Re: Problems with current limiting system


 Just my ten cents worth,

 Have just completed testing current control on my pig with two variacs, one of
28 amp 240 volt for voltage control and the other 40 amp 240 volt oil cooled
which does the current control. I shorted out the horns on the pig, the large
variac will control the current from almost nil to over 65 amp for as long as
the circuit breakers would hold which was for as long as I like. One thing
though, I run the voltage control variac using the tap to give me 270 volts on
the output, I am uncertain as to how much of the variac winding is actually
'seeing' the full current of the pig under load - perhaps someone could let me
know?, but I can vouch for using a large variac to continuously vary and
control a pig under load.

kind regards

 Robin Copini in OZ.

Tesla List wrote:

> Original Poster: "Dr. Resonance" <Dr.Resonance-at-next-wave-dot-net>
> to: Mike
> There was not enough iron for effective control.   For effective current
> limiting with a pole pig you really need a C-core or E-I core configuration
> with a small gap --- approx 120 mils per side.
> Regards,
> Dr.Resonance
> -----Original Message-----
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
> Date: Saturday, July 24, 1999 7:19 PM
> Subject: Problems with current limiting system
> >Original Poster: "Coiler" <mycroft-at-access1-dot-net>
> >
> >Well, I just got a nasty surprise, and am looking for input from
> >someone that is more familiar with this than I.
> >I wound an iron core coil, hoping to use it as a limiter for my pig.
> >about 10lbs of iron wire form a straight core. I wound about 400 turns
> >of 10AWG wire on this. Measuring current with my 110V variac
> >I found that I got 10A at 130V. So I figured I would get around 25A
> >at 240. Boy was I wrong.
> >Wired in series with my pig, shorted pig output. Meter shows 83A being
> drawn
> >and considering how the wires were jumping, I'd belive it.
> >
> >Is it possible I saturated the iron, even though it is a straight rod?
> >
> >*HELP*
> >Thanks!
> >Michael Baumann
> >Coiler, Homebrewer, Nerd. mycroft-at-access1-dot-net
> >
> >
> >