33/11 KV Sub Station Santosh S. Kamble J.E ALDC, Ambazari MSETCL, Nagpur

Schematic Power System Diagram

33 KV Bus P.T 11 KV 33/11 kv sub station LA ES ISO CT CB LA T/F CB CT

CLASSIFICATION OF SUBSTATION According to Design. 1.Indoor type Sub-station. (a) Pole mounted Sub-station. (b) Foundation mounted Sub-station. 2.Out door type Sub-station.

Main Equipments in 33 KV Sub-Station 1) Power transformer 1) Power transformer 2) Circuit breaker 2) Circuit breaker 3) Isolator 3) Isolator 4) Earthing switch 4) Earthing switch 5) lightning arrestor 5) lightning arrestor 6) Busbar 6) Busbar 7) Current transformer 7) Current transformer 8) Potential transformer 8) Potential transformer 9) Protective relay 9) Protective relay 10) DC battery set 10) DC battery set 11)Capacitor bank 11)Capacitor bank 12)Fire fighting system 12)Fire fighting system

1) Power transformer 1) Power transformer Transformer is used to step down the voltage from 33 kv voltage to 11kv voltage. Transformer is used to step down the voltage from 33 kv voltage to 11kv voltage. Generally 3.15 MVA, 5 MVA, 10 MVA 33/11kv, Δ / Y transformer are used in 33/11kv s/s. Generally 3.15 MVA, 5 MVA, 10 MVA 33/11kv, Δ / Y transformer are used in 33/11kv s/s.

33 / 11 KV Transformer

Transformers

Maintenance of Transformers Check Oil level in main tank & OLTC tank. Check Oil level in main tank & OLTC tank. Check the color of silica gel in breather ;it must be blue in color.if it is turned pink then recondition it or replace it. Check the color of silica gel in breather ;it must be blue in color.if it is turned pink then recondition it or replace it. Check On load Tap Changer Lower/Raise trail by Local & Remote. Check On load Tap Changer Lower/Raise trail by Local & Remote. Trip trail by draining oil in Buchholz relay Trip trail by draining oil in Buchholz relay

Maintenance of Transformers Check Earth resistance,provide watering arrangement for earthling pits. Check Earth resistance,provide watering arrangement for earthling pits. Tight all connections. Tight all connections. Check breakdown voltage of oil. Check breakdown voltage of oil. Clean the bushings. Clean the bushings. Attend the oil leakages Attend the oil leakages Note Temperature of Oil & leakage. Note Temperature of Oil & leakage.

Check cooling system & confirm fan control operation w.r.to temperature variation. Check cooling system & confirm fan control operation w.r.to temperature variation. Check IR values of the transformer Check IR values of the transformer

Power Transformer Specification 33/11 KV, Δ / Y, 3.15 MVA, 5 MVA, 10 MVA 33/11 KV, Δ / Y, 3.15 MVA, 5 MVA, 10 MVA

VARIOUS TYPES OF LOSSES IN TRANSFORMER Various types of losses. Iron & core losses. Hysterics loss. Eddy current loss. Copper losses.

TRANSFORMER OIL It’s mineral oil obtained by refine crude petroleum. It serves the following purpose. Provide additional insulation. Carries away the heat generated in the core & coils. Protects the paper from dirt & moisture.

TYPES OF INSTRUMENT TRANSFORMER CURRENT TRANSFORMER POTENTIAL TRANSFORMER

Current Transformer Current Transformer Current T/F is used for protection and metering purposes. Current T/F is used for protection and metering purposes. It steps down the current level of the line for following purposes. It steps down the current level of the line for following purposes. 1) Measurement : ammeter, kw meter, kwh meter, power factor meter 2) control and protection : current when exceeds the set value operates the relay which senses the faulty condition.

33 KV CT

CT specification / 5 A / 5 A / 5 A / 5 A / 5 A / 5 A / 5 A / 5 A

CT specificatons General particulars 11KV33KV Highest System voltage (H.S.V.) 12KV(r.m.s)36KV(r.m.s) Number of coreUpto 5 Output burdenUpto 60VA,0.8pf lagging Accuracy ClassFor Metering 0.2S,0.2,0.5S,0.5,1.0 & 3.00 For Protection 5P,10P,15P & PS

Potential Transformer (P.T) Potential Transformer (P.T) It steps down the voltage level of line for - 1) Measurement : voltmeter, frequency meter,kw meter, kwh meter,power factor meter 2) Control & protection : used in directional over current protection and under frequency relay operation (48.8 Hz, df/dt relay)

33 KV PT

PT Specifications For 33 KV :- 33 KV / 110 V/√3 For 33 KV :- 33 KV / 110 V/√3 For 11 KV :- 11 KV / 110 V/√3 For 11 KV :- 11 KV / 110 V/√3

PT specificatons General particulars 11KV33KV Highest System voltage (H.S.V.) 12KV(r.m.s)36KV(r.m.s) Output burdenUpto 200VA Accuracy ClassFor Metering 0.2,0.5,1.0 & 3.00 For Protection 3P,6P.

Circuit Breaker Circuit Breaker can switch automatically during normal and abnormal conditions. during faulty condition the fault is sensed by the relay and operates the circuit breaker to isolate the fault. Circuit Breaker can switch automatically during normal and abnormal conditions. during faulty condition the fault is sensed by the relay and operates the circuit breaker to isolate the fault. In 33kv substation generally vacuum circuit breaker are used where are quenching medium is vacuum

TYPES OF CIRCUIT BREAKER Low voltage air circuit breaker. Oil circuit breaker. Air blast circuit breaker. SF6 circuit breaker. Vacuum circuit breaker.

VCB specification 11 KV 33 KV Rated Voltage 12 KV 36 KV Normal Current 400 A 630 A S.C Breaking Current 8 & 12.5 KA 12.5 KA (750 MVA) DC Voltage 24 V

Method of arc extinction in circuit breaker High resistance interruption. (1) Arc lengthening. (2) Arc cooling. (3) Arc splitting. (4) Arc constraining. Low resistance interruption. (1) Cooling. (2) Gap lengthening. (3) Blast effect.

Advantage of Vacuum Circuit Breaker 1) no oil is required for are quenching 1) no oil is required for are quenching 2) least maintenance 2) least maintenance 3) compact size 3) compact size 4) light in weight 4) light in weight Maintenance of circuit breaker Maintenance of circuit breaker 1) close/trip through local/remote control 1) close/trip through local/remote control 2) trip trial through auto closer relay 2) trip trial through auto closer relay 4) oiling & greasing of moving parts 4) oiling & greasing of moving parts 5) vermin proofing 5) vermin proofing 6) heater healthy 6) heater healthy

Isolator Isolator Isolator is used to isolate the equipment. Isolator is used to isolate the equipment. Isolator is operate at no load. Isolator is operate at no load. Maintenance of isolator:- 1) oiling &greasing of moving parts. 2) check contact firmness. 3) check open / close trials. 4) Earthing switch.

AB Switch It is operated on No Load Only. It is operated on No Load Only. Rated Voltage :- 12 KV Rated Voltage :- 12 KV Normal Current :- 400 A Normal Current :- 400 A

Isolator Specification Rated Voltage :- 36 V Rated Voltage :- 36 V Normal Current :- 630 A Normal Current :- 630 A

Earthing switch Earthing switch discharges the voltage an deadline to earth. it is connected between line unit of isolator to earth. Earthing switch discharges the voltage an deadline to earth. it is connected between line unit of isolator to earth. NOTE: it there is breakdown at line then for measurement of resistance by megger do not close earth switch.

Lighting arrestor Lighting arrestor is used for lightning surge protection. Lighting arrestor is used for lightning surge protection. Lighting arrestor is used in line side as well as T/F HV & LV side. Lighting arrestor is used in line side as well as T/F HV & LV side.

11 KV Lightning Arrestor

Metal Oxide LA Specification 11 KV 33 KV Voltage Rating 9 KV 30 KV Normal Discharge Current 5 KA 10 KA

Busbar Busbar are conducting rod to which a number incoming and outgoing feeders are connected in 33kv S/S there are 33kv bus & 11kv bus. Busbar are conducting rod to which a number incoming and outgoing feeders are connected in 33kv S/S there are 33kv bus & 11kv bus. VARIOUS TYPES OF BUS BAR ARRANGE- MENT SYSTEM:- Single bus bar system used in D.C. and A.C. power station. Single bus bar system used in D.C. and A.C. power station. Single bus bar system with sectionalization. Single bus bar system with sectionalization. Ring bus bar system. Ring bus bar system. Duplicate bus bar system. Duplicate bus bar system.

FUSE.

DIFFERENT TYPES OF FUSES

FUSE. Copper. Silver.Tin Lead. TYPES OF MATERIAL USED IN FUSE WIRE:-

Rewireable fuse. Rewireable fuse. Cartridge type fuse. Cartridge type fuse. Drop out fuse. Drop out fuse. High capacity H.R.C. fuse. High capacity H.R.C. fuse. High voltage H.R.C. fuse. High voltage H.R.C. fuse. Types of Fuse element

FUSE. Rewireable fuse. Cartridge type fuse. Drop out fuse. High capacity H.R.C. fuse. High voltage H.R.C. fuse. TYPES OF FUSES:-

Drop Out Fuse Specification 11 KV, 50 HZ. 11 KV, 50 HZ. Rated Voltage :- 12 KV Rated Voltage :- 12 KV Rated Normal Current:- 100 A. Rated Normal Current:- 100 A.

TYPES OF M.C.B.

INTRODUCTION OF PROTECTION SCHEME DESIRED CHARECTERISTICS OF PROTECTION SYSTEM:- Characteristics of protection system. 1.Reliability 2.Sensitivity. 3.Selectivity. 4.Descrimination. 5.Speed. 6.Simplicity. 7.Economy.

Protective relay Protective relay FUNCTION OF PROTECTIVE RELAYS:- The relay is used to cut off the power supply, promptly to any element of power system which undergoes short –circuit it starts operating abnormally. The relay is used to cut off the power supply, promptly to any element of power system which undergoes short –circuit it starts operating abnormally.

Different Types of Relay Different Types of Relay:- Different Types of Relay:- 1.Solenoid type. 2.Attracted armature Type. 3.Electrodynemic Type. 4.Moving coil type. 5.Induction type.6.Thermal relay. 7.Earth fault relay.

MAIN FEATURES OF PROTECTIVE RELAY Main features of a good protective relay. 1.Reliability 2.Sensitivity. 3.Selectivity. 4.Quickness. 5.Non interference With future extension.

RELAY USED FOR TRANSFORMER PROTECTION 1) Differential Relay 2) Over Current Earth Fault Relay 3) Buchholz Relay

1) Differential relay This is the main protection provided to the transformer. This takes care of all the internal faults within the protection zone at this relay it from hv, ct to lv ct,it is also called as Differential zone. Fault lying within this zone are called as external fault or through fault. This is the main protection provided to the transformer. This takes care of all the internal faults within the protection zone at this relay it from hv, ct to lv ct,it is also called as Differential zone. Fault lying within this zone are called as external fault or through fault. Details of the relay Details of the relay transformer Differential protection relay transformer Differential protection relay percentage Bias type percentage Bias type suitable for 2 winding transformer,CTR-iA, suitable for 2 winding transformer,CTR-iA, aux 30v DC aux 30v DC operating current % operating current % Bias setting 20-30%, operating time less than msec for time setting contact 2 nos Bias setting 20-30%, operating time less than msec for time setting contact 2 nos

2) Over Current Earth Fault Relay over current earth fault protection is also called as back up protection. It two transformers are used in parallel than directional Over Current Earth fault relay should be used. over current earth fault protection is also called as back up protection. It two transformers are used in parallel than directional Over Current Earth fault relay should be used. These relay are provided on 33kv hv side of the transformer,11kv (lv) side of the transformer and on 11kv feeders. These relay are provided on 33kv hv side of the transformer,11kv (lv) side of the transformer and on 11kv feeders.

3) Buchholz Relay It is used to provide protection against internal faults in transformer. Incipient faults are due to the arcing in the oil because of the failure of the inter - lamination or core bolt insulation or poor electrical connection causing spark in the oil. These fault occurs the gas in the main tank rushes upwards and gets accumulated in the relay chamber. initially it initiates buchholz alarm it the fault persist then buchholz trip command is extended to the CB. It is used to provide protection against internal faults in transformer. Incipient faults are due to the arcing in the oil because of the failure of the inter - lamination or core bolt insulation or poor electrical connection causing spark in the oil. These fault occurs the gas in the main tank rushes upwards and gets accumulated in the relay chamber. initially it initiates buchholz alarm it the fault persist then buchholz trip command is extended to the CB.

DC battery set Generally for 33kv S/S Generally for 33kv S/S Auxiliary DC volt is 30 v DC, 15 nos of cells are used Auxiliary DC volt is 30 v DC, 15 nos of cells are used DC voltage supply is used for following control circuit DC voltage supply is used for following control circuit 1) Tripping circuit of CB 2) Closing circuit of CB 3) Alarm circuit, (buchholz alarm, winding temp alarm, trip alarm,DC fail alarm) 4) Semaphore indicator (indicators the close/open position of isobar and CB) 5) Breaker on/off indicates (indication bulbs are used ) 6) Trip circuit healthy indication (indication bulb is used )

Maintenance of DC battery Specific Gravity of electrolyte and amount of charged Specific Gravity of electrolyte and amount of charged Hydrometer :- it is the device used for measurement of specific gravity of electrolyte range is 1150 to Hydrometer :- it is the device used for measurement of specific gravity of electrolyte range is 1150 to Discharged Specific Gravity At 27 o C Below 1150

Capacitor bank Capacitor bank 3 ph Capacitor bank is used for improvement of power factor. It is normally connected to 11 kv bus. VCB is used for Capacitor bank switching. 3 ph Capacitor bank is used for improvement of power factor. It is normally connected to 11 kv bus. VCB is used for Capacitor bank switching. Normally capacitor banks are connected in star. Normally capacitor banks are connected in star.

Capacitor Bank Specification 12 KV, 1200 KVAr, 2400 KVAr, 3600 KVAr 12 KV, 1200 KVAr, 2400 KVAr, 3600 KVAr

Capacitor Bank

PF improvement The advantages of power factors improvement by Capacitor addition:- The advantages of power factors improvement by Capacitor addition:- a) Reactive component of the network is reduced and so also the total current in the system from the source end a) Reactive component of the network is reduced and so also the total current in the system from the source end b) I 2 R power losses are reduced in the system because of reduction in current b) I 2 R power losses are reduced in the system because of reduction in current c) voltage level at the load end is increased c) voltage level at the load end is increased

Cost Benefits of PF improvement Reduced kvA (maximum demand ) charges in utility bill. Reduced kvA (maximum demand ) charges in utility bill. Reduced distribution losses (kwh) within the plant network. Reduced distribution losses (kwh) within the plant network. Better voltage and improved performance of system. Better voltage and improved performance of system. A high power factor eliminates penalty charges imposed when operating with a low power factor. A high power factor eliminates penalty charges imposed when operating with a low power factor.

13) Fire fighting system 13) Fire fighting system Following fire extinguishing mediums are used :- 1) Iron buckets full of sand are kept ready. 1) Iron buckets full of sand are kept ready. 2) Carbon dioxide cylinders. 2) Carbon dioxide cylinders.

ISO AB ISO AB 3PH SUPPLY ISO AB RY B RY B R Y B R Y B R Y B POWER X’MER INCOMING BUSBAR OUTGOING BUSBAR