Re: 10KV RMS -at- 300MA (in oil!)
Subject: Re: 10KV RMS -at- 300MA (in oil!)
Date: Mon, 16 Jun 1997 07:42:40 -0400
From: Steve Falco <sfalco-at-worldnet.att-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Following the death of my neon, I decided to switch to the H&R copier
transformers I bought a few months back. Having already toasted one, I
wanted to see the new ones survive. Following Skip's advice, I removed
some of the high voltage insulation - I actually got down to the outer
layer of the windings on the side where the HV leads were.
I found that there are at least 3 varients of this transformer:
1) Quick connect wires - this is the one I burnt up, and probably the
most likely varient to do so.
2) Directly connected wires, with just a thin plastic sleeve over the
inner lead wire. Better, but...
3) Directly connected wires with an extra fiberglas/silicone rubber
boot. In addition to the thin plastic sleeve, this varient has a fairly
thick mica plate between the secondary and the inner lead wire. Pretty
I decided to try submerging the transformers in oil, for extra
protection. I bought two Coleman "8 quart personal coolers". These are
insulated, well reinforced plastic tubs with fairly tight fitting lids
and a sturdy carrying handle. They are a fairly tight fit to the
transformers - perhaps a half inch of clearance, so not too much oil is
wasted. I also cut pieces of .093 LDPE, and wedged them here and there
to keep all the wires away from the transformer coils, to guarantee a
Since the cover fits fairly tightly, I replaced the thick HV secondary
leads with thinner PVC wire. All wires were draped over the sides of
the cooler, then the lid was locked in place. I may eventually use some
silicone caulk to seal up the coolers, but for now it is nice to be able
to open them for inspection.
I am not using the resonating capacitors that came with the
transformers. I need to rig up an HV probe to see what I am really
getting out of them. There have been no problems of any kind on the
short test runs I have done. I don't have a variac so I have just been
plugging into full line voltage. (YeeeHaaa).
Spark length is just a few inches now, because I only have a .005 uF
cap. Building something in the .05 - .10 range will be my next