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Wire Insulation Thickness


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From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent:  Tuesday, May 26, 1998 9:27 PM
To:  Tesla List
Subject:  Re: Wire Insulation Thickness

to: Gary

The output spark does depend a lot on current in the spark channel and
available power.  With a real coil a 100 inch spark does not represent 1.8
MV.  A coil with a 9 ft long spark represents 1,000 kV and a coil with a 5
ft spark represents 500 kV.  This data was taken with measurements on an
operating system (9ft spark at 7 kva input and 5 ft at 4 kva input power
level).  Hope this helps clarify the potential vs spark length.

DR.RESONANCE-at-next-wave-dot-net


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> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Wire Insulation Thickness
> Date: Monday, May 25, 1998 9:05 PM
> 
> 
> ----------
> From:  gweaver [SMTP:gweaver-at-earthlink-dot-net]
> Sent:  Monday, May 25, 1998 4:37 AM
> To:  Tesla-at-pupman-dot-com
> Subject:  Wire Insulation Thickness
> 
> I don't think the insulation on enamel coated copper wire is good enough
for
> very high powered Tesla Coils.
> 
> I used a micrometer to check 2 lengths of enamel coated copper wire every
> 1".  Then I removed the insulation and checked the diameter again.  I was
> surprised that acetone would not remove the enamel coating.  I heated the
> wire over a candle to burn off the insulation then cleaned off the carbon
> with 0000 steel wool.
> 
>
----------------------------------------------------------------------------

> 
> Here are the results for #20 enamel coated copper wire.
> 
> A = Wire diameter with enamel coating on the wire.
> B = Wire diameter with enamel coating removed.
> C = Insulation thickness including both sides.
> D = Minimum insulation thickness of one side only.
> 
>    A            B             C              D
> 
> .0350         .0301         .0047
> .0348         .0301         .0047
> .0347         .0301         .0046
> .0348         .0301         .0047
> .0350         .0300         .0050
> .0345         .0301         .0044          .0022
> .0345         .0300         .0045
> .0345         .0301         .0044
> .0345         .0300         .0045
> .0345         .0300         .0045
> 
>
----------------------------------------------------------------------------

> 
> Here are the results for #24 enamel coated copper wire.
> 
> A = Wire diameter with enamel coating on the wire.
> B = Wire diameter with enamel coating removed.
> C = Insulation thickness including both sides.
> D = Minimum insulation thickness of one side only.
> 
>    A             B            C             D
> 
> .0238          .0202        .0036
> .0240          .0202        .0038
> .0238          .0202        .0036
> .0235          .0202        .0033
> .0235          .0201        .0034
> .0235          .0201        .0034
> .0235          .0201        .0034
> .0235          .0201        .0034
> .0235          .0201        .0034
> .0232          .0201        .0031        .00155
> 
>
----------------------------------------------------------------------------

> 
> I measured the arc length on a 15K neon and it measures .812 maximum.
> 
> That equals 18,460. volts per inch.
> 
> 1" = 18.46 KV
> 
> 10" = 184.6 KV
> 
> 100" = 1.846 MV
> 
>
----------------------------------------------------------------------------

> 
> The rule of thumb is about 1000 turns of wire on a secondary coil.
> 
> A coil with 1000 turns of enamel coated copper wire will have the follow
> volts per turn based on the different length discharge sparks.
> 
> 10" discharge spark = 184.6 KV =184.6 volts per turn.
> 
> 50" discharge spark = 923 KV = 923 volts per turn.
> 
> 100" discharge spark = 1.846 MV = 1846 volts per turn.
> 
> 150" discharge spark = 2.769 MV = 2769 volts per turn.
> 
>
----------------------------------------------------------------------------
-
> 
> Minimum insulation thickness for #20 wire is .0022
> 
> Minumum insulation thickness for #24 wire is .00155
> 
> 2 wires wound on a coil side by side will have a insulation thickness
double
> this figure.
> 
> I don't know the exact voltage rating for enamel insulation but I bet its
> not high enough to hold up to 2769 volts or 1846 volts or even 923 volts.
> 
>
----------------------------------------------------------------------------

> 
> This probably explaines why my 6" coil that produces 54" discharge sparks
on
> 1350 watts has 11 burn spots on it between the turns.  Thats 996 volts
per
> turn on the secondary coil.
> 
> My 10" coil that produced 126" discharge sparks shorted out and caught on
> fire. That was 2325.9 volts per turn on that coil.
> 
> None of my 4" coils have burn spots on them.  The largest one produces 
24"
> discharge sparks from 750 watts.  Thats 443 volts per turn on the
secondary
> coil.
> 
>
----------------------------------------------------------------------------

> 
> I was thinking it might be a good idea to wind a plastic fishing line
> between the wires on a large coil to increase the insulation rating.  The
> extra spacing should help arcing between turns.
> 
>
----------------------------------------------------------------------------
-
> 
> What do you think?
> 
> Does this make sence?
> 
> 
> Gary Weaver
>