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PROTECTION OFPROTECTION OF

TRANSFORMERSTRANSFORMERS

Presented byPresented by

AMAR NAYYARAMAR NAYYAR

FINAL YEAR ELECTRICALSFINAL YEAR ELECTRICALS

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WHAT IS A TRANSFORMER?WHAT IS A TRANSFORMER?

TRANSFORMER IS ATRANSFORMER IS ASTATIC DEVICE WHICHSTATIC DEVICE WHICH

TRANSFORMS A.C.TRANSFORMS A.C.

ELECTRICAL POWERELECTRICAL POWERFROM ONE VOLTAGEFROM ONE VOLTAGE

TO ANOTHERTO ANOTHERVOLTAGE KEEPINGVOLTAGE KEEPINGTHE FREQUENCY SAMETHE FREQUENCY SAME

BY ELECTROMAGNETICBY ELECTROMAGNETICINDUCTION.INDUCTION.

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TYPES OF TRANSFORMERTYPES OF TRANSFORMER

BY APPLICATIONBY APPLICATION 1. DISTRIBUTION TRANSFORMER1. DISTRIBUTION TRANSFORMER 2.POWER TRANSFORMER2.POWER TRANSFORMER

3.CURRENT TRANSFORMER3.CURRENT TRANSFORMER 4.POTENTIAL TRANSFORMER4.POTENTIAL TRANSFORMER

5.FURNACE TRANSFORMER5.FURNACE TRANSFORMER

6.BOOSTER TRANSFORMER6.BOOSTER TRANSFORMER 7.RECTIFIER TRANSFORMER7.RECTIFIER TRANSFORMER 8.LOCOMOTIVE TRANSFORMER8.LOCOMOTIVE TRANSFORMER

9.MINING TRANSFORMER9.MINING TRANSFORMER 10.PHASE SHIFTING TRANSFORMER10.PHASE SHIFTING TRANSFORMER

11.WELDING TRANSFORMER11.WELDING TRANSFORMER 1

2.HIGH VOLTAGE TESTING/SC TESTING TRF.12.HIGH VOLTAGE TESTING/SC TESTING TRF.

13.GROUNDING TRANSFORMERS13.GROUNDING TRANSFORMERS 14.CONVERTER TRANSFORMER14.CONVERTER TRANSFORMER

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DISTRIBUTION TRANSFORMERDISTRIBUTION TRANSFORMER

TRANSFORMER WHICH IS USED FORTRANSFORMER WHICH IS USED FOR

THE PURPOSE OF DISTRIBUTION OFTHE PURPOSE OF DISTRIBUTION OF

POWER.POWER. 11KV/433V is the standard voltage rating.11KV/433V is the standard voltage rating.

STANDARD KVA ratings areSTANDARD KVA ratings are

25,63,100

,160,200

,250,315,4

00,500

,630,75

0,25,63,

100,160,200

,250,315,4

00,500

,630,75

0,

1000 , 1250,1500,2000,2500 KVA.1000 , 1250,1500,2000,2500 KVA.

ISIS--2026 is the NATIONAL I S STANDARD.2026 is the NATIONAL I S STANDARD.

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MAIN FEATURESMAIN FEATURES

OUTDOOR,OIL COOLED, 3 PHASE,50HZOUTDOOR,OIL COOLED, 3 PHASE,50HZ

PRIMARY IS DELTA CONNECTED ANDPRIMARY IS DELTA CONNECTED AND

SECONDARY IS STAR CONNECTED.SECONDARY IS STAR CONNECTED. NATURALY COOLED (ONAN TYPE).NATURALY COOLED (ONAN TYPE).

AMONGST ALL THE TYPES OFAMONGST ALL THE TYPES OF

TRANSFORMERS THIS IS THE MOSTTRANSFORMERS THIS IS THE MOSTREQUIRED AND MOST USED TYPE.REQUIRED AND MOST USED TYPE.

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PARTS OF TRANSFORMERPARTS OF TRANSFORMER

MAIN TANKMAIN TANK RADIATORSRADIATORS CONSERVATORCONSERVATOR EXPLOSION VENTEXPLOSION VENT

LIFTING LUGSLIFTING LUGS AIR RELEASE PLUGAIR RELEASE PLUG OIL LEVEL INDICATOROIL LEVEL INDICATOR TAP CHANGERTAP CHANGER WHEELSWHEELS HV/LV BUSHINGSHV/LV BUSHINGS

FILTER VALVESFILTER VALVES OIL FILLING PLUGOIL FILLING PLUG DRAIN PLUGDRAIN PLUG CABLE BOXCABLE BOX

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TESTING OF TRANSFORMERTESTING OF TRANSFORMER

TESTING IS CARRIED OUT AS PER ISTESTING IS CARRIED OUT AS PER IS--2026.2026. ROUTINE , TYPE TESTS & SPECIAL TESTSROUTINE , TYPE TESTS & SPECIAL TESTS

ROUTINE TESTS ( TO BE CARRIED OUT ON EACH JOB)ROUTINE TESTS ( TO BE CARRIED OUT ON EACH JOB)

1.Measurement of winding resistance1.Measurement of winding resistance 2.Measurement of insulation resistance2.Measurement of insulation resistance 3.Seperate source voltage withstand test (High Voltage tests on HV & LV)3.Seperate source voltage withstand test (High Voltage tests on HV & LV) 4.Induced Over voltage Withstand test (DVDF test)4.Induced Over voltage Withstand test (DVDF test)

5.Measurement of voltage ratio5.Measurement of voltage ratio 6.Measurement of NO LOAD LOSS & current.6.Measurement of NO LOAD LOSS & current.

7.Measurement of LOAD LOSS & IMPEDENCE.(EFFICIENCY & REGULATION)7.Measurement of LOAD LOSS & IMPEDENCE.(EFFICIENCY & REGULATION)

8.Vector Group Verification8.Vector Group Verification 9.Oil BDV test.9.Oil BDV test. 10.Tests on OLTC (if Attached)10.Tests on OLTC (if Attached)

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TYPE TESTSTYPE TESTS

THESE TESTS ARE CARRIED OUTTHESE TESTS ARE CARRIED OUT

ONLY ON ONE TRANSFORMER OFONLY ON ONE TRANSFORMER OFTHE LOT.THE LOT.

All routine testsAll routine tests

Additionally following tests are included inAdditionally following tests are included in

type teststype tests

1.1. Lightening Impulse test.Lightening Impulse test.

2.2. Temperature rise testTemperature rise test

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SPECIAL TESTSSPECIAL TESTS

Additional Impulse testAdditional Impulse test

Short circuit testShort circuit test

Measurement of zero Phase sequenceMeasurement of zero Phase sequenceImpedance test.Impedance test.

Measurement of acoustic noise level.Measurement of acoustic noise level.

Measurement of harmonics of the no loadMeasurement of harmonics of the no loadcurrent.current.

Magnetic balance test.Magnetic balance test.

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ROUTINE TESTSROUTINE TESTS

1.Measurement of winding resistance1.Measurement of winding resistance

This test measures the resistance of the HV & LVThis test measures the resistance of the HV & LV

winding. The values of resistance should bewinding. The values of resistance should bebalance for all three phases and should matchbalance for all three phases and should matchthe designed values.the designed values.

Equipment used : Digital resistance meter.Equipment used : Digital resistance meter.

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ROUTINE TESTSROUTINE TESTS

2.Measurement of insulation resistance2.Measurement of insulation resistance

Measures the insulation resistance of HV & LVMeasures the insulation resistance of HV & LV

windings with respect to earth (body) andwindings with respect to earth (body) andbetween LV & HV winding.between LV & HV winding.

INSULATION TESTER OR MEGGER ISINSULATION TESTER OR MEGGER IS

USED.USED.

Recommended Values areRecommended Values are

2000Mohms for HV & 500 Mohms for LV.2000Mohms for HV & 500 Mohms for LV.

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ROUTINE TESTSROUTINE TESTS

3.Seperate source voltage withstand test (High Voltage tests on3.Seperate source voltage withstand test (High Voltage tests onHV & LV)HV & LV)-- This test checks the insulation property betweenThis test checks the insulation property betweenPrimary to earth, Secondary to earth and between Primary &Primary to earth, Secondary to earth and between Primary &Secondary.Secondary.

HV high voltage test : LV winding connected together and earthed.HV high voltage test : LV winding connected together and earthed.HV winding connected together and given 28 KV ( for 11KVHV winding connected together and given 28 KV ( for 11KVtransformer) for 1 minute.transformer) for 1 minute.

LV high Voltage test : HV winding connected together and earthed.LV high Voltage test : HV winding connected together and earthed.LV winding connected together and given 3 KV for 1 minute.LV winding connected together and given 3 KV for 1 minute.

Equipment used : High Voltage tester (100KV & 3KV)Equipment used : High Voltage tester (100KV & 3KV)

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ROUTINE TESTSROUTINE TESTS

4.Induced Over voltage Withstand test (DVDF test)4.Induced Over voltage Withstand test (DVDF test)--This test checks the inter turn insulation.This test checks the inter turn insulation.

For a 11KV/433V transformer,866 Volts are applied atFor a 11KV/433V transformer,866 Volts are applied atthe 433V winding with the help of a Generator for 1the 433V winding with the help of a Generator for 1minute. This induces 22KV on 11KV side. Theminute. This induces 22KV on 11KV side. Thefrequency of the 866V supply is also increased tofrequency of the 866V supply is also increased to100HZ.100HZ.

Equipment used : MOTOR GENERATOR SETEquipment used : MOTOR GENERATOR SET

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ROUTINE TESTSROUTINE TESTS

5.Measurement of voltage ratio5.Measurement of voltage ratio

This test measures the voltage ratio as per the customersThis test measures the voltage ratio as per the customersrequirement.requirement.

V1/V2 = N1/N2V1/V2 = N1/N2

The voltage ratio is equal to the turns ratio in aThe voltage ratio is equal to the turns ratio in atransformer. Using this principle, the turns ratio istransformer. Using this principle, the turns ratio is

measured with the help of a turns ratio meter. If it ismeasured with the help of a turns ratio meter. If it iscorrect , then the voltage ratio is assumed to be correct.correct , then the voltage ratio is assumed to b