Transformer Construction

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    31-Dec-2015
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Transformer Construction. Three-Phase Transformer. Transformer Action -- DC. Opposes battery voltage. Opposes flux buildup. Transformer Action -- AC. Opposes V T Opposes Φ M. “No-Load” Condition. “No load” condition continued. I o = I fe + I M - PowerPoint PPT Presentation

Transcript of Transformer Construction

  • ECE 441*Transformer Construction

    ECE 441

  • ECE 441*Three-Phase Transformer

    ECE 441

  • ECE 441*Transformer Action -- DC

    ECE 441

  • ECE 441*Opposes battery voltageOpposes flux buildup

    ECE 441

  • ECE 441*Transformer Action -- AC

    ECE 441

  • ECE 441*Opposes VT Opposes M

    ECE 441

  • ECE 441*No-Load Condition

    ECE 441

  • ECE 441*No load condition continuedIo = Ife + IMIo = exciting currentIo provides the magnetizing flux and the core lossIfe = core-loss currentIfe = VT / RfeIM = magnetizing currentIM = VT / jXM

    ECE 441

  • ECE 441*No-Load Excitation mmfNo-Load Core Loss mmfMagnetizing mmf

    ECE 441

  • ECE 441*

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  • ECE 441*Close the load switchSecondary current will set up an mmf in OPPOSITION to the primary mmf. The core flux will DECREASE to

    ECE 441

  • ECE 441*The decrease in flux causes a decrease in the counter-emf EP, and the primary current will increase by an amount known as IP,load, the load component of the primary current. Additional mmf due to this current adds to the magnetizing flux.

    ECE 441

  • ECE 441*Primary current increases until NPIP,load = NSIS. The flux M and primary emf EP return to the same values as before the switch was closed.

    ECE 441

  • ECE 441*Final steady state primary current under loaded conditions is

    ECE 441

  • ECE 441*Component Fluxes Loaded Transformer

    ECE 441

  • ECE 441*P = net flux in window of primary S = net flux in window of secondarylp = leakage flux of primary ls = leakage flux of secondaryM = mutual fluxP = M + lpS = M ls

    ECE 441

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