Re: New tranny arrived today, need ballast advice
In a message dated 00-02-22 11:23:04 EST, you write:
<< Original Poster: "Adam" <adamsmith-at-mediaone-dot-net>
> My new GE transformer arrived today, and I'd like to get some suggestions on
> how to current-limit it for 120V/20A service, and how many VA I can expect
> to use this at. The transformer is the following type:
> General Electric
> JVW-5 "Hi-Bute 60"
> 1500 V.A. (30 deg rise)
> 120:1 (14,400-to-120)
> Anybody use this same model? I know i've seen similar on some of the webring
> sites. If that's your site, what are you ballasting it with? :-)
I use the hi-Butes, same specs. Richard Hull used to run them
up to triple their ratings. Nice xfrmers, but as dangerous as a pole pig.
> Up to this point, I have only run my coils with banks of NSTs, so I really
> don't know the first thing about practical pig/pot ballasting solutions.
> I've read everything I can find in the pupman archives relating to
> ballasting and potential transformers, but I still have no concrete examples
> to go by. What I have to work with are some NSTs, a pair of MOTs, and some
> old hotplates I've gotten from peoples' trash (the kind with a flat spiral
> heating coil--good power resistors?).
You can use a welder, a variac, or a homemade ballast. I'm using the
homemade ballast now. It's about 300 turns of #12 wire on a 3" by
19" pvc form, with straight transformer iron laminations tossed into
the center. I once tried the variac method but it drew double the
power. I think that was because I'm using reso-charging which
caused saturation of the core. If you use a higher break-rate, this
probably wouldn't be such a problem because the primary voltage
will never go that high. You could try using MOT's as ballast, but I've
never tried it.
> My last question is: how many V.A. can I really use this thing at, for short
> (under 30 second) runs. In other words, ignoring the heat factor associated
> with continuous operation, how much current can I really safely extract from
> this tranny?
> Thanks a bunch,
> Adam >>