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Transformer with bifilar wound primary (bifilar has higher voltage between turns)?

  1. Aug 15, 2011 #1
    If a transformer has a bifilar wound primary coil will the secondary voltage still be equal to the transformer's turns ratio?

    Bifilar coils when connected together in the proper way have a much higher voltage between turns. Instead of the voltage across each turn being equal to the total voltage divided by the number of turns the voltage between each turn is 1/2 the applied voltage.

    Seems to me that the secondary voltage would be equal to the turns ratio, and the only difference is that the primary winding would have a high capacitance....Don't see what purpose that would serve....
  2. jcsd
  3. Aug 15, 2011 #2


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    Re: Transformer with bifilar wound primary (bifilar has higher voltage between turns)

    It depends what you mean by "connected together in the proper way"

    Bifilar windings can be used for (at least) two different purposes.

    1. Parallel connected Bifilar windings (or multifilar windings) can be used to reduce skin effect by increasing the relative amount of surface area compared with using one larger wire. This usage of bifilar has no effect on the volts per turn or the required insulation strength.

    2. Primary / secondary combined together in a mutli-filar winding is sometimes used to get the tightest possible magnetic coupling (minimum leakage inductance). This comes at the expense of increased capacitive coupling (poor HF isolation) and reduced dielectric isolation between primary and secondary (compared with having more physically separated winding layers)
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