Re: strange variac problem

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

Original poster: "David Sharpe by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

Greg

Are you sure that it is a 240V Variac?  I have run a 140V Variac on
240V with a resistive ballast.  With about 7.2kVA+ being drawn from
line, I was probably very lucky to see about 3kVA making it to the HV.

If the Variac is saturating, you will know it.  It will be humming loudly,
and line currents will start rapidly increasing toward the moon...

Check your line voltage with a o'scope.  If you are saturating, wave
distortion will hose up your analog meter readings... (that is you need true
RMS voltage and current meters).   FWIW.

Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA


Tesla list wrote:

> Original poster: "Mr Gregory Peters by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>
>
> I was running my small (15kV/90mA) coil yesterday. I hooked up my 10amp
> variac, which I have tested with my multimeter and shown that it
> smoothly varies the voltage from 1- 270v. However, even with the full
> 270v, I needed a very small gap to get reliable firing. I plugged the
> coil straight into the 240v socket and was able to get reliable firing
> with very wide gaps. What's going on? It's almost as if the variac is
> sucking all the power. I could only get 1 foot sparks with the variac
> hooked up but 4 foot sparks without.
>
> Cheers,
>
> Greg Peters
> Department of Earth Sciences,
> University of Queensland, Australia
> Phone: 0402 841 677
> http://www.geocities-dot-com/gregjpeters