Kishenpur is a village situated on the bank of river Tawi, about 65 Kms. from Jammu, on Dhar-Udhampur Road. This small village came in news first during 1965, when villagers from border areas from Chhamb and Jourian villages affected by Indo-Pak War were put into camps in Kishenpur and adjoining village Manwal. After the shifting of displaced persons back to their villages this was a forgotten village and even now many citizens of the State are unaware of its fast development. With the approval of Dulhasti Hydroelectric project in 1985 the land of this village was selected and acquired by NHPC for construction of one of the largest grid stations of the country to pool and transmit power of upcoming hydroelectric projects of the state. In Nov.’ 1991 the construction and ownership of the substation passed on to POWERGRID and today this village is an important landmark in the power map of India.

Height above mean sea level : 480Mtrs.

Village Population : Approx. 2000

Max. Temperature : 45ºC

Min. Temperature : 01ºC

Rainfall : Moderate

Summer : May-June

Winter : Dec-Jan

Page | 1

KISHENPUR-A PROFILE

KISHENPUR-SALIENT FEATURES

Climatic conditions:-

Winter conditions : The peculiar location of Kishenpur in the hills results in heavy wind during night.

Summer conditions : Being located in a valley and presence of rocks, here temperature is very high during the day time, which cools off during nights.

Land area:-

Substation : 895.16 Kanals (Jammu District) Township : 193.13 Kanals (Udhampur District)

Page | 2

Page | 3

KISHENPUR – POWER POOL

S.NO NAME OF STATION OWNED BY INSTALLED CAPACITY

1. SALAL HYDRO NHPC 6X115 = 690.MW

2. CHAMERA HYDRO NHPC 3X180 =540 MW

3. CHENANI HYDRO PDD 5X5 = 25 MW.

4. URI HYDRO NHPC 4 X 120 = 480 MW

5. PONG HYDRO BBMB 6 X 60 = 360 MW.

6. BAIRA SUIL NHPC 3 X 60 = 180 MW.

S.NO NAME OF LINE / ICT DATE OF COMMISSIONING

1. 220KV SALAL - KISHENPUR - I 15-07-932. 220KV SALAL - KISHENPUR - II 15-07-933. 220KV KISHENPUR-UDHAMPUR I 15-07-934. 220KV KISHENPUR-UDHAMPUR -II 15-07-935. 220KV KISHENPUR-SARNA - II 06-09-946. 220KV KISHENPUR-SARNA-I 07-09-947. 220KV KISHENPUR-PAMPORE-I 09-06-968. 220KV KISHENPUR-PAMPORE - II 09-06-969. 220KV KISHENPUR-SALAL III 31-07-9610. 220KV KISHENPUR-SALAL – IV 31-07-9611. 220/400KV 315 MVA ICT-I 05-09-9712. 220/400KV 315 MVA ICT – II 05-09-9713. 400KV CHAMERA-KISHENPUR 05-09-9714. SERIES COMPENSATION

OF 220kV D/C PAMPOREI & II

02.06.99

15. 400kV S/C DULHASTIKISHENPUR -I

31.03.2000

16. 800kV KMTL –I ( CHARGED 31.03.200017. 800kV KMTL –II AT400kV

LEVEL )19.01.01

18. Kishenpur-Moga19. 800kV KMTL –1 (charged at 400kV) 29.04.2000

20. 800kV KMTL –2 (charged at 400kV) 19.01.2001

21. Dulhasti combined transmission system

22. 400kV Kishenpur- Wagoora – 1 29.10.2006

23. 400kV Kishenpur- Wagoora – 2 29.10.2006

24. Baghliar PDC

25. 400kV Kishenpur- Baglihar – 1 25.07.2008

26. 400 KV Kishenpur Baglihar-II 12.08.2008

Page | 4

KISHENPUR-MILESTONES

PSEB & JKPDD bays under O&M of Kishenpur Sub Station:

1. Udhampur Grid Station JKPDD:

a) 220KV Kishenpur-Udhampur-I

b) 220KV Kishenpur-Udhampur-II

2. Gladni Grid Station, Jammu JKPDD:

a) 220KV Salal-Jammu-I

b) 220KV Salal-Jammu-II

c) 220KV Jammu-Hiranagar

3. Sarna Grid Station, PSEB:

a) 220KV Sarna-Hiranagar

b) 220KV Kishenpur-Sarna-I

c) 220KV Kishenpur-Sarna-II

d) 220KV Sarna-Dasuya-I

e) 220KV Sarna-Dasuya-II

4. Hiranagar Grid Station, JKPDD:

a) 132KV Sewa-Hiranagar-I

b) 132KV Sewa-Hiranagar-II

5. Mahanpur Grid Station, JKPDD:

a) 132KV Sewa

Page | 5

b) 132KV Kathua

6. Kathua Grid Station, JKPDD:

a) 132KV Mahanpur

b) 132KV Sewa

KISHENPUR – Substation

S.No NAME OF BAY

VOLTAGE LEVEL

CONSTRUCTION AGENCY

CONSTRCTION PERIOD

1. SALAL- I 220 KV GENELEC/POWERGRID ’87 – JULY’932. SALAL- II 220 KV GENELEC/POWERGRID ’87 – JULY’933. UDH AMPUR-

I220 KV GENELEC/POWERGRID ’87 – JULY’93

4. UDHAMPUR – II

220 KV GENELEC/POWERGRID ’87 – JULY’93

5. TBC 220 KV GENELEC/POWERGRID ’87 – JULY’936. BUS COUPLER 220 KV GENELEC/POWERGRID ’87 – JULY’937. SARNA- I 220 KV TECHNO ELECTRIC ’91 – SEP’948. SARNA- II 220 KV TECHNO ELECTRIC ’91 – SEP’949. PAMPORE- I 220 KV TECHNO ELECTRIC ’91 – JUN’96

10. PAMPORE- II 220 KV TECHNO ELECTRIC ’91 – JUN’9611. KISHTWAR- I 220 KV TECHNO ELECTRIC ’91 – JUL’9612. KISHTWAR- II 220 KV TECHNO ELECTRIC ’91 – JUL’9613. SALAL- III 220 KV TECHNO ELECTRIC ’91 – JUL’9614. SALAL- IV 220 KV TECHNO ELECTRIC ’91 – JUL’9615. ICT – I 220/400 KV TECHNO ELECTRIC ’93 – SEP’9716. ICT – II 220/400 KV TECHNO ELECTRIC ’93 – SEP’9717. CHAMERA 400 KV TECHNO ELECTRIC ’93 – SEP’9718. MOGA- I 400 KV TECHNO ELECTRIC ’97 – SEP’9919. MOGA –II 400 KV TECHNO ELECTRIC ’97 – SEP’9920. Wagoora-1 400 KV IRCON ’2004 – 200621. Wagoora-2 400 KV IRCON ’ 2004 – 200622. BUS REACTOR 400 KV TECHNO ELECTRIC ’97 – SEP’9923. DULHASTI- I 400KV INDO POWER ’98 – SEP’99

Page | 6

24. SERIES COMP.PAMPORE-1&2

220KV BHEL ’98 - JUNE99

MAJOR EQUIPMENTS AT KISHENPUR

TRANSFORMER

RATING : 400/220 kV, 105 MVA, SINGLE PHASE COOLING : ONAN / ONAF / OFAF QUANTITY : 7 NOS. = 2 BANKS OF 3 PHASES AND ONE SPARE MAKE : BHEL

CIRCUIT BREAKER

RATING : 400kV, SF6 OPERATION : PNEUMATIC CLOSE & OPEN QUANTITY : 18 NOS. = 7 WITHOUT PIR + 11 WITH

MAKE : ABB

RATING : 220kV, SF6

OPERATION : PNEUMATIC CLOSE & OPEN QUANTITY : 4 NOS. MAKE : ABB

Page | 7

RATING : 220kV, SF6 OPERATION : PNEUMATIC OPEN & SPRING CLOSE QUANTITY : 14 NOS. MAKE : CGL

CURRENT TRANSFORMER

RATING : 400 kV, SINGLE PHASE MAKE : TELK, AREVA

RATING : 220 kV, SINGLE PHASE

MAKE : TELK, CGL, BHEL

CAPACITIVE VOLTAGE TRANSFORMER

RATING : 400 kV, SINGLE PHASE

MAKE : ABB, AREVA

RATING : 220 kV, SINGLE PHASE MAKE : CGL, WSI

RECORDERS AND FAULT LOCATERS

S. NO. NAME OF LINE / ICT / BUS RECORDER / FAULT LOCATER MAKE TYPE

01. 220KV SALAL - I DISTURBANCE RECORDER AREVA MICOM*

02. 220KV SALAL - II DISTURBANCE RECORDER AREVA MICOM*

03. 220KV SALAL - I & II DR & INBUILT FAULT AREVA MICOM*

Page | 8

LOCATER

04. 220KV UDH. - I DISTURBANCE RECORDER AREVA MICOM*

05. 220KV UDH. - II DISTURBANCE RECORDER AREVA MICOM*

06. 220KV UDH. - I & II DISTURBANCE RECORDER AREVA MICOM*

07. 220KV SALAL - III & IV DISTURBANCE RECORDER AREVA MICOM*

08. 220KV SARNA -I DISTRUBANCE RECORDER ABB INDACTIC65

09. 220KV PAMPORE - I FAULT LOCATER ABB RANZA

10. 220KV PAMPORE - II FAULT LOCATER ABB RANZA

11. 220KV PAMPORE - I & II DISTURBANCE RECORDER CSD IMS 8*

12. 220KV UDHAMPUR -I & II DISTURBANCE RECORDER AREVA MICOM*

13. 400KV CHAMERA DISTURBANCE RECORDER AREVA MICOM*

14. 400KV CHAMERA DISTURBANCE RECORDER AREVA MICOM*

15. 400kV MOGA-I DISTURBANCE RECORDER AREVA MICOM*

16. 400kV MOGA-II DISTURBANCE RECORDER AREVA MICOM*

17. 400kV DULHASTI-I DISTURBANCE RECORDER AREVA MICOM*

18. 400kV DULHASTI-I DISTURBANCE RECORDER AREVA MICOM*

19. 220KV BUS - I VOLTAGE ADAPT CR100

20 220KV BUS - I FREQUENCY ADAPT 3210

21. 220KV BUS - II VOLTAGE ADAPT CR100

22. 220KV BUS - II FREQUENCY ADAPT 3210

23. 400KV BUS - I VOLTAGE ADAPT 3210

24. 400KV BUS - I FREQUENCY ADAPT 3210

25. 400KV BUS - II VOLTAGE ADAPT 3210

26. 400KV BUS - II FREQUENCY ADAPT 3210

Page | 9

POPULATION OF SUBSTATION EQUIPMENTS

(220KV SIDE)

S.NO DESCRIPTION OF EQUIPMENT MAKE TYPE QTY.

1 Circuit Breaker ABB ELF SL4-1 4

CGL 14

2 Current transformer BHEL IS2705 15

TELK NPOU2LVZ 6

CGL ISOK:245/460/1050 27

3 Capacitive Voltage Transformer CGL CVE:245/1050/50 27

WSI CVE:245/1050 11

BHEL 2

ALSTOM CVEB:245/1050/50 1

ABB 245K/W/220N 1

4 Lightening Arrestors WSI 1.0-20001R(A)2000 1

ELPRO 9L11ZMU 42

Page | 10

POPULATION OF SUBSTATION EQUIPMENTS

(400KV SIDE)

S.NO DESCRIPTION OF EQUIPMENT MAKE TYPE QTY.

1 3×105 MVA 400/220/33 KV ICT BHEL Auto Transformer 2 UNIT+ 1 SPARE

2 400KV BUS REACTOR BHEL 01

3 400KV LINE REACTOR BHEL 02

4 CIRCUIT BREAKER ABB EL(V)FSL6-2(PIR)ELFSP6-21

18

5 CURRENT TRANSFORMER TELK NPOU2LVZ 388

ALSTOM IT-400 21

BHEL IS2705 28

6 Capacitive Voltage Transformer ALSTOM CVEB:245/1050/50

12

ABB 421KV/W/420N 18

7 Lightening Arrestors WSI 1.0-2000IR(A)2000 17

ELPRO 9L11ZMU 13

OBLUM METAVARMETALOXIDE

6

ALSTOM ZODIVER 6

Technical ParametersPage | 11

1. Total Transformation capacity : 630MVA

2. No. of Lines : 400 KV – 08 Nos.

a) (Kishenpur - Baglihar D/C)

b) (Kishenpur - Moga D/C)

c) (Kishenpur - Wagoora D/C)

d) (Kishenpur- Dulhasti S/C)

e) (Kishenpur- Chamera S/C)

: 220 KV – 12 Nos.

a) (Kishenpur –Salal-I&II D/C)

b) (Kishenpur - Salal III & IV D/C )

(Kishenpur-Sarna D/C)

c) (Kishnepur-Udhampur D/C)

d) (Kishenpur- Pampore D/C)

Page | 12

e) (Kishenpur – Barn D/C )

3. No. of Existing Bays :400 KV – 18 Nos. (08 Line Bay + 7 Tie Bay + 1

Bus Reactor bay + 2

ICT Bay)

220 KV- 18 Nos. (12 Line Bay + 2 ICT Bay

+FSC Bay+ 1 Bus Coupler

+ 1 TBC)

4. No. of 105 MVA, 400/220/33 KV ICTs : 07 Nos. (Including 01 Spare)

5. Bus bar Scheme : 400KV - One & Half Circuit Breaker.

220KV- Double Main & Transfer Bus

Page | 13

AUTO TRANSFORMER (TECHNICAL DETAILS):-

MAKE : BHEL

TYPE OF COOLING : ONAN/ONAF/OFAF

RATING HV&IV (MVA) : 42/63/105

40% 60% 100%

RATING LV (MVA) : 35

TEMP. RISE OIL : 40 ABOVE AMBIENT OF 50°C

TEMP. RISE WINDING : 55 ABOVE AMBIENT OF 50°C

CORE & WINDING (KG) : 54780

WT. OF OIL (KG) : 29580

TOTAL WEIGHT (KG) :123300

TRANSPORT WEIGHT (KG) : 67000

OIL QUANTITY (LITRE) : 34000

UNTANKING WEIGHT (KG) : 8000

FREQUENCY : 50 HZ

PHASE : SINGLE

CONNECTION : YNa0d11 FOR 3-PHASE BANK

TO INDIAN STANDARD : 2026

Page | 14

BUS REACTOR (TECHNICAL DETAILS):-

MAKE : BHEL

TYPE OF COOLING : ONAN

RATING VOLTAGE (KV) : 420

RATING CURRENT (A) : 87

RATING POWER (MVAR) : 63

TEMP. RISE OIL : 50 (OVER AMBIENT OF 50°C)

TEMP. RISE WINDING : 50 (OVER AMBIENT OF 50°C)

CORE & WINDING (KG) : 59410

WT. OF OIL (KG) : 34565

TOTAL WEIGHT (KG) :121970

TRANSPORT WEIGHT (KG) : 75000

OIL QUANTITY (LITRE) : 39730

UNTANKING WEIGHT (KG) : 8000

FREQUENCY : 50 HZ

PHASE : THREE

LIGHTENING IMPLUSE : 1300KVP (LINE

SWITCHING IMPLUSE : 1050 KVP (LINE)

Page | 15

SUBSTATION LAYOUT- General Arrangement

Placement of switchyard

Control Room placement

Fire fighting pump house placement

DG set placement

LT station placement

(ACDB, DCDB, Battery Bank & Battery Charges)

Identification of roads & rail tracks

Identification of boundary wall and fencing

Identification of approach roads

Space for colony and other infrastructures

Switchyard Layout

Single Line Diagram

Bus Switching Scheme

Normal rating with temperature rise, Short time current rating

Rating & insulation levels of the equipments

Bay numbering

Page | 16

Major factors deciding a layout

Standard factors

Electrical clearances

Heights of different levels & electric field

Variable factors

Shape of land & feeder orientation

Bus bar arrangement

Type of isolator used

Arrangement of lightning protection

Location of control room building, FFPH

Roads and rail tracks

Switchyard at Substation Kishenpur

Page | 17

SINGLE LINE DIAGRAM

Page | 18

Bus Bar Switching Schemes

Factors dictating choice of bus switching scheme

1) Reliability

No Power interruption during Bus fault

2) CB Maintenance

No Power interruption during CB maintenance. Taking out CB for maintenance shall be easy

3) Bus Bar Maintenance

No Power interruption during Bus bar maintenance

4) Simplicity of protection arrangements

Protection arrangements shall be simple for easy commissioning and regular checking

5) Ease of Extension

Extension of Bus bar necessary to take care of future expansion. Power interruption during such extension works.

6) Cost

Optimal techno-economic solution

Bus Switching Schemes

Single Main Bus Scheme

– With sectionaliser & without sectionaliser

Single Main & Transfer Bus Scheme

Double Main Bus Scheme

Double Main with by-pass isolator Bus scheme

Page | 19

Double Main & Transfer Bus Scheme

One & Half Breaker Bus Scheme

Double bus two breaker Scheme

Ring Bus Scheme

Page | 20

IN THE STATION ONLY TWO SCHEMES ARE USED OUT OF LISTED ABOVE

One & half breaker bus scheme for a 400KV system. Double main & transfer bus scheme.

1. SINGLE BUS SCHEME

Simplest and cheapest bus bar scheme

Maintenance and extensions of bus bars are not possible without shutdown of the substation.

Operation & maintenance of bus bar is easy.

2. SINGLE MAIN AND TRANSFER SCHEME

Individual CB can be taken out for maintenance on-load at a time.

The transfer bus coupler acts as the breaker for the circuit under by pass.

Individual circuits have a bypass isolator to connect to the transfer bus and this isolator will be closed during bypass operation of that particular circuit.

Page | 21

3. DOUBLE BUS SCHEME

Load will be distributed on both the buses and the bus coupler shall be normally closed.

For maintenance & extension of any one of the buses the entire load will be transferred to the other bus.

On load transfer of a circuit from one bus to the other bus is possible through bus isolators provided the bus coupler is closed and thereby two buses are at the same potential.

On load bypassing of any circuit for breaker maintenance is not possible.

4. DOUBLE BUS WITH BY-PASS SCHEME

Page | 22

This bus arrangement provides the facilities of a double bus arrangement & a main and transfer bus arrangement.

The bus to which the transfer bus isolator is connected can be used as a transfer bus also.

During the time a circuit is under bypass, the bus coupler will act as the breaker for the bypassed circuit.

5. DOUBLE MAIN AND TRANSFER SCHEME

In this bus scheme, in addition to the two main buses there will be a separate transfer bus also.

Since separate transfer bus is available there will be no need of transferring the load from one bus to the other bus unlike in a double main cum transfer bus arrangement.

Other features are similar to the one described in double bus with by pass arrangement.

Page | 23

6. BREAKER AND HALF SCHEME

In this scheme, two circuits have three breakers; the middle breaker ties the two circuits and hence is called the tie breaker.

Breaker or bus maintenance is possible without any shut down of the feeder

Even if both the buses are out of service, power can be transferred from one feeder to another feeder through tie breaker

7. DOUBLE BUS TWO BREAKER SCHEME

Each feeder is controlled by two breakers.

This arrangement is comparatively costlier than other scheme and hence followed in very important circuit only.

In this arrangement breaker maintenance for any feeder circuit is easily possible without any shutdown.

Page | 24

8. RING BUS SCHEME

As long as the ring is closed load has two sources of supply and any circuit breaker can be taken out of service without affecting the supply.

Extension of ring scheme is difficult.

No bus bar protection required.

Bus Switching Selection considerations

Reliability

Operation Flexibility

Ease of Maintenance

Short Circuit Level Limitation

Simplicity of Protection Arrangement

Ease of Future expansion

Land availability

Cost

Page | 25

Transmission Lines Materials

Conductor

Earth wire

Insulators

Conductor Accessories / Hardware’s

Earth wire Accessories

Conductor

Major item in any Tr.line

15 – 20 % of the line cost

Twin Moose (ACSR) Generally used in 400KV lines

Confirm to IS:398(Part-V) / IEC:1089

Other conductors, ACSR., Kundah., Zebra., Morkulla., Bersimis, Coyate etc

Conductor Specifications

Strands & Dia 54 / 3.53mm Aluminum+7/3.53 mm steel

Number of strands:

Steel 1

1st steel layer 6

Page | 26

1st Alu. layer 12

2nd Alu. Layer 18

3rd Alu. layer 24

Sectional Area 528.5 Sq.mm

Overall Dia 31.77 mm

Unit Mass 2.004 Kg/M

DC resistance at 20 Deg 0.05552 Ohm/KM

Current Carrying capacity 950 Amps @ 28 Deg

Minimum UTS 161.2KN

Earth wire

Used to carry the short circuit current

Protection against Lightning

Two earth wires are used in 400KV lines

Shielding angle;

Single Circuit # 20 Degrees Double Circuit # 10 Degrees

Specifications of E/W

a. 7/9 SWG ( 7/3.66mm, 7 strands of Gal. steel)

b. Overall Dia – 10.98mm

Page | 27

c. Unit mass - 583Kg/Km

d. DC resistance – 2.5 Ohms/KM

i. UTS - 68.4KN

Insulators

Purpose

Types;

o Pin, Disc, Long Rod, Anti-fog, Polymer

o 90KN, 120KN & 160KN

Construction of a Insulator

Specification’s:

o Rated Voltage : 11KV

o Creepage Distance : 315mm for 120KN

o 330mm for 160KN

Conductor Accessories

Single Suspension Fittings

Double Tension Fittings

Bundle Spacer

Rigid Spacer

Vibration Damper

Balancing Weight

Mid-span Joint for ACSR

Repair Sleeves

“T” Connector

Earth Wire Accessories

Suspension Clamp

Tension Clamp

Flexible Copper Bond

Vibration Damper

Mid-span Compression Joint for E/W

Page | 28

220 KV T.L. SERIES COMPENSATION (FSC)

220 KV double circuits Kishenpur–Pampore line, requirement with Uri Transmission

system & belonging to Power Development Department of Govt. of J&K, is a vital link between

Kashmir valley and rest of the country. During winters the power requirement in the valley is

met with this line, while generation at Uri during summer is evacuated on this line. This line

had a limitation of 150 MW power flows, before used to it become unstable. This caused under

utilization of thermal limit of line. The installation of 220 KV series capacitor on these lines has

increased the power handling capacity of line by 67%.

Page | 29

Technical Data of FSC:

Technical Particulars of series capacitor banks:

Rated output : 3 x 19.2MVar

Rated Voltage : 24kV

Rated current : 800A

Rated Frequency : 50Hz ± 3%

No. of phases : 03 (each bank independent)

Rated capacitance per phase : 106.1 µF

Total units in bank : 96

No. of series section per phase (bank) : 4 No.

No. of units in parallel per series group : 24

Watt loss / KVar : 0.20 W/KVar

Technical Particulars of series capacitor units:

Rated output : 292 kVar

Rated voltage : 7.25 kV

No. of bushings & type : 2 Nos. Soliderable Type

Rated Frequency : 50Hz ± 3%

No. of phases : Single

Rated capacitance : 17.68 µF

Watt loss / KVar : 0.20 W/KVar

Current setting for Auto-Operation: FSC come into service when line-current > 160A & come out of service when line current < 60A.

Page | 30

TRANSFORMER

A transformer is a device that transfers electrical energy from one circuit to another

through inductively coupled conductors—the transformer's coils. A varying current in the first

or primary winding creates a varying magnetic flux in the transformer's core, and thus a varying

magnetic field through the secondary winding. This varying magnetic field induces a varying

electromotive force (EMF) or "voltage" in the secondary winding. This effect is called mutual

induction.

If a load is connected to the secondary, an electric current will flow in the secondary winding

and electrical energy will be transferred from the primary circuit through the transformer to

the load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in

proportion to the primary voltage (Vp), and is given by the ratio of the number of turns in the

secondary (Ns) to the number of turns in the primary (Np) as follows. By appropriate selection

of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be

"stepped up" by making Ns greater than Np, or "stepped down" by making Ns less than Np.

Power transformers at Grid

AUTOTRANSFORMER

Page | 31

An autotransformer has a single winding with two end terminals, and one or more terminals at intermediate tap points. The primary voltage is applied across two of the terminals, and the secondary voltage taken from two terminals, almost always having one terminal in common with the primary voltage. The primary and secondary circuits therefore have a number of windings turns in common. Since the volts-per-turn is the same in both windings, each develops a voltage in proportion to its number of turns. In an autotransformer part of the current flows directly from the input to the output, and only part is transferred inductively, allowing a smaller, lighter, cheaper core to be used as well as requiring only a single winding .However, a transformer with separate windings isolates the primary from the secondary, which is safer when using mains voltages.

An adjustable autotransformer is made by exposing part of the winding coils and making the secondary connection through a sliding brush, giving a variable turns ratio. Such a device is often referred to as a variac.

Autotransformers are often used to step up or down between voltages in the 110-117-120 volt range and voltages in the 220-230-240 volt range, e.g., to output either 110 or 120V (with taps) from 230V input, allowing equipment from a 100 or 120V region to be used in a 230V region.

SWITCH GEAR

Circuit Breakers Relays Current Transformer

Isolators Voltage Transformer

Switches

CIRCUIT BREAKER

Page | 32

A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.

Circuit breakers - functions

Carries current when closed

Withstands voltage when open

Withstands fault currents for short

Can interrupt load currents

Can interrupt fault currents

Can interrupt small inductive & capacitive currents without creating excessive

overvoltage’s

CATEGORISATION - There are different ways of classifying circuit breakers. One way is by the method used for arc quenching:-

a) Oil-circuit breakersb) Air blast circuit breakers

c) Sulphur hexafluoride circuit breakersd) Vacuum circuit breakers

On the basis of operating mechanism:-

a) Spring operated circuitsb) Solenoid operated circuit breaker

c) Pressure operated circuit breaker

Circuit breakers can also be divided into broad categories on account of its operation. These are:-

a) Fixed trip type – These are the breakers which can be closed on faults and the breaker will trip only after completing the closed operation.

Page | 33

b) Trip free type - These are breakers which do not complete closing operation if tripping signal on account of a fault exists, the breaker shall start tripping operation before the contact actually meets.

OIL CIRCUIT BREAKER: This Circuit Breaker is of single break type. These normally comprise of 2 sections: 1 upper compartment containing the arc control device and fixed and moving contacts and a lower supporting compartment. The arc control device is contained in a bakelised paper enclosure which is in turn in a porcelain insulator. Support for this compartment is provided by porcelain or bakelised paper support insulators. An insulating link passing through the support chamber drives the moving contact.

AIR BLAST BREAKERS: In the case of air blast breakers also, the interrupters are insulated from earth b means of porcelain insulators, the number being determined by the system voltage. Normally support insulators may carry up to 4 interrupter units. The air supply blast pipe to the interrupter units may be mounted one above the other and fed via bypass blast pipes or on branches from a common point at the top of the support insulator. A large diameter blast valve controls the flow of the air from the local air receiver to the interrupting units. The whole of the operating mechanism of the circuit forms an electricity operated trip coil. Isolation in this type of circuit breaker is achieved by keeping the interrupters open and the contact gas is permanently pressurized. The loss of the air in the pressurized circuit breaker will result in either its reclousure or loss of dielectric strength across the open contacts. Such an occurrence could prove disastrous to the system.

SF6 CIRCUIT BREAKER: This type of circuit breaker is of similar construction as the dead tank bulk oil volume type of circuit breaker, but to principle of current interruption is similar to the air blast circuit breaker. It doesn’t therefore represent a new conception of circuit breaker but simply employs a new arc extinguishing medium named SF6. The success of the circuit breaker depends solely on the high arc interrupting performance of the gas i.e. when it is broken down under electrical stress, it will very quickly reconstruct itself. It is 5 times heavier than air and has approximately twice the dielectric strength. The circuit breaker is completely sealed and operates as a closed system which means that no flame is emitted during operation and noise level is considerably reduced.

VACUUM CIRCUIT BREAKER: In a vacuum circuit breaker, two electrical contacts are enclosed in a vacuum. One of the contacts is fixed, and one of the contacts is movable. When the circuit breaker detects a dangerous situation, the movable contact pulls away from the fixed contact, interrupting the current. Because the contacts are in a vacuum, arcing between the contacts is suppressed, ensuring that the circuit remains open. As long as the circuit is open, it will not be energized. Vacuum circuit breakers are very durable, and they are designed

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to last for an extended period of time. These electrical safety devices can be made with a variety of materials, depending on the need and the preference of the manufacturer. As with other devices used to interrupt current for safety, vacuum circuit breakers are given a rating which indicates the kind of conditions they can handle. When people install circuit breakers, they must confirm that the breaker they are using is suitable for the conditions; a breaker which is rated too low can fail catastrophically.Out of these, circuit breakers used in Kishenpur S.S are:-1. Gas circuit breaker 2. SF6 circuit breaker

FOR 200KV SIDE FOR 400KV SIDE

Gas circuit breaker SF6 circuit breaker

Voltage : 245KV Voltage : 420KV Operation: spring-spring Operation : spring- pneumatic

(Close-open) (Close- open)

Make: Crompton Greaves Make: Crompton Greaves

RELAYSA protective relay is a device that detects the fault and initiates the operation of the circuit breaker to isolate the defective element from the rest of the system.

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Fundamental Requirements of Protective Relaying

In order that protective relay system may perform its function satisfactorily, it should have the following qualities:

a) Selectivityb) Speedc) sensitivity

d) reliabilitye) simplicityf) economy

(i) Selectivity: It is the ability of the protective system to select correctly that part of the system in trouble and disconnect the faulty part without disturbing the rest of the system.

(ii) Speed: The relay system should disconnect the faulty section as fast as possible for the following reasons:

(a) Electrical apparatus may be damaged if they are made to carry the fault currents for a long time.

(b) A failure on the system leads to a great reduction in the system voltage. If the faulty section is not disconnected quickly, then the low voltage created by the fault may shut down con- summers’ motors and the generators on the system may become unstable.

(c) The high speed relay system decreases the possibility of development of one type of fault into the other more severe type.

(iv) Reliability: It is the ability of the relay system to operate under the pre-determined Condi- ions. Without reliability, the protection would be rendered largely ineffective and could even become a liability.

(v) Simplicity: The relaying system should be simple so that it can be easily maintained. Reli- ability is closely related to simplicity. The simpler the protection scheme, the greater will be its reliability.

(vi) Economy: The most important factor in the choice of a particular protection scheme is the economic aspect. Sometimes it is economically unjustified to use an ideal scheme of protection and a compromise method has to be adopted.

TYPE OF RELAYS

Induction Relays: Electromagnetic induction relays operate on the principle of induction motor and are widely used for protective relaying purposes involving a.c. quantities. An induction relay

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essentially consists of a pivoted aluminum disc placed in two alternating magnetic fields of the same frequency but displaced in time and space. The torque is produced in the disc by the interaction of one of the magnetic fields with the currents induced in the disc by the other.

Over current Relay (non-directional): This type of relay works on the induction principle and initiates corrective measures when current in the circuit exceeds the predetermined value. The actuating source is a current in the circuit supplied to the relay from a current transformer. These relays are used on a.c. circuits only and can operate for fault current flow in either direction.

Directional Over current Relay: When a short-circuit occurs, the system voltage falls to a low value and there may be insufficient torque developed in the relay to cause its operation. This difficulty is overcome in the directional over current relay which is designed to be almost independent of system voltage and power factor.

Distance or Impedance Relays: Their operation is governed by the ratio of applied voltage to current in the protected circuit. In an impedance relay, the torque produced by a current element is opposed by the torque produced by a voltage element. The relay will operate when the ratio V/I is less than a pre determined value.

i) Definite-distance relay which operates instantaneously for fault up to a pre-determined distance from the relay.

(ii) Time-distance relay in which the time of operation is proportional to the distance of fault from the relay point. A fault nearer to the relay will operate it earlier than a fault farther away from the relay.

Differential Relays: A differential relay is one that operates when the phasor difference of two or more similar electrical quantities exceeds a pre-determined value. The difference between the incoming and outgoing currents is arranged to flow through the operating coil of the

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relay. If this differential current is equal to or greater than the pickup value, the relay will operate and open the circuit breaker to isolate the faulty section.

POPULATION OF PROTECTION RELAYS (400&220 KV SIDE)

S.NO Description of equipment Type of protection

Name of protection

Quantity

1 400/220 KV ICT- I and II DIFFERNTIAL DOUBIAS 2

OVERFLOW HV &IV

RATUB 4

REF RADHD 2

BACK UP O/C & E/F

CDD 4

OVERLOAD RELAY

RXIG 21 2

2 400/220 KV BUS BARS DIFFERNTIAL RADSS 4

3 LINE PROTECTION DISTANCE LZ 96 6

4 LINE PROTECTION DISTANCE MICOMP442 14

5 LINE PROTECTION DISTANCE SIPROTEC 2

6 LINE PROTECTION DISTANCE RAZFE 11

7 LINE PROTECTION DISTANCE MICOM P437 1

8 LINE PROTECTION DISTANCE OPTIMHO 4

CT – Current Transformer

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Transforms the primary current to a lower value suitable for meters and protection

relays.

Maximum secondary current is usually 1 A or 5 A (amperes).

Maximum (rated) primary current to secondary current given by C.T. Ratio, e.g. 500/1,

1200/1 etc.

INTERNAL DESIGN There is one conductor which carries the primary current and it is connected in series

with the electrical circuit. The secondary current is taken from the coils which are

mounted around the primary conductor. The number of secondary coils may vary based

on the requirement. Standard is 3 and 5 coils. Secondary current is normally 1 A or 5A.

INTERNAL DESIGN

CONSTRUCTION

Normally the purpose of the various secondary coils is as given below –

a) Coil or Core-I : Protection

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b) Core –II : Protection

c) Core – III : Metering

d) Core – IV : Protection

e) Core – V : Protection

TYPES OF CT

There are basically two kinds of CTs:

a) Dead tank type b) Live tank type

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Primary

conductor

(insulated)

extended to tank

at bottom.

Primary conductor & Secondary

windings in top tank. Secondary cables brought

down to Terminal Box at

bottom

MAIN FUNCTIONS OF CT

Electrically isolates the instruments and relays from High Voltage side.

Measures / monitors current.

Used in measuring power flow.

Senses abnormalities in current for system protection.

CVT (Capacitor Voltage

Transformer

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CVT – Purpose of Use

Capacitor voltage transformer (CVT) is connected in between high voltage line and ground to provide proportionate low voltage on the secondary side to meters & protective relays.

Also used for PLCC

Function

Electrically isolate the instruments and relays from High voltage side.

Measure / Monitor voltage.

Measure power flow.

Senses abnormalities in voltage for system protection.

Traps communication signals for PLCC.

CONSTRUCTION

It consists of Coupling Capacitor which acts as a voltage divider and one Electro Magnetic Unit (EMU) which transforms medium voltage to standard low voltage.

The coupling capacitor active part consists of large number of oil impregnated paper or paper & film capacitor elements connected in series. Capacitor tissue paper and pure aluminum foils are used for making capacitor elements.

The EMU tank consists of a medium voltage transformer, damping element and surge protection device. This unit is housed inside a steel tank

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Lightning Arrester or Surge Arrester

Method of Connection

Why Surge arrestor is required?

• Security guard at entry of Sub Station to block entry or to protect against surge voltages

• Electrical networks may be subjected to high voltage high frequency surges due to switching surges, lightening, load rejection, single phase faults etc.

• These disturbances take form of traveling waves with high amplitude and steep wave fronts

• Disturbances if reach terminal of equipment may cause extensive damage if exceeds BIL, SIL.

• Accordingly proper insulation co-ordination is done by providing Surge Arrestors

• Generally provided at line entry and near Transformer terminal in Sub Station

• Whenever a surge comes ,it should be grounded through non linear resistors provided in SA

• A good surge arrestor should have:-

I. Rapid response to impulse O/V

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II. Independent of wave polarity

III. High thermal capability

IV. Consistent behavior

Principles of operation

• When a surge occurs by direct stroke or through traveling wave from transmission line due to atmospheric or system disturbances, the material inside the LA (ZnO elements) start conducting and provides a path for the surge to flow to the ground.

• For normal operating voltage the material inside the LA is non conductive and provides open circuit between the conductor and the ground.

SELECTION OF SURGE RATINGSELECTION OF SURGE RATING

Objective: To select the lowest rated surge arrester that will have

• Satisfactory service life on the power system

• Which will provide adequate protection of equipment insulation

An arrester of minimum practical rating is generally preferred because it provides the greatest margin of protection for the insulation.

The use of higher rating

• Increases the capability of the arrester to survive on the power system, but

• reduces the margin of protection it provides for a specific insulation level

• ARRESTER SELECTION MUST STRIKE A BALANCE BETWEEN ARRESTER SURVIVAL AND EQUIPMENT PROTECTION.

WAVE TRAP

It is an equipment which is used to block the High frequency Carrier signals from

entering into power system.

It is installed in the phase which is used for PLCC.

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How it Looks

CONSTRUCTION

It is basically an Inductive coil of value in mill Henry.

To discharge the surges, one LA is provided inside the WT.

Mounting is done some times over the Coupling Capacitor and sometimes separately on support insulators depending on design. Sometimes hung from gantry.

ISOLATOR

Isolator is a device which is used to isolate an Electrical network for carrying out maintenance.

Purpose of use of Isolator & CB appears to be same. Only difference is that in case of Isolator there is no control for the Arc generated during make and break.

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Therefore an Isolator is to be operated only when there is no power flow in the circuit.

Earth switch to be closed only when isolator main contact is open and there is no voltage on E/S Side of isolator.

Types of Isolator

A) Based on arrangement

i) Horizontal Single Break or Centre Break (HCB)

ii) Horizontal Double Break (HDB)

iii) Tandem Isolator (HCB)

iv) Pantograph Isolators

B) Based on phase

Three phase/ double phase/ single phase

C) Based on Earth switch

i) Without E/S

ii) With 1 E/s

iii) With 2 E/S.

POWER LINE CARRIER COMMUNICATION

PLCC means Power Line Carrier Communication. Using the EHV Transmission line as a medium, the link is established among the stations connected with the Transmission network. It is used to serve three purposes mainly. The purposes are: For Voice communication. For data transmission. For transmission of carrier-aided trip signal for reduction of tripping time for the remote

Circuit breaker or in other words, reduction of fault feeding time during occurrence of fault in the Transmission line.

ADVANTAGES OF PLCC High reliability as that of the power lines Low capital and running cost

Disadvantages Limited bandwidth of 4 KHz Low speed of data transfer (typical 1200 baud, transfer of file comprising of graphics size

of 1 MB take minutes ) Needs separate Battery/Battery chargers for reliable DC supply

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PRINCIPLE OF OPERATION OF PLCC

A carrier frequency in the range 36 to 500 KHz is generated in a high frequency oscillator. It is then amplified, modulated by speech and other super – imposed signals like telemetering, teleprotection etc. whenever required and transmitted over power lines.

Coupling equipments (i.e. coupling device and Coupling capacitor) are used for isolation of Carrier equipment from high tension voltage and providing a low impedance path for the carrier frequency. In addition wave traps are used to confine the carrier current signals between the two Carrier Equipment located at respective substations.

Basic equipments for PLCC are:

a. Outdoor equipments :i. Line Trap

ii. Capacitive Voltage Transformers (CVT)/Coupling capacitors ( CC )iii. Line matching unit with protective device ( Coupling device : CD ) iv. Co-axial cable.

b. Indoor equipments :

i. Power line Carrier set

ii. Dialing Exchange & Phone sets.

iii. Remote Terminal Unit (RTU), Interface Cubicle and Modem.

iv. Protection coupler.

v. Line trap: Normally, operating frequency range of PLCC system is from 50 KHz to 500 KHz. The line trap is basically an inductance of rating 0.5/1.0 MHz depending upon the voltage level (132KV / 220/400KV). It blocks the PLCC signal to enter into the bus. (Impedance ώ = 2π f L).

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vi. CVT / CC: Normally rating is 5500pF. It allows the PLCC signal to follow its defined path. (impedance ώ = 1/ 2π f C )

vii. Line matching unit (LMU/CD): It matches the impedance of the PLC set with that of the Tr. Line for Maximum power transfer. It is also fitted with the protective device.

viii. Co-axial cable: It is an armored cable of low-loss property. There are three layers. Inner most layers are single core copper conductor called “hot point”. Next to it is Copper mesh which is to be earthed. Outermost layer is steel tape armor for

environment protection.

Types of coupling mode

a. Phase to ground – is the primitive type in which only one line trap, one CC and one LMU are involved. Merit: Cheap. Demerit: many, the biggest is earth is the return path and due to its non-uniform resistivity, signal attenuation is very high. Speech communication may be ok but not recommended for data / protection signaling.

b. Phase to Phase coupling: Best option for single circuit line. Two sets of outdoor equipments are installed in two phases. Conductor is the return path and in the case of one set O/D faulty, it becomes Ph/G coupling in which at least speech is possible.

c. Inter-Circuit coupling: Best among the entire coupling mode. But only possible in double circuit line. It is basically phase to phase coupling using one conductor from each circuit.

POWERGRID IS ADOPTING ONLY PHASE TO PHASE COUPLING FOR ALL THE LINES

Data Transmission

Field data is acquired using CT/PT, breaker, isolator, transformer tap.

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ii. All above are terminated in a SIC (System Interface Cubicle) which is a cubicle full of Transducers for analog data and Relays for digital data.

Iii. Output of transducers are 4 -20mA (DC) depending upon the value of the Analog measured. Output of the relays is DC voltage depending upon the condition of the CB /

Isolator.

iv. All these outputs are fed to the RTU (remote terminal unit) which is a telemeter trans-receiver and which converts the analog input into digital signals (A to D conversion) and prepares data packets.

v. These data packets are fed to the PLCC using MODEMs which is an equipment runs in FSK (frequency shift keying) mode. The Modem normally generates an audio frequency called “centre frequency”. It starts generating some other defined frequency as soon as the keying is done by the RTU data packet. (2520 ± 60).

vi. Finally, the modem output is fed to the “data input port” or the port known as “superimposed channels” of the PLC set which ultimately sends the same to the next station. Use of TBF is required in the intermediate station for isolation of Pilot frequency.

vii. At the other end, the RF modulated data packet enters into the PLC where the signal gets RF & IF demodulated and finally comes to audio level. This signal is fed to a Modem of frequency matching with the Transmit end.

vii. Finally, the signal is fed to the Front end computer where the actual data is visualized.

viii. In most of the cases under ULDC scheme, the PLCC & modem data is further connected to the Wideband network (Microwave or Optical Fiber ) to reach up to the destination Front end Computer.

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PLCC SCHEMES AT KISHENPUR

S.NO Name of Feeder Terminal Equipments

1 220KV SALAL I&II 6515R2+6710+6519(BPL) FREQ462KHz, 208KHz

2 220KV UDH I&II ETI-22+NSD50+ESD70C(HBB)FREQ-488KHz, 496KHz

3 220KV SALAL-IV 6515R2+6710+6519(BPL) FREQ382KHz,368KHz

4 220KV-III ETI21+NSD50(ABB)FREQ-156KHz 164KHz

5 220KV SARNA I&II ETI22+NSD50+ESD70D(ABB)FREQ-460KHz,468KHz

6 220KV SARNA I&II ETI21+NSD50(ABB)FREQ-352KHz,256KHz

7 220KV SARNA I&II ETI21+NSD50(ABB)FREQ-404KHz,400KHz

8 220KV PAMPORE ETI21+NSD50(WSI)FREQ-180KHz,204KHz

9 400KV CHAMERA ETI 21 (ABB)

10 400KV CHAMERA ETI21+NSD 61(ABB)FREQ-240KHz,296KHz

11 400KV CHAMERA ETI21+NSD61(ABB)FREQ-372KHz,324KHz

12 400KV WAGORA-I 9505+6710(BPL) FREQ228/248200/220KHz

13 400KV WAGORA-II 9505+6710(BPL) FREQ196/216188/184KHz

14 BAGLIHAR-I&II 9509+6710(BPL)

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