What is the reason for spaces in secondary winding?

Discussion in 'General Electronics Chat' started by electronice123, Jan 7, 2010.

  1. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
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    I just stumbled across this picture a while back and wanted to ask: Why are there spaces in the secondary windings? What purpose does it serve?

    [​IMG]
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Must be separation for high voltage.

    Don't know offhand the insulation value of the coating on magnet wire, but it's not terribly high.

    By adding spacers between the windings, the effective insulation value is increased.
     
  3. rjenkins

    AAC Fanatic!

    Nov 6, 2005
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    They also improve the voltage rating by using a different winding technique - if you compare to a single spool of the same overall size, the windings typically run back and forth in layers. The start & finish of each pair of layers are a lot of turns apart but directly on top of each other so minimal insulation between them.

    The segmented former is wound one section at a time, then working from one end to another. The narrow segments mean only a few turns between any two wires in contact, so a vastly higher voltage rating is possible with the same wire insulation.
     
  4. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
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    Thanks for the answers. Just a few more things I would like to know?

    I was curious because I've never seen any HV transformers with secondary spacing like that....

    Is it just used when the transformer is not insulated with oil or when the wire coating is not strong enough?

    Is there a name for it? Is it very common?

    Do the spaces create capacitance within the transformer?
     
    Last edited: Jan 9, 2010
  5. SgtWookie

    Expert

    Jul 17, 2007
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    It's a coil bobbin.

    The flanges are there to effectively increase the voltage rating of the secondary.

    It would also help to delay the onset of core saturation.

    The extra spacing caused by the flanges would actually help to reduce the capacitance.
     
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I do believe many automotive and aeromotive high tension magnetos were bobbin wound.

    There are certainly some patents on such bobbins.
     
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