Re: [TCML] Turn-to-Turn short circuit

[BunnyKiller <bunnikillr@xxxxxxx>]

Hey  Matthew...

Looking at the picture and seeing the cross over at the end of your 
windings, take the time to re wrap those last couple of windings.  what 
concerns me is the mention of the usage of un-insulated wire....   ( you 
did ask about using insulated wire and I am going to asume that you used 
bare wire)...

What are you using this coil for?  Primary? Secondary?  Filter 
application?  it makes a difference in application.

Normal preferences apply as such

Primary: uninsulated but given enuf air gap to act as insulated
Secondary: definately insulated since turn to turn voltages can reach 
600+ V per turn
Filter Coils: still prefer insulation since turn to turn votlages can 
exceed 100V

If 50% of the wraps are in contact with each other you only have 50% 
uninsulated which increases the turn to turn voltage on the uninsulated 
wraps by an additional 50+ %....   thus needing more air gap between 
turns...

Scot D



Matthew Stevens wrote:

> This is a link to a picture of the coil in question
>
> http://drop.io/overlapped_coil_chokes/asset/100-1673-crop-jpg
>
> should I have used insulated wire?
> I am using an 8kv, 30mA NST for a power supply
> I think I understood what Stephen said, but I wanted to be certain before I
> powered up!
>
> On Sun, Mar 15, 2009 at 6:47 PM, Stephen Hiscock
> <stephenhiscock@xxxxxxxxx>wrote:
>
>  
>
> > I'm assuming you are talking about a single layer inductor? and the wires
> > are all touching each other? and they are all insulated?
> > (if not insulated then you will have to work out the insulation of air for
> > the gap between turns that you have)
> >
> > It depends on Voltage per turn (ie what is the final output voltage divided
> > by the total number of turns),
> > The insulation of the wire ie what voltage will produce a discharge through
> > the insulation of surrounding each individual wire,
> > and how far apart the overlapped the overlapped wire are from each other..
> > eg you could have 20 wires overlapped if the over lapped wires are only
> > overlapping one at a time and are all spaced far from each other.
> > but if all next to each other, then it may be problem
> >
> > But saying this simply, if the Voltage per turn exceeds the wire insulation
> > then you will have a problem ,but 99.99% of the time this won't apply.
> >
> >
> > regards
> > stephen
> >
> >
> > Matthew Stevens wrote:
> >
> >    
> >
> > > If two of turns on a coil overlap, will it cause a short? I am using two
> > > chokes I made from pens and wire as RF filters, and one (only one) of the
> > > turns overlaps another. Just wondering if this would cause a problem,
> > > before
> > > I put current to the coil!
> > >
> > > Thanks!
> > >
> > > Matthew
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