POWER TRANSFORMER

POWER TRANSFORMER PRESENTATIONBYHITESH KUMARMANAGER(T) PROTECTIONDELHI TRANSCO LIMITED11POWER TRANSFORMER B. Transformer Connections and Operation:PolarityEach of the two primary terminals of a transformer is alternately positive and negative with respect to the other, and the same thing is of course true with respect to the secondary terminals.Identification of Polarity is required for Parallel operation of the transformers and to get various vector groups.

Three phase transformer connectionsWindings can be connected to get various vector groups throughStar/Delta connections. A clock number is given to each connection. The commonconnection are: Yy0,Dd0, Yd1, Dy1, Yd5, Dy5, Yy6, Dd6, Yd11, Dy11

22POWER TRANSFORMER Transformer Connections and Operation:

Conditions for Parallel Operation:Same vector group (The same phase angle difference between the primary and secondary terminals). Same polaritySame phase sequenceSame voltage ratioSame per unit impedanceSame ratio of equivalent leakage reactance to equivalent resistance

33POWER TRANSFORMER Transformer Connections and Operation:

44POWER TRANSFORMER Transformer Connections and Operation:Conditions for Parallel Operation:Voltage ratio is Equal.No load voltage of two transformers are equal Ea = Eb B)Primary leakage impedance drop due to Ie is equal. Zea = Zeb(Xea/ Rea = Xeb/Reb) No circulating current flows between the two transformers.

55POWER TRANSFORMER Transformer Connections and Operation:Conditions for Parallel Operation:Voltage ratio is equal.No circulating current flows.

Ea = Eb I = Ia + IbIa Xea = Ib XebVIa Rea = Ib Reb

2Ia Zea = Ib Zeb22Ea IV Zea Ia Load Eb Zeb Ib Ea = Ia Zea + V

Eb = Ib Zeb + VIbIa66POWER TRANSFORMER Transformer Connections and Operation:Conditions for Parallel Operation:Voltage ratio is different, Ea > Eb, Xea/ Rea = Xeb/Reb. Circulating current flows.

Ea IV Zea Ia Load Eb Zeb Ib Ea = Ia Zea + V

Eb =Ib Zeb + VEa Ia + Ib =0 => Ia = - Ic Ia Xea Ea - EbIa Rea

aIb = IcIa =IcEb VIb Xeb Ib Reb

77POWER TRANSFORMER Transformer Connections and Operation:Conditions for Parallel Operation:Voltage ratio is equal. Ea = Eb, Zea = Zeb and Xea/ Rea < Xeb/Reb.Total out put is less than the sum of the individual outputs.

Ea = Eb I = Ia + IbIa XeaVIa Rea2Ia Zea = Ib Zeb22Ea IV Zea Ia Load Eb Zeb Ib Ea = Ia Zea + V

Eb = Ib Zeb + V

Ia = IbIbIaIb RebIabXeb88POWER TRANSFORMER Transformer Connections and Operation:Conditions for Parallel Operation:Voltage ratio is different, Ea > Eb, but (Xea/ Rea = Xeb/Reb) Circulating current flows and changes the power factors.

Ea I Ia XeaVIa Rea2Ea IV Zea Ia Load Eb Zeb Ib Ea = Ia Zea + V

Eb = Ib Zeb + V

Ia = I/2 + Ic

Ib = I/2 - IcIaIbIb RebIabXebIc

IcIcEb 99POWER TRANSFORMER Transformer Connections and Operation:Conditions for Parallel Operation:Voltage ratio is equal. Ea = Eb, Zea > Zeb and Xea/ Rea = Xeb/Reb.Load sharing is different.

Ea = Eb I = Ia + IbIa Xea = Ib XebVIa Rea = Ib Reb2Ia Zea = Ib Zeb2Ea IV Zea Ia Load Eb Zeb Ib Ea = Ia Zea + V

Eb = Ib Zeb + V

Zea > Zeb

Ia < Ib

IbIa21010POWER TRANSFORMER B. Transformer Connections and Operation:Vector group and clock hour numberGroup no.Phase displacement Clock hour no.10002180063-30014+300111111TransformerNormal conditionsV1Resultant Voltage in Delta Connected Ter Winding =zero I1/1 1 E2 I2/2 I2 2 IL + I1 I3/3 I3 3 E1E312POWER SYSTEM Power Transformer 3 Ph SupplyApplied VectorInduced FluxER1EY1EB1Induced VoltageVY1VB1NVR1R1Y1B1R1Y1B1RBYER1EY1EB1R2Y2B2ER2EY2EB2R3Y3B3ER3EY3EB31313POWER SYSTEM Power Transformer YNyn0d11 Induced VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y3ER1EY1EB1NER2EY2EB2NER3EB3EY3NInduced Vector1414POWER SYSTEM Power Transformer YNyn0d11 R1Y1R2Y2B1B2R3B3Y3NNApplied VectorInduced VectorConnected VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y3N1515POWER SYSTEM R1Y1R2Y2B1B2R3Y3B3NNApplied VectorInduced VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Power Transformer Induced Voltages: 1616POWER SYSTEM Power Transformer Induced Voltages: R1B1R2B2Y1Y2R3B3Y3NNApplied VectorInduced VectorInduced VectorR1Y1B1R2Y2B2R3Y3B31717POWER SYSTEM Power Transformer YNyn0d11 R1Y1R2Y2B1B2Y3R3NNApplied VectorConnected VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3R3VL-LVL-L1818POWER SYSTEM Power Transformer YNyn0d11 R1Y1R2Y2B1B2R3B3Y3B3R3Y3NNApplied VectorConnected VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y31919POWER SYSTEM Power Transformer YNyn0d11 R1Y1R2Y2B1B2R3B3Y3B3R3Y3NNApplied VectorConnected VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y32020POWER SYSTEM Power Transformer YNyn0d11 R1Y1R2Y2B1B2R3B3Y3B3R3Y3NNApplied VectorConnected VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y32121POWER SYSTEM Power Transformer YNyn0d11 R1Y1R2Y2B1B2R3B3Y3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y3NConnected Vector2222POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3B3NNNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector2323POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3B3NNApplied VectorInduced VectorInduced VectorR1Y1B1R2Y2B2R3Y3B32424POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3NNApplied VectorInduced VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3VL-LVL-L2525POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3Connected Vector2626POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3Y3B3B3R3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector2727POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3Y3B3B3R3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector2828POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3Y3B3B3R3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector2929POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3B3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector3030POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3B3NNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector3131POWER SYSTEM Power Transformer YNyn0d1 R1Y1R2Y2B1B2R3Y3B3NNNApplied VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3Connected Vector3232POWER SYSTEM Power Transformer Dyn11 R1B1Y1NAvailable VectorApplied VectorInduced VectorB1Y1R1R2Y2B2R1Y1B1Y1B1R1R2B2Y2N3333POWER SYSTEM Power Transformer Dyn11 R1R2B1B2R1Y1Y1NNAvailable VectorApplied VectorInduced VectorR2Y2B2R1Y1B1Y1B1R1VL-L3434POWER SYSTEM Power Transformer Dyn11 R1R2B1B2R1Y1Y1NNAvailable VectorApplied VectorInduced VectorR2Y2B2R1Y1B1Y1B1R1VL-LB1Y13535POWER SYSTEM Power Transformer Dyn11 R1R2B1B2R1Y1Y1Y2NNAvailable VectorApplied VectorInduced VectorR2Y2B2R1Y1B1Y1B1R1VL-LB1Y13636POWER SYSTEM Power Transformer Dyn11 R1R2B1B2R1Y1Y1B1Y1Y2NNAvailable VectorApplied VectorInduced VectorR1B1R2Y2B2R1Y1B1Y1B1R1VL-L3737POWER SYSTEM Power Transformer Dyn11 R1R2B1B2Y1Y2NNAvailable VectorApplied VectorInduced VectorB1Y1R1R2Y2B2R1Y1B1Y1B1R1VL-L3838POWER SYSTEM Power Transformer YNyn0d11 Group Testing R2Y2B1B2R3B3Y3NApplied VectorInduced VectorConnected VectorInduced VectorR1Y1B1R2Y2B2R3Y3B3B3R3Y3R1Y1NN3939POWER SYSTEM Power Transformer YNyn0d11 B1R3B3Y3Vector Group Confirmation Measure the VoltagesR1Y1NR3B3Y3R1Y1NR1Y1B1R2Y2B2R3Y3B3B3R3Y34040POWER SYSTEM Power Transformer YNyn0d1 R2Y2B2R3Y3B3NInduced VectorR1Y1B1R2Y2B2R3Y3B3Y3B3R3R1Y1B1NVector Group Confirmation4141POWER SYSTEM Power Transformer YNyn0d1 R3Y3B3R1Y1B1NVector Group ConfirmationR1Y1B1R2Y2B2R3Y3B3Y3B3R34242POWER SYSTEM Power Transformer YNyn0d11 andYNyn0d1 R1Y1B1R2Y2B2R3Y3B3Y3B3R3R3Y3B3R1Y1B1NVector Group ConfirmationB1R3B3Y3R1Y1NR1Y1B1R2Y2B2R3Y3B3B3R3Y34343POWER SYSTEM Power Transformer YNyn0d11 B1R3B3Y3Vector Group ConfirmationR1Y1NR1Y1B1R2Y2B2R3Y3B3B3R3Y34444POWER SYSTEM Power Transformer YNyn0 R2Y2NB2RYNBR1----RY1----YNB1----BVector AvailableVector AppliedVector GeneratedVector AvailableR2Y2NB2R2Y2B2R1Y1B1RYBRYB4545POWER SYSTEM R2Y2B2R1Y1B1BRYBRYR2----BY2----RNB2----YVector AvailableVector AppliedVector GeneratedVector AvailableY2----RR2----BNB2----YR1----BY1----RNB1----YRYNBPower Transformer YNyn0: Phase sequence is not Changing with shifting of phases 4646POWER SYSTEM Power Transformer YNyn0: Phase sequence is not Changing with shifting of phases R2Y2NB2RYNBR1----RY1----YNB1----BVector AvailableVector AppliedVector GeneratedVector AvailableR2Y2NB2R2Y2B2R1Y1B1RYBRYBR2Y2B2R1Y1B1BRYBRYR2----BY2----RNB2----YVector AvailableVector AppliedVector GeneratedVector AvailableY2----RR2----BNB2----YR1----BY1----RNB1----YRYNB4747POWER SYSTEM Power Transformer YNyn0d11 B1----BApplication of Phase Sequence for Vector Group ConfirmationR3B3Y3R1Y1B1R3Y3B3B3R3Y3R1----RY1----YNB1----YR3B3Y3R1Y1B1R3Y3B3B3R3Y3R1----RY1----BN4848POWER SYSTEM Parallel OperationPossible Vector Groups for parallel Operation:

Trans. A:Star/Star Delta/DeltaDelta/Star Star/Delta

Trans. B:

Star/StarYesYesNoNoDelta/DeltaYesYesNoNo

Delta/StarNoNoYesYesStar/DeltaNoNoYesYes

4949POWER SYSTEM Parallel Operation: Star/StarR1Y1B1R2Y2B2ER1EY1EB1NER2EY2EB2NR1Y1B1R2Y2B2ER1EY1EB1NER2EY2EB2NTrans.-A YNyn0Trans.-B YNyn05050POWER SYSTEM Parallel Operation: Delta/DeltaTrans.-ATrans.-BR1Y1B1Y1B1R1R2Y2B2Available VectorApplied VectorR1R1B1Y1NB1Y1Available VectorB1Y1R1Y1B1Y1B1R1R2Y2B2Trans.-A Dd0Trans.-B Dd05151POWER SYSTEM Parallel Operation: Delta/StarR1Y1B1Y1B1R1Available VectorApplied VectorR1R1B1Y1NB1Y1Available VectorR2Y2B2R2B2Y2NR1Y1B1Y1B1R1R2Y2B2Trans.-A Dyn11Trans.-B Dyn115252POWER SYSTEM Parallel Operation: Delta/Star & Star DeltaTrans.-A Dyn11R1Y1B1Y1B1R1Available VectorApplied VectorR1R1B1Y1NB1Y1Available VectorR2Y2B2R2B2Y2NR2B2Y2R1Y1B1R2Y2B2B2R2Y2NTrans.-B YNd11 5353POWER SYSTEM Parallel Operation: Delta/Star & Star DeltaTrans.-A Dyn1Available VectorApplied VectorR1B1Y1NAvailable VectorR2Y2B2R1Y1B1NR1B1Y1NAvailable VectorApplied VectorR1B1Y1NAvailable VectorR2B2Y2R1Y1B1R2Y2B2B2R2Y2NTrans.-B YNd11R1B1Y1N5454TRANSFORMER 100 MVA 220/66-33/11kV Power Transformer (CGL)Rating:50/70/100 MVAVoltage:220/66-33/11 kVCooling:ONAN/ ONAF/ OFAFCapacity: HV 105.41 MVALV 100.00 MVATV 33.33 MVAVector:YNyn0d11Type of Bushing:HV 245 kV, 800 AmpLV 72.5 kV 3150 AmpTV 36 kV 3150 AmpHVN 36 kV 630 AmpLVN .Location of WTI CT:1V, 2U & 3WLDC CT:1VPI:> 1.5Tan delta (30V):< 0.5 at 20 deg CBDV:>60 kVWater Content: 5000 M Ohms55TRANSFORMER 100 MVA 220/66-33/11kV Power Transformer (CGL)Recommended Settings:

Over Current:120 % IbDifferential Relay:1 %Over Flux:10 %Neutral Grounding Resistance:< 0.1 Ohms

Fan ON:60 deg CFan OFF:50 deg C

Pump ON:80 deg CPump OFF:60 deg C

OT Alarm:85 deg COT Trip:95 deg C

WT Alarm:100 deg CWT Trip:110 deg C

56LINE PROTECTION

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