Stretch wrap happiness!! - 20 minute repair...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi All,

While running my CW coil at 900 watts full power, it burst into flames!!  I 
miss aligned the secondary coil right up against the primary and it arced 
over.  At first, I was sure I had destroyed the secondary:

http://hot-streamer-dot-com/temp/WrapBurn01.jpg

A 900 watt arc for about the 3 seconds it took me to hit the kill 
switch!!  Looks bad doesn't it!!

But this is the coil I never coated with polyurethane but rather just 
wrapped with commercial stretch wrap used for packing boxes:

http://hot-streamer-dot-com/temp/WrapBurn05.jpg

I was hoping the form would be OK and I would just need to rewind the 
wire.  Since it was uncoated under the wrap, it should come right off for 
re-wrapping.

I was stunned to see that the wrap had taken most of the heat and the 
damage to the coil was very small.  The wrap resisted damage to the coil 
except for the actual small arc area and protected everything else:

http://hot-streamer-dot-com/temp/WrapBurn02.jpg

The wrap self extinguished, burned fairly oderlessly,  but it also 
protected the coil very well!!  I just rubbed the small area with alcohol 
and kevlar cloth which removed the carbon.  and the damage was very slight now:

http://hot-streamer-dot-com/temp/WrapBurn04.jpg

I coated the area with two part epoxy and like 20 minutes later the coil is 
good to go again!!

http://hot-streamer-dot-com/temp/WrapBurn03.jpg

I had arced the OLTC a few times and the wrap did very well there too.  But 
this is the first time it had a real sustained CW high voltage arc fire to 
face.  The plastic wrap does not "stick" when melted and it can absorb a 
great deal of damage.  It protects the coil from physical damage very well 
and it can be removed and replaced in a few minutes!

I don't think I will ever coat a coil with anything else from now on!!

Cheers,

	Terry