edition of IS: 3639.

14.5PRESSURE RELIEF DEVICES:

A suitable pressure relief device of 6" diameter shall be provided on the main tank and of 3" diameter shall be provided on OLTC for rapid release of any pressure in transformer, which may endanger the equipment. The device (s) shall operate at static pressure less than hydraulic test pressure for transformer tank of OLTC chamber. If the device is mounted on tank cover, it shall be fitted with a skirt projecting 25mm inside the tank and of such construction as to avoid gas accumulation.

In addition to pressure relief device(s) the provision of explosion vent should also be made and the diaphragm shall be situated above max. oil level or second PRD on the opposite side of the first PRD be provided.

14.6EARTHING TERMINALS:

14.6.1 Two earthing pads suitable for connecting 50x8mm mild steel flat shall be provided at positions close to the two diagonally opposite bottom corners of tank. These grounding terminals shall be suitable for bolted connection. Two earthing terminals shall also be provided each on marshalling box and any other equipment mounted separately.

14.7JOINTS AND GASKETS: -

14.7.1All gaskets used for making oil tight joints shall be of granulated cork bonded with synthetic rubber. Metal tops shall be provided for preventing over compression wherever compressible gaskets are provided.

14.8RATING AND DIAGRAM PLATES:

14.8.1Each transformer shall carry a diagram plate showing internal connections, voltage vector relationship of different windings, plan view of the transformer showing physical relationship of the terminals and no load voltage and corresponding current for each tap.

14.8.2 Each transformer shall be provided with a rating plate data as specified in IS: 2026.

14.8.3 I.R. values alongwith oil temperature at the time of testing at manufacturer's works shall be indicated on rating plate or separate plate, to be provided on transformer.

14.9 THERMOSYPHON FILTER ARRANGEMENT

Thermosyphon filter arrangement shall be provided on the transformer for preserving the quality of Transformer Oil. The filter assembly shall be mounted on the Transformer as well as ground supported and connected with pipes and shut off valves. Suitable instructions required to be followed for commissioning, dismantlement & maintenance of the filter arrangement, re-generation and storage of the adsorbent etc. must be included in the instruction manual. A detailed drawing showing internal arrangement, shall also be required to be submitted. Suitable capacity pump (alongwith motor) shall also be provided to boost circulation of oil. The pump and motor should not be in main pipe line. It should be in bypass pipe line having suitable valve to isolate from main pipe line. The main pipe line should have two shut off valves at the bottom.

NOTE: -The pump and motor should be weather proof(Flow well Type).

The oil & sorbent capacity required in the Thermosyphon Filter is as under: -

(i)Quantity of oil

2.0% of total oil by weight.

(ii)Quantity of adsorbent

1.25% of total oil by weight.

15. COOLING PLANT:-15.1Detachable radiators shall be fitted on the main tank with machined flanged outlet and inlet. Each radiator shall be provided with 19mm drain plug at Bottom and 19mm air release plug at the top. Valves shall be provided on the tank at each point of connection to radiators.

15.2In case separate cooler banks are used, they shall be suitable for mounting on a flat concrete base. These shall be provided with a valve (25 mm) at each point of connection to the transformer tank, removable blanking plates to blank off main oil connections to each cooler. 25 mm drain valve. Thermometer pockets with captive screwed cap at inlet and outlet of each separate cooler, filter valve at top and bottom and air release plug of 15mm.

15.3The motor blowers shall be direct driven suitable for continuous out door operation and complete with necessary air dusting. These shall be mounted independently from the radiator and in the case, these are radiator mounting type, use shall be made of some antivibration means. Care shall be taken that the blower unit is capable of being removed without disturbing the radiator structure. The blades shall be suitably painted and shall not be of hollow sections. Suitably painted wire mesh guards with mesh not greater than 25mm shall be provided to prevent accidental contact with the blades.

15.4MOTORS:-

15.4.1 The motor shall be squirrel cage totally enclosed weather proof type suitable for direct starting and for continuous running from 415240 volts, three phase/single phase 50 C/S supply. The motors shall comply with IS as applicable for continuous rated machine.

15.4.2 All motors shall be capable of continuous operation at frequency 50Hz with variation of 5 % and 415/240 V AC 10 % variation of the normal voltage without injurious over heating.

15.4.3 All motors shall have ball or roller bearing with hexagonal nipples for greasing. In case of vertical spindle, motor shall have bearing capable of withstanding thrust, due to weight of the moving parts.

15.4.4 Varnished cambric or glass insulator shall be used for connections from stator winding to the terminal suitable for external wiring. The motor terminals shall be of stud type and totally enclosed.

15.5COOLER CONTROL:-

15.5.1 Each motor or group of motors shall be provided with a 3 pole electrically operated contactor with control gear for motor operation by hand and automatically through winding temperature indicator. Provision shall be made for over load protection but no volt release shall not be provided.

15.5.2 All connection shall be so arranged as to allow either individual or collective operation of the motors, Alarm indication (audio and visual) for failure of fans and to indicate failure of power supply shall be provided.

15.5.3 The control equipment shall be installed in the marshaling box as specified in Cl.20 in readily accessible position.

15.5.4 The alarm indication for failure of power supply and failure of individual fans be provided through independent non trip alarm scheme conforming to the following:

i)The closing of an initiating contact shall actuate a buzzer and will be accompanied by a flag indication on the concerned auxiliary relay.

ii)The closing of an initiating contact shall glow a lamp, which will not reset until the fault has cleared.

iii)It shall be possible to silence the buzzer by pressing 'Accept' push button. If after canceling the alarm but before resetting the visual signal, the same fault persists the buzzer shall be suppressed.

iv)If after canceling the alarm but before resetting the visual signal, some other fault takes place, the alarm accompanied by flag indication on appropriate auxiliary relay shall taken place.

v)If after canceling the alarm and after resetting the visual signal, the same fault appears or some other fault take place, the alarm, flag indication and nontrip lamp indication shall reappear as usual.

vi)The nontrip alarm acceptance shall be by means of push button and resetting of visual signal may also preferably be done through a push button.

vii)Means shall be provided for test checking the lamp and alarm circuit at frequent intervals.

viii) The equipment shall be suitable for 220 Volts DC operation.

Static facia aunnuciator conforming to the foregoing requirements of non trip alarm scheme too would be acceptable.

16. VOLTAGE CONTROL (ON LOAD TYPE):-16.1The transformer shall be provided with voltage control equipment of the tap changing type for varying its effective transformation ratio while the T/Fs are on load and without producing phase displacement.

16.2Equipment for 'local' and 'remote' electrical and 'local' manual operation shall be provided and shall comply with the following conditions. Local/ remote switch may be housed in remote control panel or in tap changer drive mechanism.

16.2.1It shall not be possible to operate the electric drive when the manual operating gear is in use.

16.2.2It shall not be possible for any two electric controls to be in operation at the same time.

16.2.3The equipment suitable for supervisory control and indication on a multi way switch, makebefore break, having one fixed contact for each tap position, shall be provided and wired to the tap changer drive gear. This switch shall be provided in addition to any, which may be required for remote tap change position indication purpose. Supervisory indication shall also be provided in the form of contacts to close on. "Tap change incomplete" condition. All other components of the supervisory gear if required be specified separately.

16.2.4Operation from the local or remote control switch shall cause one tap movement only. The control switch shall be returned to the 'neutral' position between successive operations.

16.2.5All Electrical control switch on the local operation gear shall be clearly labeled in a suitable manner to indicate the direction of tap changing.

16.3 The equipment shall be so arranged as to ensure that when a tap change has commenced, it shall be completed independent of the operation of the control relays or switches. In case of failure of the auxiliary supply while tap change is in progress or any other contingency such as stuck tap changer, adequate means shall be provided to safe guard the transformers and its auxiliary equipment.

16.4Suitable apparatus shall be provided for each transformer to give indications as follows: -

16.4.1To give indication, mechanically at the transformer and electrically at the remote control cubicle of the position of tap in use.

16.4.2To give an indication at the remote control cubicle that a tap change is in-progress, by means of an illuminated lamp.

16.5For remote control, the switches, tap position indicator, etc. shall be supplied duly mounted on remote control cubicle.

16.6All relays and operating devices shall be operated correctly at any voltage between the limits specified in the relevant ISS.

16.7The tap changing mechanism and mechanism shall be mounted in the oil tank or compartment mounted in an accessible position on the transformer.

16.8Any non oil filled enclosed compartment shall be adequately ventilated, Thermostatically controlled heaters shall be provided in the driving mechanism chamber and in the marshaling box. All contactor & auxiliary relay coils or other parts shall be suitably protected against corrosion or deterioration due to condensation, fungi etc.

16.9The tap changer contacts which are not used for making or breaking current like separate selector switch contacts can be located inside main transformer tank where tap changer construction permits such an arrangement. The oil in case of on load tap changer having separate compartment for selector contacts shall be maintained under conservator head by means of pipe connection from the highest point of the chamber to the conservator. Such connection shall be controlled by suitable valve and shall be arranged so that any gas leaving the chamber will pass into the gas and oil actuated relay. A separate buchholz relay may be provided for this compartment.

16.10It shall not be possible for the oil in these compartments of the tap change equipment which contain contacts used for making or breaking current, to mix with the oil in the compartments containing contacts and not used for making or breaking current.

16.11Any 'DROP DOWN' tanks associated with the tap changing apparatus shall be fitted with guide rods to control the movement during lifting or lowering operations. The guide rods shall be so designed as to take support of the associated tank when in the fully lowered position with oil. Lifting gear fitted to 'Drop Down' tanks shall include suitable device to prevent runaway during lifting and lowering operations. They shall be provided with adequate breathing arrangement. The tap changer shall be mounted in such a way that the cover of the transformer can be lifted without removing connections between windings and tap changer.

16.12Each compartment in which the oil is not maintained under conservator head shall be provided with a suitable direct reading oil gauge.

16.13The alternating supply for electrical operation of the control and indicating gear shall be standard 415 Volts, threephase, 3 wire, 50 Hz. alongwith 240 Volts single phase, 2 wire 50 Hz, subject to a variation of 5 percent so that the equipment offered can withstand variation in AC

16.14Limit switches shall be provided to prevent over-running of the mechanism and except where modified in clause 18.15 shall be directly connected in the circuit of the operating motor. In addition a mechanical stopper or other approved device shall be provided to prevent overrunning of the mechanism under any condition.

16.15Limit switches may be connected in the control circuit of the operating motor provided that a mechanical declutching mechanism is incorporated.

16.16Thermal devices or other means like motor circuit breakers with shunt trip coil shall be provided to protect the motor and control circuits. All relays, switches fuses, etc. shall be mounted in the marshaling box or driving gear housing. These shall be clearly marked for purpose of identification. They shall withstand the vibration associated with tap changer gear operation.

16.17The control circuits shall operate at 110V single phase to be supplied from a transformer having a ratio of 415 or 240/55055 V with the center point earthed through a removable link mounted in tap changer drive.

16.18The whole of the apparatus shall be of robust design and capable of giving satisfactory service under conditions to be met in service including frequent operation.

16.19A fivedigit counter shall be fitted to the tap changing mechanism to indicate the number of operations completed by the equipment.

16.20A permanently legible lubrication chart shall be fitted within the driving mechanism chamber, where applicable.

16.21The indigenous make OLTC suitable for 132 KV voltage class insulation (graded) but the voltage class insulation should not be less than 66 KV and current rating as 300 Amp. The OLTC should be type tested from CPRI or other Govt. test house or from reputed Lab. Abroad to the extent the facilities of type test are available with CPRI.

17. PARALLEL OPERATION :-17. 1In addition to individual control of tap changer, provision shall be made to enable parallel operation of the tap changer when one unit is running in parallel with another similar unit of same rating.

17.2Suitable selector switch and controls shall be provided so that any transformer of the group can at a time be selected as master, follower or independent. Arrangement shall be made that only one of the transformers can be selected as master at a time.

17.3An out of step device shall be provided for each transformer indicating out of step condition by an indicating lamp and buzzer. It shall be arranged to prevent further tap changing when transformers in a group operating in parallel control are one tap out of step.

18. BUSHING INSULATORS AND TERMINALS:

18.1 Transformer shall be fitted with bushing insulators as follows: -

HV bushing: 145 kV class, condenser bushing of 800 Amp. rating with arcing horns.

L.V. Bushing: 36 kV class, oil communicating type porcelain bushing of 1000 Amp. rating but with suitable arcing horns.

L.V.-N Bushing: 36 kV class, oil communicating type porcelain bushing of 1000 Amp. rating but without arcing horns.

H.V-N Bushing: 36 kV class, oil communicating type porcelain bushing of 630 Amp. rating but without arcing horns.

The characteristics of the bushings shall be in accordance with IS: 2099 and IS: 3347.

The bushing insulators except for neutral bushing shall be provided with adjustable arcing horns and the bidder shall furnish calibration gap to decide actual gap setting.

A continuous flexible pull through lead suitably sweated to the end of winding copper shall be connected to the connector in the helmet of the 220/132 kV Bushing. The bushings may be filled with oil, which may not be in communication with the oil in transformer. All porcelain shall be free from defects and thoroughly vitrified with a smooth, hard and uniform brown glaze. It should be capable of satisfactory use under the climatic conditions as specified in clause-3.0.

In case of paper insulation care shall be taken to prevent ingress of moisture and a final coat of nonhygroscopic varnish shall be given to them.

All clamps and fittings made of malleable iron or steel shall be galvanized as per IS: 2629. The bushings flanges shall not be of reentrant shape which may trap air.

Bimetallic terminal connectors shall be supplied suitable for single 0.4 Sq. inch ACSR Zebra conductor for HV, LVN & HVN and twin ACSR Zebra conductor for LV side . The take off for H.V. & L.V. connectors will be Vertical and for Neutral it should be suitable for horizontal take off.

The connectors shall have six number bolts provided with check nuts & washers. The connectors shall have rating corresponding to those of equipment or higher and shall be designed most liberally with a higher factor of safety to comply in all respects with temperatures rise, resistance, tensile strength shortcircuit withstand capability tests as specified in IS: 55611970 or amendment thereof (Latest edition). Aluminum alloy used in the manufacture of Bi-metallic connectors shall conform to designation Grade 4600 of IS: 6171975. The steel bolts, nuts washers and check nuts shall be hot dip galvanized marked with ISI certification mark or of GKWmake.

19.TEMPERATURE INDICATING DEVICES:

19.1All transformers shall be provided with a dial type thermometer for indicating oil temperature. The indicator shall be fitted with a pointer to register maximum temp recorded and adjustable set of mercury contact for alarm and trip.

19.2In addition, all the transformers shall be provided with a dial type Hot Spot winding temperature indicator in HV & LV winding. The indicator shall have a pointer to register maximum temperature reached and four sets of adjustable mercury contacts for alarm, trip, automatic control of fans & remote indication. The static remote repeater (for winding temperature indicator) suitable for flush mounting shall be installed on remote tap charge control cubicle.

19.3The temperature indicators shall be housed in marshaling box.

19.4The alarm (mercury) contact of WTI & OTI shall be adjustable between 50oC to 100oC where as their trip (mercury) contacts shall be adjustable between 60oC and 120oC. The temperature difference between opening & closing of these mercury contacts shall not be more than 10oC.

19.5The mercury contacts used for controlling cooling plant motors shall be adjustable to close between 50oC and 100oC. The temperature differential between opening & closing of this mercury contract shall be between 10oC to 15oC.

19.6All contacts should be accessible on removal of the cover adjustable to scale. It shall also be possible to move the pointers by hand for checking the operation of contacts and associated equipment.

19.7In addition each transformer shall be provided with a dial type thermometer for indicating the ambient temperature.

20.GAS AND OIL ACTUATED RELAYS: -

20.1The transformer shall be provided with a gas and oil actuated relay fitted with alarm and trip contacts for main tank & oil surge relay for its OLTC as per IS:3637.

20.2Each such relay shall be provided with a test cock to take a flexible connection for checking relay operation

20.3A machined surface shall be provided on top of relay for checking mounting angles in the pipe cross level of relay and its setting.

20.4 The pipe work shall be such as to allow any gas formed in the tank to pass through the relay. The oil circuit through the relay shall not form a parallel delivery path with any circulating oil pipe, nor shall it be tied into or connected through the pressure relief vent.

20.5 Adequate clearance between oil pipe work and live metal parts shall be provided.

21.MARSHALING BOX:

21.1A sheet steel (of 10 SWG size) vermin proof well ventilated and weather proof marshaling box of suitable construction shall be provided for the transformer auxiliary apparatus. The box shall have domed or sloping roofs. Ventilation louvers, suitably padded with felt, shall also be provided. It shall be painted as per Cl.5.14.

21.2The marshaling box shall accommodate temperature indicators. Local electrical control of tap changer (if same cannot be housed in motor drive housing.), Control & protection equipment for cooling plant, terminal boards and gland plates for cable etc. The equipment shall be mounted on panels and panels wiring shall be done at the back for interconnections.

21.3The temperature indicators shall be mounted at about 1600mm from ground level.

21.4A metal clad heater with thermostat, controlled by a waterproof rotary switch on the outside of the box, shall be provided.

21.5The incoming cables shall enter from the bottom with gland plate not less than 450mm from the base of the box. Care shall be taken to avoid ingress of water from the cable trench.

22. CONTROL CONNECTIONS, INSTRUMENTS WIRING, TERMINAL BOARD AND FUSES: -

22.1All cables and wiring shall be suitable for use under the conditions as specified in Section -I. Any wiring liable to come in contact with oil shall be of oil resisting insulation. The bare ends of stranded wire shall be sweated together to prevent oil from creeping along the wire.

22.2The instrument and panel wiring shall be run in PVC or non rusting metal cleats of limited compression type.

22.3The box wiring shall be as per relevant ISS. All wiring shall be of stranded copper of 660V grade and size not less than 4 Sq. mm. for CT leads and not less than 2.5 Sq. mm for other connections. The panel wires and multi core cable shall bear ferrules of white insulation material with indelible marking in black and as per relevant ISS. Same ferrule number shall not be used on wires in different circuits. Double ferrule may be provided where a change in number is required.

22.4Stranded wires shall be terminated with tinned Ross Courtney terminals, washers or crimped tubular lugs. Separate washers shall be used for each wire. Wire shall not be jointed/tied between terminal points.

22.5Where apparatus is mounted on panels all metal cases shall be separately earthed by copper wire or strip not less than 2.5 sq. mm. The screens of screened pairs of multi core cables shall be earthed at one end of the cable only.

22.6All terminal boards shall be of stud-type & mounted obliquely towards the rear door and these boards shall be spaced not less than 100mm apart. Suitable insulation barriers shall be provided between adjacent connections. No live metal shall be exposed at the back of terminal boards.

22.7All fuses shall be of cartridge type and fuses and links shall be properly labeled.

23.EQUALIZATION FORMULA:

The losses at principal tap of each transformer shall be stated in the tender ONAF rating at full load at 750C.

For the purpose of arriving at comparable prices, the iron, copper and auxiliary losses shall be capitalised as per capitalization formula given below:

=3,86,700( Wi + 0.45 Wc + 0.45 Wp)

Where

Wi

=Iron (No load) Losses

Wc

=Copper (Load Losses)

Wp

=Auxiliary Losses

The maximum sealing of component and weightage average losses shall be as per clause 24.0 and no positive tolerance shall be allowed on these valuesIn case losses of the T/F are found to be higher then the specified values at any stage within three years from the date of commissioning the capaitalized value of excess losses, as compare to the specified value shall be recovered as per following capitalization formula:-Amount recoverable (Rs.)= 3,86,700 (Wi + 0.45 Wc + 0.45Wp). 24.Losses:-

The losses of each transformer shall be stated in the tender for OFAF at principal tap rating (at full load at 75 deg. C) which shall be less than:-

Sr. No.Type of Losses40/50 MVA, 132/33 KV T/F

1No Load Losses30 KW (Max)

2Load Losses200 KW (Max)

3Auxiliary Losses4.0KW (Max.)

4overall average wt. losses (based on capitalisation formula of Wi+0.45 (Wp+Wc) 110KW (Max.)

24.1 Noise level

:80 dB

Transformer offers shall be rejected if audible sound level is higher than max.80 dB.

25. TESTS:

25.1ROUTINE TESTS:

All routine test shall be carried out on each transformer as per IS-2026/ IEC-76. In the presence of purchasers representative.

25.2TYPE TEST

Following type test shall be carried out on one transformer as per ISS 2026 in the presence of purchasers representative.

(i) Temperature rise test (along with DGA).

(ii) Impulse voltage withstand test as per clause 13 of ISS-2026 /1981 Part-III on one limb.

25.3In addition, the following tests shall be carried out on the Transformer Tank:

25.3.1OIL LEAKAGE TEST:

All tanks and oil filled compartments shall be tested for oil tightness by being completely filled with oil of viscosity not greater than that of insulating oil to IS: 335 at ambient temperature and subjected to a pressure equal to normal pressure plus 35KN/M2 (5 lbs sq. inch) measured at the base of the tank. This pressure shall be maintained for a period not less than 12 hours, during which period no leakage shall occur.

25.3.2Following tests shall be carried out on each transformer as reference test

i.Measurement of tan delta and capacitor of T/F Winding and bushings at 5kV & 10 kV.

ii.Magnetic balance test.

iii.Magnetising current at low voltage

iv.Measurement of percentage impedance at all taps at low voltage.

25.3.3TRANSFORMER OIL:

Sufficient quantity (along with 10% extra) of insulating oil of napthenic type (as per Clause-6 of specification) conforming to BS:148/IEC-296 Class-1 shall be put up for inspection, at least 3 weeks before putting up the transformer for testing/inspection, at sub-supplier works as per IS:335/BS/IEC. One sample of the oil shall also be got tested from CPRI or any other Govt. approved testing house. The inspected oil shall be dispatched to site as per dispatch instructions of purchaser.

25.3.4 SHORT CIRCUIT TEST

Short circuit test in accordance with clause 16 of ISS-2026 or latest edition shall be got conducted on one of the units at any test Agencies where facilities exist in the presence of Purchaser's representative .However, in case of those manufacturers who have already got short circuit test in accordance with Cl. 16 of ISS-2026 or latest edition conducted during the last 5 years on same design and capacity of the Transformer, fresh short circuit test is not required to be conducted. The bidder in such a case shall submit the copy of type test report along with the bid. If this test is not conducted by the firm earlier, then charges for this test shall be borne by the bidder.

The warranty in case of Power Transformer shall be 18 months from the date of commissioning or 24 months from the date of receipt whichever is earlier. All other stipulations of Warranty Clause as per Schedule-D of purchase regulation shall remain same.

25.4The purchaser reserves the right to have any other, reasonable test carried out at his expense either before shipment or at site to ensure that the transformer complies with the requirement of this specification.

25.5STAGE INSPECTION:

Stage inspection of built up core (in horizontal/vertical position), windings, tank and radiators shall be carried-out as detailed below:-

a. CORE:

i) Measurement of flux Density.

ii) No Load Loss Measurement by providing dummy oils.

iii) Tests of CRGO sample taken from the core shall be carried-out for Carlite test (Resistance Measurement), Watt Loss Test, Lamination Thickness & Aging Tests.

iv) Physical inspection for quality of workmanship.

v) Slitting/Cutting of core.

b. WINDINGS:

i.Measurement of cross-sectional area for current density.

ii.Measurement of weight of bare copper/ cover by resistance methods.

iii. The purity test of copper shall be got conducted on sample of copper for assessing its quality, from two independent NABL accredited laboratories. c. TANK:

i)Vacuum Test:

One transformer tank out of the lot shall be subjected to vacuum pressure of 100.64 kN (760 mm of hg). The tanks to be designed for full vacuum shall be tested at an internal pressure of 3.33 KN/M2 (25mm of Hg.) for one hour.

The permanent deflection of flat plates after the vacuum has been released shall not exceed the values given below without affecting the performance of the Transformer.--------------------------------------------------Horizontal length of flat plate (mm). Permanent deflection (mm).

-----------------------------------------------------

Upto & including 750

5.0

7511250

6.5

12511750

8.0

17512000

9.5

20012250

11.0

22512500

12.5

25013000

16.0

above 3000

19.0

-------------------------------------------------------

ii)PRESSURE TEST:

One transformer out of the lot shall be subject to the pressure corresponding to twice the normal head of oil or normal pressure plus 35KN/M2 (which ever is lower) measured at the base of the tank and maintained for one hour. The permanent deflection of flat plates after removal of excess pressure shall not exceed the figures specified as above.

d.RADIATORS:

Radiator shall be routine and type tested at sub suppliers' work as per relevant standard. Test reports are required to be supplied at the time of final inspection.

NOTE: a.The insulation resistance values of the transformer windings will be recorded at the time of carrying out routine tests, for 20 seconds, one minute, two minutes with the help of 5000V motorized meggar. (Preferably EVERSHED/ AVO & VIGNOLE MAKE). The polarisation index values (ratio of 120/20 sec. value) will be accordingly calculated and recorded in the test certificates and it should not be less than 1.5.

b.Dissolved gas analysis test shall be got carried-out before and after heat run test at CPRI.

c.Capacitance and Tan Delta values for each transformer and condenser bushings will be taken and recorded in the test certificates at 5 kV & 10 kV. Insulation resistance value of condenser bushings shall also be recorded.

d.Lightening impulse test with the chopped wave applications as per clause 13 of IS: 2026/ 1981 (Part-III) amended upto date. This test will be carried out on one of the limbs of HV and LV winding with positive polarity.

e.The tender should clearly indicate the testing facilities available with them and tests which are to be arranged outside.

Supplier shall submit in house test certificates at least 15 days in advance for final testing of T/F. For testing T/F, all measuring instruments shall be of highest efficiency and best quality. These shall be got calibrated from NPL/ Govt. Agency and be got sealed by calibrating agency. HVPN reserves the right to calibrate the instruments in the manner it desires.

Losses shall be measured with 3-wattmeter method only. Resistance shall be taken with Double-Kelvin Bridge. Losses can be measured directly from CTs and PTs and not through the panel. Ratio of the measuring instrument shall be such that the multiplying factor is the minimum.

All tests shall be carried out in the presence of the Purchaser before dispatching the material. Test certificates in quadruplicate will be submitted to the Purchaser for approval. No material shall be despatched without prior inspection and approval of test certificates unless otherwise agreed to. Type and routine test certificates of all bought out items from recognised testing agency shall be submitted for approval before commencing supplies. OLTC scheme including the master follower functioning shall also be checked. Only fully assembled transformer including mounting of radiators shall be put-up for inspection.

26. DRAWINGS:

26.1The following drawings shall be supplied as part of the tender.

26.1.1 Outline dimensional drawing of transformer and accessories.26.1.2.1 Bushing and terminal connectors drawing.

26.2The successful bidder shall submit final version of drawings complete in all respects as detailed in the following sub-clauses, in quadruplicate, within four weeks of placement of order for purchasers approval. The purchaser shall communicate his comments/approval on the drawings to the supplier within four weeks of their receipt. The manufacturer shall, if necessary, modify the drawings and resubmit the same for purchasers approval within two weeks of receipt of comments. Such duly revised drawings will be approved by the purchaser within two weeks of the receipt. After receipt of purchasers approval to drawings, the manufacturer will submit a set of re-producible of all the approved drawings and will also supply five sets of all approved drawings and five sets of manual of instructions per transformer to sub-station Design Directorate, HVPNL, Panchkula.

ONE SET OF ALL THE APPROVED DRAWINGS AND MANUAL OF INSTUCTIONS WILL BE SUPPLIED ALONGWITH EACH TRANSFRMER WITHOUT WHICH THE SUPPLY WILL NOT BE CONSIDERED AS COMPLETE SUPPLY.

26.2.1 Outline general arrangement drawings showing plan, front elevation & side elevation with all fittings and accessories etc. The following information must be specifically included on the drawings.

a.Make of transformer oil.

b.Electrical clearances, minimum as well as actual.

c.No. of radiator headers, number of radiator element in each header.

d.Small sketch showing un-tanking details.

e.Thickness of transformer tank bottom, side & top plates.

f.Type, shade, shade No. and thickness of transformer paint.

g.Roller, rail gauge sketch.

h.Weight of oil, bare copper weight windings, core, un-tanking mass, transportation mass and dimensions etc.

26.2.2Detailed of bushings showing plan, elevation, terminal details, mounting details make and type number incorporating electrical characteristics, description of various parts, total creepage/ & protected creepage distance, weight of oil, total weight of bushing , dimensions, short time current rating etc.

26.2.3Drawing showing HV & LV windings with arrangement of insulation and terminal connections.

26.2.4Schematic control and wiring diagram for auxiliary equipment like OLTC control gear, cooler control gear, Marshaling Kiosk. Detailed writeup for schematic shall also be supplied

26.2.5 Combined Rating & Diagram Plate.

26.2.6Valve schedule plate.

26.2.7 Core assembly drawing with flux density calculations.

26.2.8 Interconnection diagram between OLTC panel, Drive mechanism and marshalling kiosk.

26.2.9 Detailed calculations showing short circuit with stand capability due to radial and axial forces during short circuit. Also calculation for thermal withstand capability during short circuit.

26.2.10 Cable arrangement on the transformers.

26.2.11 Drawing showing connection of HV, LV lead with the respective bushing and their place of storage during transportation.SR. NO.DESCRIPTIONPARTICULARS

RequiredOffered

1Manufacturers Name

2Rating (MVA)

3Voltage Ratio (KV)

4Winding Connection

5Vector Group

6Number of Phase

7Frequency (Hz)

8Type of cooling

9Rating available at different cooling %

10Impedance data

aGuaranteed positive sequence impedance between HV-LV at 75 deg.C with 100% rating at

i. Principal Tap

ii. Maximum Tap

iii. Minimum Tap

bZero sequence impedance at principal tap

11Guaranteed losses at 100% rated voltage (excluding cooler loss) at 75 deg.C between HV and LV

aIron loss (KW) (max)

bCopper loss (KW) (max)

cGuaranteed cooler losses at

(i)100% load (max) (KW)

12Overall average weightage loss (KW) (Max.)

13Cooling equipment details

aNumber of coolers and rating as per % of transformer cooling equipment

bMounting

cFan motor data

iNumber per cooler and rating as % of cooler requirement (also indicate no.of spare fans)

iiType

iiiRating (KW)

ivLocked rotor current (Amps)

vTemp. range over which cooler control is adjustable (deg.c to deg.C)

dOil pump motor data

iNumber per cooler and rating as % of cooler requirement (also indicate no.of spare pump)

iiType

iiiRating (KW)

ivLocked rotor current (Amps)

vTemp. range over which cooler control is adjustable (deg.c to deg.C)

eType of oil pump and motor (whether oil submerged type)

fRadiator details

iOverall dimensions lxbxh (mm)

iiTotal weight with oil (Kg)

iiiTotal weight without oil (Kg)

ivThickness of Radiator tube (mm)

vType of mounting

14Thermal Data

aTemperature rise in top oil over an ambient of 50 deg.C

bTemp rise in winding by resistance measurement method over an ambient of 50 deg.C

cThermal time constant (Hours)

15Withstand time for three phases short circuit at terminals (secs)

16Over excitation withstand time (sec)

i1.25

ii1.4

iii1.5

17Bushings

aHigh voltage

i)Manufacturer

ii)Type

iii)Total creepage distance (mm)

iv)Protected creepage distance (mm)

v)Mounting

vi)Rated current (Amps)

bLow voltage

i)Manufacturer

ii)Type

iii)Mounting

iv)Total creepage distance (mm)

VProtected creepage distance (mm)

vi)Rated current (Amps)

CNeutral Bushing

i)Manufacturer

ii)Type

iii)Mounting

iv)Total creepage distance (mm)

v)Protected creepage distance (mm)

vi)Rated current (Amps)

18Is Vacuum filling required, if so state absolute pressure (mm of Hg)

19Total quantity of oil (ltrs)

20Tap changing equipment

a)Voltage class and current

b)Number of steps

c)Range

d)Step voltage

e)Type

f)Rated voltage of drive motor (volts)

g)No.of revolutions to complete one step

h)Time to complete one step on manual / auto operation (sec)

i)Power required (kw)

21Insulation level

a)HV windings

i)Lightning impulse withstand voltage

ii)Power frequency withstand voltage (kv rms)

b)LV Winding

i)Lightning impulse withstand voltage

ii)Power frequency withstand voltage (kv rms)

c)HV Bushing

i)Lightning impulse withstand voltage

ii)Power frequency withstand voltage (kv rms)

d)LV Bushing

i)Lightning impulse withstand voltage

ii)Power frequency withstand voltage (kv rms)

e)Neutral Bushing

i)Lightning impulse withstand voltage

ii)Power frequency withstand voltage (kv rms)

22Approximate dimensions

a)Tank (lxbxh) mm

b)Overall dimensions with (mm) coolers lxbxh

c)Shipping dimensions (mm) (lxbxh)

d)Height for untanking (mm)

e)Dimensions of largest (mm) package (lxbxh)

23Weights of transformer components

a)Core (Kg)

bWindings (Kg)

c)Insulation (Kg)

d)Tank and fittings (Kg)

e)Oil (Kg)

f)Untanking weight (heaviest piece) (Kg)

g)Total weight Kg

h)Weight of heaviest package KG

i)Total shipping weight (Kg)

j)Parts detached for transport

24Permissible overload (% of rating & time in minutes)

25Clearances

a)Minimum clearance between phases

i)In oil (mm)

ii)In air (mm)

b)Minimum clearance of HV winding to tank in oil (mm)

c)Minimum clearance of HV winding of earth in oil (mm)

d)Clearance between core (mm) and coil

e)Clearance between coil (mm)

f)Clearance between neutral to ground in air (mm)

26Conservator

a)Total volume (ltrs)

b)Volume between highest and lowest levels (ltrs)

27Capacitance values

a)HV to earth (pf)

b)LV to earth (pf)

28a)Type of oil preservation

b)Material of air cell

c)Continuous temp. withstand capability of the air cell

29 a)No.of pressure relief device provided

b)Operation pressure of pressure relief device

30Oil

a)Quality of oil

i)Moisture content (ppm)

ii)Max tan delta value (at 90 deg.C)

iii)Resistivity (ohm cm)

iv)Breakdown strength (kv)

v)Interfacial tension at 27 deg.C (min)

b)Quantity including 10% extra (Ltrs)

c)Standards applicable

31Core

a)Type of construction

b)Net core area (mm.sq)

c)Core material and grade used

d)Type of joint between core and yoke

e)Thickness of stamping (mm)

f)Percentage silicon content (%)

g)Maximum flux density in core at rated frequency at

i)90% voltage (wb/sq.m)

ii)100% voltage (wb/sq.m)

iii)110% voltage (wb/sq.m)

32Winding

a)Type of winding

b)Current density at rated load

i)HV (A/Sq.cm)

ii)LV (A/Sq.cm)

iii)Regulating winding (A/Sq.cm)

c)Conductor area

i) HV (sq.mm)

ii) LV (sq.mm)

Iii) Regulating winding

d)Maximum current density under short circuit

i)i) HV (sq.mm)

ii) LV (sq.mm)

e)Magnetising inrush current (Amps)

f)No load current (Amps) at rated frequency and at

i)90% voltage (wb/sq.m)

ii)100% voltage (wb/sq.m)

iii)110% voltage (wb/sq.m)

g)Magnetising current at rated frequency and at rated voltage

33Tank

a)Type

b)Material

c)Approx Thickness of

i)Sides (mm)

ii)Bottom (mm)

iii)Cover (mm)

34Radiator

a)Make

b)Material

c)Thickness

35Vacuum withstand capability of

a)Main tank (torr)

b)Radiators accessories (torr)

36Pressure withstanding capability of

a)Main Tank

b)Radiator and accessories

37Temperature indicators

a)OTI

i)Manufacturer

ii)Range

iii)Accuracy

b)WTI

i)Manufacturer

ii)Range

iii)Accuracy

c)RWTI

i)Manufacturer

ii)Range

iii)Accuracy

iv)Auxiliary supply used

38Terminal connectors

a)Make

b)Whether type tested

c)Governing standard

Note: If there is any change in the above GTPs, same shall conform to Technical Specifications/relevant ISS. If there is any change in GTPs, so warranted by specific make of equipment, same shall be taken care at the time of approval of drawings.

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