Wire Insulation Thickness

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Wire Insulation Thickness
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 26 May 1998 23:22:55 -0500
Approved: tesla-at-stic-dot-net

----------
From:  Bert Pool [SMTP:bertpool-at-ticnet-dot-com]
Sent:  Tuesday, May 26, 1998 5:36 AM
To:  Tesla List
Subject:  Re: Wire Insulation Thickness

 
> ----------
> 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.

Gary, 
Bill and I are using crappy *thin* enamel (not even formvar) wire on our Wart 
Hog coil - 13 kilowatts and 12+ foot sparks with no failures on the coil (this 
time around).  Enamel wire works for very high power coils; I consider anything 
over 10 kw very high power.  Having proudly said that, our last run one year ago 
resulted in the damaging of our secondary - tuning, tuning, tuning!  You have to 
use a large enough top for field shaping and shading and use a breakout bar on 
the toroid and tune at ruduced power level before running the coil's power up.  
Do *not* over-couple a really big coil or you will have racing sparks - and at 13 
kw that means instant death for your windings.  These are my tips for setting 
up a big coil.  

Good luck.
Bert


> 
> 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
> 
> 


Bert Pool
TCBFW
bertpool-at-ticnet-dot-com