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Transformer

 * Original msg to: Nussbaum-at-silly-dot-com
 * Carbons sent to: usa-tesla-at-usa-dot-net

Quoting Ephraim Nussbaum <nussbaum-at-silly-dot-com>;

> Well I just unpotted another transformer this one 15kv and it 
> seems to have the coils the way you drew, but I have another 
> problem.

> When I first picked it up, I tested it and I got nice sparks 
> from one lead. When I tried the other lead I got nothing, so I
> removed the cover, removed the tar on the side of that lead 
> until I got down to the wire that comes out of the ceramic 
> spacer. Where the wire is attached to the windings there was a
> small copper plate with a niche in it and tar had gotten 
> between the plate and windings. Can I just reattach flat 
> against the windings (I don'tknow where it was attached).
> Also there was a small wire coming out of the plate, maybe this
> is what was attached to the windings.

This model of transformer uses a small metal plate as a connector
between the winding and the lead wires. I have also seen HV
windings on neons that used the same connector system to the core
at the other end.

> I, through cleaning, tore a few of the windings (5 or 6) does 
> it matter? I held the plate against the windings with an  
> insulated screwdriver and then tested to see if I would sparks
> off the lead and I still didn't get anything. Any help would be
> appreciated. 

It sounds as if the winding is broken down. You are obviously
experienced enough to know that the HV windings are very
delicate. The wire is not much thicker than a coarse hair. In
order to salvage the winding (if it indeed can be salvaged) you
need to isolate the end of the winding, clean the wire very
carefully, and imbed the last 1/4 inch or so in a nice solder
connection to a new lead wire. If the connection is electrically
poor or intermittant the resistance will cause the end of the
winding to heat up and melt, opening the circuit again. 

Losing a few turns at the end of the winding will not really
affect things, as long as the end of the winding can be located
and a decent connection to it can be made.

The real problem occurs when a winding has failed internally. The
wire, being so delicate, can easily short or burn due to a defect
in the materials or the construction. If you are not able to coax
any output from a winding after ensuring a decent electrical
connection at both ends, pitch it without a second thought. I
hang onto the cores and all good windings until I can swap in a
winding from another transformer with the same type failure.

Richard Quick


... If all else fails... Throw another megavolt across it!
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