toroidial transformer winding question
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Posted by on May 24, 2006, 3:18 pm
Please log in for more thread options I have several toroidial transformers that have two 115v windings and two 25v windings on each. The way I understand electricity each 115v winding would only go 1/2 way around the toroid then the 25v winding is on top of that winding is this correct? or do both windings go all the way around? that would be more of a 1:1 isolation transformer (if the 25v windings were gone) Am I thinking correctly? Thanks Res. | |||||||||||||||||||||||||||||||||||||
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Posted by Rich Grise on May 24, 2006, 3:56 pm
Please log in for more thread options On Wed, 24 May 2006 12:18:31 -0700, cwaugs wrote: They're isolated electrically, just because the wires are insulated. The thing that would change with the different winding patterns would be interwinding capacitance and possibly the mutual inductance, or the magnetic coupling between the windings, which would only affect effeciency. Hope This Helps! Rich | |||||||||||||||||||||||||||||||||||||
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Posted by Bob Eld on May 24, 2006, 7:11 pm
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> I have several toroidial transformers that have two 115v windings and
> two 25v windings on each. The way I understand electricity each 115v > winding would only go 1/2 way around the toroid then the 25v winding is > on top of that winding is this correct? or do both windings go all the > way around? that would be more of a 1:1 isolation transformer (if the > 25v windings were gone) Am I thinking correctly? Thanks Res. You are not thinking correctly. Any winding or windings can be primary(s) or secondary(s). It does not matter where on the core they are wound except for issues like capacitace and leakage inductance. All windings should cover as much of the core as possible depending on the number of turns and the wire thickness. Each 115 winding may go more or less than half way or they may go more than one complete layer, again depending on the turns required. It is possible that the two 115 windings are in three or four layers. It is not knowable with the information provided. If you provide the physical size of the transformer(s) the power level and frequency, typical windings can be estimated, both number of turns and wire size. Of course there are other factors complicating the issue such as allowable temp rise, maximum flux density, allowable leakage flux, maximum inrush current, necessary magnetizing current, efficiency, acoustic noise, allowable waveform distortion, creepage distance and other factors that can complicate a real design. Bob | |||||||||||||||||||||||||||||||||||||
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Posted by John Larkin on May 24, 2006, 10:45 pm
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On 24 May 2006 12:18:31 -0700, cwaugs@cs.com wrote: >I have several toroidial transformers that have two 115v windings and
>two 25v windings on each. The way I understand electricity each 115v >winding would only go 1/2 way around the toroid then the 25v winding is >on top of that winding is this correct? or do both windings go all the >way around? that would be more of a 1:1 isolation transformer (if the >25v windings were gone) Am I thinking correctly? Thanks Res. Usually one winding is wound, pretty much evenly all around the core, making the donut fatter. A layer of insulating tape goes next, then the next winding, also more-or-less evenly distributed around the core. And so on. Yes, the two 115v windings can be used to make an isolation transformer. John | |||||||||||||||||||||||||||||||||||||
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Posted by Pooh Bear on May 25, 2006, 10:24 am
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John Larkin wrote: > On 24 May 2006 12:18:31 -0700, cwaugs@cs.com wrote:
> > >I have several toroidial transformers that have two 115v windings and
> >two 25v windings on each. The way I understand electricity each 115v > >winding would only go 1/2 way around the toroid then the 25v winding is > >on top of that winding is this correct? or do both windings go all the > >way around? that would be more of a 1:1 isolation transformer (if the > >25v windings were gone) Am I thinking correctly? Thanks Res. >
> Usually one winding is wound, pretty much evenly all around the core, > making the donut fatter. A layer of insulating tape goes next, then > the next winding, also more-or-less evenly distributed around the > core. And so on. > > Yes, the two 115v windings can be used to make an isolation > transformer. You can't legally use it that way for isolation since the insulation doesn't meet safety regs. Graham | |||||||||||||||||||||||||||||||||||||
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> two 25v windings on each. The way I understand electricity each 115v
> winding would only go 1/2 way around the toroid then the 25v winding is
> on top of that winding is this correct? or do both windings go all the
> way around? that would be more of a 1:1 isolation transformer (if the
> 25v windings were gone) Am I thinking correctly? Thanks Res.