132 Kv Substation Traning Report at Haldia

2.HALDIA 132/33/11KV SUB-STATION

Haldia sub-station is a secondary grid(Transmission and step down) outdoor type sub-station.

It mainly receives power at 132KV from Kolaghat Thermal Power Station. Its incoming feeders are-

a) NIZ-1b) NIZ-2c) NH(D)d) HPLe) TPCL-1f) TPCL-2

It also receives power at 33kv from RENUKA SUGAR Company.

It serves power to the following purpose

1) It transmits power to S.E.Rly at 25 KV by two circuits, using two 132/25KV transformer (10MVA)

2)There are two 132/33kv(Rating 50MVA&31.5MVA) transformer operating in parallel which step down 132kv to 33kv and deliver it to the two 33kv busbar(Bus A and Bus B).

3) 33 KV power is transmitted from the two 33KV Bus-bars(Bus A & Bus B) by the feeders as follows:-

a) HRELb) EXIDE-2c) IOC PIPELINEd) HINDUSTAN LEVERe) IOC REFINARYf) GLYCHEMg) KSHUDIRAM NAGARh) EXIDE-1i) CPT-1

4) The substation also transmits power at 11kv by three 33/11kv transformer(two of rating 6.3MVA and one of 5MVA).

3.CIRCUIT EQUIPMENTS IN THE SUB-STATION

3.1 ISOLATOR

In electrical network system it is often desired to disconnect apart of the system for general maintenance and repair. For this purpose isolator is needed, which can break the system physically. Generally isolator is a mechanical switching device and they are operated under no load condition to avoid heavy flashing. So it should never be opened until the Circuit Breaker in the same circuit has been opened and should always be closed before the circuit breaker is closed.

At Haldia 132/33/11 KV Substation two types of isolators are used. They are:-

a) Single Breakb) Double Break

SINGLE BREAK ISOLATOR DOUBLE BREAK ISOLATOR

3.2 CIRCUIT BREAKER

Circuit Breakers are mechanical switching device designed to close or open members thus making or breaking an electrical circuit under normal condition as well as under abnormal condition, i.e. no load, full load and fault condition. The breaker are so designed that they can be operated manually under normal condition and automatically under faulty condition. For this purpose they use different relays.

SF6 CIRCUIT BREAKER

At Haldia 132/33/11KV Sub-Station generally SF6 Breaker are used. The specification

of breaker of different companies used in this sub-station is given below:-

3.2.1 ALSTOM:

Breaker serial no- 030987Type-SF6 circuit breaker FX-11Rated voltage- 145 kvNormal current- 1600AFrequency- 50HzLightning impulse withstand voltage- 650kvFirst pole-to-clear factor- 1.5Short time withstand current- 31.5kA for 3 secondsShort circuit breaking current- a) Symmetrical-31.5kA b)Asymmetrical-37.2kAShort circuit making current-80kAOut of phase breaking current-7.9Operating sequence-0-0.3s-CO-3min-COSF6 gas pressure at 200c 1013pa-6.3barTotal mass of circuit breaker-1300kgReference standard-IEC-56Year of manufacture-2001Customer-West Bengal State Electricity BoardOrder no.-p&s/p-38/2000/(PC-II)/ALSTOM/SP2High voltage switchgear, Chennai, India

3.2.2 ABB

Breaker serial no-OHB0632Rated voltage-36 KVNormal current-1250AFrequency-50HzInsulation level -95kV/200kV(peak)Short time withstand current-31.5KAShort time making current-80KAOperating sequence-0-0.3s-CO-3min-COClosing coil supply voltage-220v DCOperating coil supply voltage-230V DCMotor supply voltage -230 V ACMass(approx)-900kgInstruction manual-1VDU-23005-YNSF6 GAS PRESSURE-380kPa(abs) at 200c

3.2.3 CROMPTON GREAVESBreaker serial no-23288CType-30-SFGP-20ARated voltage-36 kVNormal current-1250AFrequency-50HzLightning impulse withstand voltage-170KVFirst pole-to-clear-factor-1.5Short time withstand current-25kA for 3secondsShort circuit breaking current- 25 kAShort circuit making current-63kAOperating sequence-0-0.3s-CO-3min-COSF6 gas pressure (normal)-5kg/cm2

Total mass of SF6 gas-1.7kgTotal mass of circuit breaker-750kgGas pressure (alarm)-4.5kg/cm2

Gas pressure (lockout)-4.0 kg/cm2

Rated coil volt-220V DC (closing),220V DC (tripping)Motor volt-230V AC, auxiliary circuit-230v 50HzRated power frequency withstand volt-80KV (rms)Reference standard-IEC-62271-100Year of manufacture-2006Customer- West Bengal State Electricity BoardLOI/PO no-p&s/p-32/2000/ (PC-III)/28P2

3.2.4 AREVABreaker serial no-101498Type –GL312 (132KV)Rated voltage- 145KVNormal current- 3150AFrequency – 50HzLightning impulse withstand voltage (peak)-650kVFirst pole-to-clear-factor-1.5Short time withstand current- 40kA for 3 secondsShort circuit breaking current- a) Symmetrical-40kA b)Asymmetrical-44.8kAShort circuit making current (peak) -100kAOut of phase breaking current-10kAOperating sequence-0-0.3s-CO-3min-COSF6 gas pressure at 200c 1013Pa-0.74mpa(abs)Total mass of SF6 gas-12kgTotal mass of circuit breaker-1534kg

Reference standard-IEC-62271-100Year of manufacture-2007Closing time of rated control voltage -91msTripping time of rated control voltage -41msCustomer- West Bengal State Electricity BoardOrder no-p&s/p-32/2005/ (PC-III)/27P2High voltage switchgear, Chennai, India

3.2.5 BHEL

Breaker serial no- 403541Type-SF6 14KV 3APIEGRated voltage- 145kvNormal current- 3150AFrequency-50HzLightning impulse withstand voltage (peak)-650kVRated one minute power frequency (volt)-275kvFirst pole-to-clear-factor-1.5Short time withstand current- 40kA for 3 secondsShort circuit breaking current- a) Symmetrical-40kA b)Asymmetrical-44.8kA c)Equivalent- 10000MVA d) Line charge current -50AShort circuit making current (peak) -100kAOperating sequence-0-0.3s-CO-3min-CORated pressure of hydraulic operating mechanism-313SF6 gas pressure at 200c-7.5bar (abs), 6.7(alarm)and LO 6.5barTotal mass of SF6 gas-30kgTotal mass of circuit breaker-2045kgReference standard-IEC-56/IS2156Year of manufacture-2001Closing coil voltage-220V DCTripping coil voltage -220V DCCustomer- West Bengal State Electricity Board

3.3 RELAYS

Most of relays used in power system operate by current and/or voltage and it is supplied by the secondary of the C.T or P.T connected to the system elements which are to be protected. In the sub-station we have an idea that most of relay are electromagnetic type or induction type.

DIFFERENT TYPES OF RELAY

The different types of relays used in thi sub-station are given below

3.3.1 OVER-CURRENT RELAY:

It operates when the system takes more current than the safe operating current that is also predetermined in the relay. The disc of the relay rotates and it makes the trip circuit and alarm circuit and the flag I dropped from which we can understand that the relay has been operated.

The over-current relays used in the substation are of following ratings:

132kV side Maker’s name- Easun Reyrelle

Sl.no- HR0104447

33KV side type- CDG AUG- VOLTS, C.T.see-lamp.5-2 amps,50 Hz

Sl.no- 140039460018002

11KV side In-5A, M2-0.5

Sl.No- HR0034734

25KV side type- CDG, 0.2-0.8A, 50Hz AC and type- CAG, 2.5-5 A

Sl. No- M14191524

3.3.2 EARTH FAULT RELAY:

It operates when an earth fault occurs in the system where it is connected. Although an earth fault and over current relay are the same in construction, still they operate on different principle.

The earth fault relay used in sub-station are of following ratings:

132kv side 110V AC 50Hz,450 lag

Maker’s name- Easun Reyrelle

Sl. No- HR0105250

33 KV side Vx- 24-250AC, use Rext 2700Ω for 220-250v

Sl. No- 140036050016002

11 KV side In-5A,M2-0.1

Sl. No- HR0034734

25KV traction type – CAG,0.1-0.4A- 50Hz AC

Sl.No- M141529

3.3.3 IMPEDANCE OR ZONE PROTECTION RELAY

It can define a fault in a fixed zone in the transmission line. this relay will operate when their V/I ratio changes with respect to its pre-determined value.

3.3.4 BUCHHOLZ RELAY:

Buchholz is used in a transformer to detect any internal fault with in a transformer, placed in between the transformer tank and the oil conservator, and this relay is connected to alarm circuit, to alert the operating personnel to take necessary action against the fault. It is a gas actuated relay. There are two elements upper element and lower element consists of mercury type switch. The circuit below is the basic circuit of

buchholz relay.

3.3.4 DIFFERENTIAL RELAY:

This type of relay operates when the phase differ or there is difference in quantity ratio of two or more similar electrical quantities. It gives sufficient protection to transformer internal fault.

Except these the following relays are also used in the sub-station as auxiliary relay because they sense condition from the main relay(e.g. over current relay, earth fault relay etc.)and do a specific work. 86or 186 relays are used as Tripping Relays

Instantaneous time relay in this type of relay no intentional delay is provided. The relay contact are immediately closed after the current in the relay coil exceeds the minimum calibrated value.

3.4 METERING INSTRUMENT

For visually inspecting electrical quantity there must be some metering instruments in the system. In the training we have the knowledge about various metering instrument as stated below:

VOLTMETER:- The voltmeter are used in measuring line volt, and connected in parallel with the line whose voltages are to be measured. For high or extra high line volt the meter are connected with secondary of P.T. circuit.

AMMETER:- These are used for measuring current in the system. These are connected with secondary(Metering winding) of C.T.

WATTMETER:- It is implemented to measure electrical power flowing through the circuit.

WATTHOUR METER :- For measuring electrical energy supplied by the system.

TRIVECTOR METER :- This meter measures reactive KVAh, KVA and KWh individually. Actually it consists of three meter all together with a special summator mounted between them. All the meter drive the summator through a complicated gearing system.

MAXPRINT:- It prints the maximum demand of any circuit in kva within a certain period of time (Suppose 15 or 30 minutes).

3.5 INSULATOR

As a sub-station delivers huge amount of power at a high or extra high voltage so there must need supports to current carriers to confine the current to conductors. This is achieved by insulator, which are most commonly made of porcelain. There are several type of insulators e.g. pin type. suspension type, strain type, post insulators. These are

used depending upon service requirements.post insulators are used to hold bus-bar, circuit breaker. Strain type insulator are used to provide the tension of the conductor at the dead end. On 132KV line nine discs are used in series by metal links. The insulator are glazy smooth enough to prevent deposition of dust, and ultimately for preventing the leakage of current and corona.

3.6 CAPACITOR BANK:

By using capacitor bank, We improve the power factor & also get some extra amount of energy. Like: at 38KV 14.4 MVAR & at 33KV 10.8MVAR. There are 36- capacitor bank.

APPARENT POWER AT FULL LOAD

10 100MVA

REACTIVE POWER60MVA 50

80MW 86.60MW

10MVAR TRUE POWER THROUGH CAPACITOR BANK

Power factor, cos Q=0.8; Q=36.87, After capacitor bank is in the system with full load,60MVAR decrease, if 10MVAR reactive power discharge through the capacitor bank (in the opp. directional) . & the voltage will increase. So now power factor :0.866. Here P.F improve =(86.60-80)MW=6.60MW

CAPACITOR BANK

3.7 BUS-BAR

When a number of feeders operating at the same voltage have to be directly connected electrically, bus-bar is used as common electrical component. These are basically copper or aluminium rods. They may also be made of A.C.S.R. type conductor (Maker-Dog, Mooz, Panther). In 132Kv side there are two bus-bar arrangements one main bus and the other transfer bus (One is at a time operated). In 33kv side two bus , bus A and bus B are operated parallel. They are connected by bus-coupler for protection and continued purposes.

3.8 BUS-COUPLER

It is not a device or equipment but it is very necessary arrangement of power system by which it could connect two separate bus bar without any interruption in the system service. In duplicate bus bar system once at a time one bus in operation and other is at rest. So whenever there need to repair the used bus bar then by this bus coupler arrangement the service can be continued without power interruption. Here in 132KV side two bus bar are connected with the bus coupler arrangement.

It is essentially consist of C.B., C.T. and Isolator switch and a P.T. when the power transferred from transfer bus. All protection of feeder of bus is obtained by this arrangement.

3.9 WAVE TRAP

Wave trap is an instrument using for tripping of the wave. The function of this trap is that it traps the unwanted waves. Its function is of trapping wave. Its shape is like a drum. It is connected to the main incoming feeder so that it can trap the waves which may be dangerous to the instruments here in the substation.

Low pass filter when power frequency currents are passed to switch yard and high frequency signals are blocked. Line Isolator with E.B. To isolate the line from Sub Station and earth, it under shut down.

3.10 CONDUCTOR

Conductor is the most essential part of a transmission or distribution system for carrying power from one place to another place. The Sub-station buses can be of the following types-

a) Rigid buses of solid conductor or tube bus b) Strain buses

As the cost of copper is very high and it is not so available so most conductor are made from aluminium. In the transmission line A.C.S.R (Aluminium Conductor Steel Reinforce) type conductor are used to give sufficient tension. In 33kv transmission or in the sub-station AAC (Aluminium Conductor) are used.

3.11 CONTROL-CABLE AND CONDUIT SYSTEM

The modern power complex has made it almost necessary to provide automatic operation interlocks. So the control cable and conduits are necessary for affecting such automatic control. The control system generally at 110V, 220V or 250V (DC) and the cable used is a multi conductor cable.

These conductor are generally placed in the ducts to run from control room to the junction boxes or where it is needed

3.12 BATTERY ROOM

For control of equipment and operation of relay etc. D.C. supply voltage is necessary. There are a no. of series connected plate type lead acid battery of EXIDE,INDIA Make. The system is provided with a battery charger system from a low voltage A.C. supply which is situated in a room is known as Battery room, which is a heart of the sub-station. three types of battery are used in this substation. They are-

1) Station battery: No of cell-110 Total Battery voltage-110*2=220v D.C.Total capacity- 125Ah YKP11EXIDE MAKE

2) P.L.C.C Battery :No of cell-24Total Battery voltage-24*2=48v DCTotal capacity-75Ah YKP7EXIDE MAKE

3) Gear Room Battery: No of cell:15Total Battery voltage-15*2=30v DCCapacity=40Ah YAMP=11EXIDE MAKE

4) Battery acid- Normal Sp. Gr. 1210 and Conduction sp. Gr.- 1180

3.13 GEAR BOX

It parts are- i) Spout, ii) U-connect, iii) oil tank, iv) Tripping coil, v) Operating mechanism

3.14 CONTROL ROOM

The control panel and remote control system, switch gear, carrier current equipment etc. are created in a room called CONTROL ROOM. From this control room, operator performs all type of control operations , recording of like lead, maximum demand etc.

3.15 TRANSFORMER

In a sub-station transformer are generally used to step down the high voltage from the transmission line to distribution line. For handling a large amount of power oftenly used transformer are known as power transformer.

3.15.1 TRANSMISSION PURPOSE

i) Here two transformer are used to step down the 132KV voltage to 33KV(one of 50 MVA and one of 31.5 MVA).The two transformer are operated in parallel. these transformer are cooled by air force oil natural method. These are star/delta type.

One example is given below

Transformer 1 Transformer 2

Oil(0c) Winding(0c) Oil(0c) Winding(0c)

51 66 55 72

ii)There are two earthing transformer (33/.4KV) which also used for station lightning purpose, these are connected with Bus A and Bus B each of 100KVA and star/star winding. It is used for protection purpose.

iii) Two railway transformer of 132/25KV of 12.5MVA and 10MVA transmit power to south- eastern railway.

iv) Three transformers are used to transmit power at 11KV from 33KV bus bar two of 6.3 MVA and one of 5 MVA.

v) One 33/0.4KV for lighting station quarter.

Actually these transformer operated at no-load condition in the secondary side. But in practice it is not possible.

3.15.2 MAINTANANCE PURPOSE

i) The transformers servicing the transmission purpose of the sub-station are needed to maintain properly and frequently.

ii) Main Accessories:-

a) Radiators :- Transformer are generally feeded with detachable radiators consisting of a series of circular or elliptical tubes welded at their top and bottom into header. the main purpose of radiators is to provide increased cooling surface for circulating oil by increasing the surface area of the tank.

b) Conservators :- Conservators are feeded on the top of the transformer in one side. The main purpose is to accommodate expanded oil due to heat.

c)Breather:- Breather is used to dry the air that enters the transformer as the volume of the oil decreases because of the fall in temperature. Silica gel crystals( calcium chloride) are used for this purpose. It shall always be ensure that the bottom hole of the breather remains open.

d) Bushings:- Bushings are provided with a transformer for entry of high voltage and exit of low voltage terminal and vice versa.66KV bushings are of generally oil filled

condenser type,33KV are of porcelain oil filled type and 11KV bushings are of porcelain plain shade type.

e) Tap changer:- There are three types of tap changer a) off circuit b) off load

c) on load (OLTC)

f ) Cooling:- The normal cooling is not sufficient as MVA rating and loading of the transformer increases. In WBSEB specification we are employing the type of cooling

a) oil natural and air natural (ONAN)b) oil natural and air forced (ONAF)c) oil directed and air forced (ODAF)

ONAN rating shall be about 50%,ONAF is about 75% and ODAF is about 100% of the rated capacity without exceeding the temperature limits.

iii) Cause of failure

i)Internal Factor:-

a)High temperature b)Design of over load capacity

ii) External Factor a)Over Loading b)Inadequate Protection c) Improper Maintainaces d) Social Problem

iv) Transformer Protection :- Successful effective operation of power supply system largely on effective protection of transformer as the replacement against each failureis not only costly but time sharing. Following protections are normally used:

a) Buchholtz Relay protectionb) Oil surge relay protectionc) Earth fault relay protectiond) Restricted E/F protectione) Over current protectionf) Differential protectiong) High Temperature protectionh) Low oil level protectioni) Over Fluxing protection

The following is the characteristic of insulating oil to be obtained (permissible limit):

Characteristics

Equipment Voltage

BeforeENERGISATIONOf new transformer Using new oil

When the TransformerIs in service

Electric strength

Below 72.5 KV 40KV rms (min) 30KV rms (min)

72.5KV and less than 145 KV

50KV rms (min) 40KV rms (min)

145KV and above 60KV rms (min) 50KV rms (min)

Water content

Below 72.5 KV 25 ppm (max) 35 ppm (max)

72.5KV and less than 145 KV

20 ppm (max) 25 ppm (max)

145KV and above 15 ppm (max) 25 ppm (max)

Specific resistor (resistivity) at 200c

All Voltage 1x10^12 Ohm-cm (min) 0.1x10^12 Ohm-cm (min)

DDP (tan-delta) at 900c

All Voltage 0.05 (max) 0.2 (max)

Total acid All Voltage 0.03 (max) 0.5 (max)

50 MVA

Indian standard is 2026

MVA- 50

Frequency-50Hz

Phase-3

Type of cooling ONAN ONAF OFAF

Rating HV (MVA) 30 40 50

Rating LV (MVA 30 40 50

No-load Voltage HV (KV) 132

No-load Voltage LV (KV) 33

Line Current HV(Amps)

131.37 175.16 218.95

Line Current LV(Amps)

528.48 700.65 875.81

%Impedance- 12.5% +/- 15 to 1/………….

Connection Symbol- Ynd1

Division- JHANSI

INSULATION LEVEL

HV 550kVP

LV 170kVP

HV 230KV r.m.s

LV 70 KV r.m.s

TRANSFORMER

Maker’s sl. No- 2012602

Electrical Specification no.- 625724

Year of Manufacture -1999

Diagram Drawing no- 14561950385

O.G.A Drawing no.- 04560050164

Weight of core and Winding (kg)- 401800

Customer – WBSEB Calcutta

Purchase Order – P&S/P- 10/98(PC-11)/LTD/244PS

NO-LOAD TAP CHANGER

Sl. No- 5002394 1999

Type M III 330 60LC 10103 rad

4.8 ohms

MA7 3495 4200173

415V 50Hz 1.1KW

110V 50HzPOT. 1000ohms

158468: 1977 IEC 214:1989

Tapposition

Leads joined HV Terminal

1U,1W,1V

LV Terminal

2U,2W,2V

Percentage

No-loadVoltage

KV

CurrentAmps

No-loadVoltage

KV

CurrentAmps

1(Max) (2-12),(3-4) 145.24 199.20 12.60

2

3

4

5

6

7

8

9A

(2-11),(3-4)

(2-10),(3-4)

(2-9),(3-4)

(2-8),(3-4)

(2-7),(3-4)

(2-6),(3-4)

(2-5),(3-4)

(2-4),(3-4)

143.35

141.9

140.25

138.6

136.95

133.30

133.65

132

201.34

203.68

206.07

208.53

211.04

213.61

216.35

218.95

9B (3-4)(3-12)(2-3) 132 218.95 33 875.81 11.83

9C

10

11

12

13

14

15

16

(2-12),(3-12)

(2-11),(3-12)

(2-10),(3-12)

(2-9),(3-12)

(2-8),(3-12)

(2-7),(3-12)

(2-6),(3-12)

(2-5),(3-12)

132

130.35

128.7

127.05

125.4

123.75

122.1

120.45

218.95

221.72

224.57

227.48

230.48

233.55

236.71

239.95

17(Min) (2-4),(3-12) 118.8 243.28 11.57

31.5 MVA

NAME PLATE :

TRANSFORMER

TO INDIAN STANDARD 2026-1962

MVA 31.5 VECTOR SYMBOLS Yd1 FREQUENCY 50Hz

KV (no load) HV 132 LV 33

AMPERES HV 138 LV 532

PHASE HV 3 LV 3

IMPEDANCE VOLT AT 750C ON 31.5 MVA BASE 11.68%

TYPE OF COOLING ON/OB ON RATING 60%

GUAURANTEED MAXIUM RISE IN OIL 450C OF WDG,BY RESISTANCE 550C

BIL HV/LV- 550/170KVP

Maker= Crompton greaves Limited ( Bombay )

OIL QUANTITY- TRANSFORMER (TOTAL) 21500LITERS 18.70TONNE

COLING PLANT 2470LITERS 2.15 TONNE

OLTC 1580 LITERS 1.37 TONNE

WEIGHTS: CORE &WEIGHT 31.80TONNES

COMPLETE TRANSFORMER

INCLUDING OIL 67.00 TONNES

OLTC WITH OIL 7.10TONNES

TRANSPORT WITH OIL (HEAVIES 50TONNES

PACKAGE)

DIAGRAM DRG.NO T62B797H

MAKER SERIAL NO 24517

YEAR OF MANUFACTURE 1984

SWITCHPOSITION

NO

HV VOLTS SWITCH CONNECTS LEAD NOS

1 145200 N-1

2 143550 N-2

3 141900 N-3

4 140250 N-4

5 138600 N-5

6 136950 N-6

7 135300 N-7

8 133650 N-8

9 132000 N-9

10 130350 N-10

11 128700 N-11

12 127050 N-12

13 125400 N-13

14 123750 N-14

15 122100 N-15

16 120450 N-16

17 118800 N-17

VECTOR DIAGRAM

NOTE

1.TAPPINGS CONNECTED TO 3 PHASE ON LOAD TAP CHANGER TYPE F 317-66 WHICH IS SUITABLE FOR POWER FLOW FROM 132KV SIDE TO 33KV SIDE ONLY.

2. WTI CT RATIO : 138/2.6, 2.7, 2.9A CONNECT TERMINALS S1 AND S3

10 MVA

Transformer to Indian std – 2026-1962

MVA – 10

Frequency- 50Hz

KV (no-load) – HV -132 LV-26.85

HV-75.7 LV-372.5

Phase impedance voltage at 750c -10.76%

Type of cooling –oil natural (ON)

Resistance- 500c

Bil HV/LV-550/170KVP

Oil quantity: Transformer (total)-9900 lts 8.66tones

Cooling plant- 1670lts 1.46tones

Weights- Core and Windings- 11.70tones

Transformer (including oil) – 30.20 tones

Transport with oil cheaviest package – 24 tones

Diagram no- T62b353q

Maker’s sl.no – 23733

Year of manufacture-1974

Customer’s reference-

Switch position

no

HV volts Switch connects Lead no

1

2

3

4

5

6

7

8

9

138600

135300

132000

128700

125400

122100

118800

115500

112200

(11-10),(12-13)

(11-9),(12-14)

(11-8),(12-15)

(11-7),(12-16)

(11-6),(12-17)

(11-5),(12-18)

(11-4),(12-19)

(11-3),(12-20)

(11-2),(12-21)

6.3 MVA

Standard is 2026

Maker’s sl. No- 096/98

KVA -6300

Type of cooling- ONAN

Frequency- 50Hz

Impedance voltage -6039X

Vector group ref.- DYN11

Volts at no –loads- HV-70KV

LV-28KV

Total weight of transformer (kg)- 13620

Total weight of core and winding (kg)- 7120

Weight of oil (kg)- 2680

Volume of oil (lt) -3100

Year of manufacture – 1998

Customer reference : P&S/P 13/96/1/R&A/R2/SP4 DT.7/498

Property of – WBSEB

Max. guaranteed temp. rise oil -800c winding 550c

OFF circuit tap changer No-load voltage Variation of HV

volts

Sw position connection HV LV

1

2

3

4

5

6

7

7-6

6-8

8-5

5-9

9-4

4-10

10-3

34650

33825

33000

32175

31350

30525

29700

11000

11000

11000

11000

11000

11000

11000

+5

+2.5

Normal

-2.5

-5

-7.5

-10

5 MVA

General Electric Company of India (G.E.C)

KVA-5000

Type of cooling – ONAN

Frequency- 50Hz

Impedance voltage – 6.8%

Vector group ref - HV -33000

LV- 11000

Phase – HV- 3

LV- 3

Amperes- HV- 87.5

LV-262.5

Insulation level – HV -70KV

LV- 28KV

Transport mass (kg)-9000

Weight of oil (kg)- 2010

Volume of oil (Lt.)- 2320

Total mass (kg)- 11200

Diagram DRS no.- G80445

Temp. Rise in oil- 450c

Winding- 550c

Year of manufacture -1983

Maker’s ref No- CT-4378

SL. No.- 214098/7

Property of- WBSEB

3.16 POLES

The supporting structure for overhead line conductor are various types of poles and

towers called line supports. In general the line supports should have the following properties:-

i) High mechanical strength to withstand the weight of conductor and wind loads

ii) Light in weight without the loss in mechanical strength

iii) Cheap in cost and economical to maintain

iv) Longer life

v) Easy accessibility of conductors of maintenance.

In this SUB-STATION following tower are used

a) 132 KV single circuit (s/c):

Type

A(a)

Upto 20 Angle

B/C (b)

Upto 300 angle

D(c)

Above 300c angle

Height (m) 26 29 32 25.7 28.7 31.7 22.5 25.5 28.5

Length of base

(m) 4.5 5.2 5.9 6.3 7.34 8.4 5.6 6.6 7.6

b) 132KV double circuit (s/c):

Type

A(a)

Upto 20 Angle

B/C (b)

Upto 300 angle

D(c)

Above 300c angle

Height (m) 26 29 32 25.7 28.7 31.7 26.7 29.7 32.7

Length of base

(m) 4.5 5.2 5.9 6.3 7.34 8.4 7.4 8.7 10.0

4.POWER LOAD CURRENT COMMUTATOR

4.1 Principal of operation

Because of their low attenuation in the carrier frequency range between 20

and 500KHz, EHV transmission lines are a good means of communicating information over

medium to long distances (20 to100km,100 to 500 km respectively)

By installing appropriate coupling device and line traps in power stations

and Sub-station communication channel can be provided.

Power line carriers is used in almost all the countries of the world to

transfer information via HV transmission lines and has become an important instrument for the

management and safety of electrical power system. Multiple uses of PLC channel for speech,

data, and protection have been become widely established.

4.2 General Arrangement of different sub-station of PLCC system

Blue phase of the three-phase transmission line phases through the wave trap

and is connected to the main BUS or Transfer BUS via line side C.T, Circuit Breaker, Isolator

etc.main function of the Wave Trap is to allow 50Hz frequency through it and block the other

frequency level signals.

Another jumper from Blue phase before the Wave Trap is connected at the top

of the CVT (Primary side) so that frequencies other than 50Hz at 132KV voltage level can pass

through it. Other side (Primary connection) of CVT is grounded.

From CVT secondary terminals signal goes to Line Matching Unit (LMU) at

110V level for impedance matching purpose. Output of CVT is also used for synchronization

purpose.

From LMU signal goes to PLCC panel (Carrier Panel) for modulation or

demodulation purpose through co-axial cable.

Several PLCC panels associated with different transmission lines are

connected to a common Electronic Private Automatic Branch Exchange (EPABX).End users

are connected with EPABX by telephone sets.

Communication is possible in Duplex mode.

Even data communication is possible .

4.3 The Technology of PLCC

Power line communication (PLC) is a wire line method of communication that uses the existing electrical power transmission lines. The carrier can communication voice and data by superimposing an analog signal over the standard 50Hz alternating current . traditionally electrical units use low speed power line carrier circuit for control of sub- station, voice communication and protection of High Voltage Transmission Line (HVTL). More recently, high speed data transmission has been developed using the lower voltage transmission lines used for power distribution. A short range from of power line carrier is used for home automation and intercoms. The technology of PLCC is of two types as follows:-

a) Indoor:- These devices operated by injecting a carrier wave of between 20 to 200 KHz into household wiring at the transmitter.

b) Outdoor :- Frequencies used are in the range of 30 to300 KHz with transmitter power level up to hundreds of watts.

4.4 PLCC Features

a) system features:-

1) Store program control 2) 48 subscribes/16 trunks 3) Non-blocking switching network 4) Modular in construction 5) Flexible directory scheme 6) Direct outward dialing 7) Priority 8) Pulse/DTMF dialing 9) Paging(with customer provided Amplifier system) 10) Conference 11) Diagnostics 12) Music on hold b) Extension features:-

1) Local call 2) Call transfer 3) Call consult 4) Automatic call back 5) Conference 6) Follow me 7) Call pick-up

8) Paging(with customer provided Amplifier system) 9) Appointment 10) Do-not-disturb 11) Call forward

5. ACTIVITES OF THE SUB-STATION

OPERATION : The sub-station receives power at 132kv from kolaghat thermal power station, three phases, double circuit. And then it delivers power at33KV.for this the receive voltage is stepped down by two transformer ,which are operating in parallel. The main activities of the sub-station are to operate the equipment present in the sub-station and to have a proper co-ordination among mentioned sub-station.for this purpose, control room can keep the circuits from the distance whenever the situation impels. It’s all concerned with control room, have the responsibility to monitor the situation allover the day and night. for further planning datas are kept in a black register.

MAINTENANCE:- The sub-station has a large number of equipment .the sub-station member bear the responsibility of maintaining the equipment properly and repair them whenever necessary The circuit breaker is the most important equipment,which makes and breaks the circuit. So they are sometime badly damage. It is the routine work to do the maintenance operation once in a weak.

BREAKER PORTION:- The minimum oil breaker consists of a box frame mechanism over which three breaker poles are mounted. Each pole of the breaker is provided with an oil level indicator, a breather and a gas discharge valve from venting the gases formed during the current interruption. An extinguishing chamber of a contraction type is build into the interrupting chamber insulator. The fixed contact is tripped with heat resistance contact metal and is provided with an arcing ring. The base frame contains the operating shaft operating spring, starting buffers and oil dash pot.

BREAKER MAINTENANCE :- Necessary shut down and permit to work card should be issued to the competent person in prescribe from by the competent authority.Caution:- 1) The circuit breaker will have to be completely insulated from the supply and to be earthed 2) Isolator are to be cut off from either side of breaker 3) AC/DC control selector switch is to be shut off from remote end to local control circuit and fuses are to be taken out.

CIRCUIT BREAKER CONTACT: Circuit breaker which have in closed position for an extended period get a coating on the current transmitting surfaces on the contacts which increases the resistance in the main circuit. this coating cab be easily removed by operating the circuit breaker a few times in the unloaded condition. This operation is also favorable for the parts of the mechanism incorporated and contributed to a high degree of preparedness and at the same time is to check on operating end signal devices.

CONCLUSION

During my final year of diploma course through this ‘vocational Training’ period I gate some working experience and also some practical knowledge. Though the training is of very short period, I’m very sure that this short time experience will help me in future.

BIBLIOGRAPHY

Principles of Power System------- V.K.Mehta, Rohit Mehta Power System Engineering--------- Nagrath & Kothary, TMH

www.wikipedia.org

1.SUB-STATION

The economics of generation of electrical energy and the huge demand for power in the modern times require creation of bigger power powerhouse. The powerhouses may be far away from the load centers. So the transformer network is inevitable. In between the powerhouse and ultimate consumer, a number of transformation and switching station are to be created. These are generally known as sub-stations

1.1 Types of Sub-station

1.1.1 Service

a) Static (Alternating)

b) Converting (A.C to D.C)

1.1.2 Purpose

a) Step-up Sub-station

b) Primary grid Sub-station

c) Secondary grid Sub-station (Transmission & Step down)

d) Distribution Sub-station

e) Industrial Sub-station

f) Mobile Sub-station

1.1.3 Control

a) Manual

b) Automatic

c) Supervisory

1.1.4 MOUNTING:

a) Indoor Sub-station

b) Outdoor Sub-station

c) Underground Sub-station

d) Pole mounted Sub-station