Electrical Machines LSEGG216A 9080V. Transformer Operation Week 4

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Transcript of Electrical Machines LSEGG216A 9080V. Transformer Operation Week 4

  • Electrical MachinesLSEGG216A9080V

  • Transformer OperationWeek 4

  • Transformer OperationV+CIVILVoltageCurrentMagnetic Flux

  • Transformer OperationApplied VoltageInduced VoltageInduced Voltage in SecondaryResultant CurrentV1V1V2IM

  • Induced Voltagemax =Maximum instantaneous fluxF = FrequencyN = Number of turnsBmax = Maximum permissible flux density in WbA = CSA of core in m2

  • Transformer OperationV1IMIeIoIe= Iron loss currentIo = No load current

  • Transformer OperationV1V1V2IoI2I1I1

  • Transformer OperationV1V1V2IoI2I1I1

  • Transformation RatioMagnetic flux is common coilsTherefore the voltage can be varied by changing the number of turns

  • Transformation RatioV1=N1N2V2== k= Transformation Ratio

  • Transformation RatioV1x I1N1N2=V2 x I2=I1I2

  • Transformation RatioV1x I1VAV2 x I2kVAPower InPower Out

  • Transformation RatioV1x I1V2 x I2200200V100V400K = 2

  • Voltage RegulationEIVoltage Drop Due to RVoltage Drop Due to XLVResistanceInductanceCoils have both

  • Voltage RegulationEIVLagging PF of 45V less than E

  • Voltage RegulationEIVLeading PF of 45V More than than E

  • Voltage Regulation100 x VNo Load V Full LoadVFull LoadR% =If PF = Unity100 x I x (R x cos + XL x sin)VFull LoadR% =

  • Transformer Basic TestsOpen Circuit TestShort Circuit TestOil TestsElectrical InsulationPolarityContinuity

  • Open Circuit TestUsed to determine Iron LossesSupply = Rated Voltage

  • Open Circuit TestWattmeter reading V1IMIoIeSupply Voltage Ammeter reading

  • Short Circuit TestUsed to determine Copper LossesSupply Adjusted = Rated Secondary Current