Re: Converting to "Pig Power"

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

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 11:22 AM 3/11/2004 -0700, you wrote:
>Original poster: Yurtle Turtle <yurtle_t-at-yahoo-dot-com>
>I have a number of high amperage variacs, including
>two at 120 volt 45 amps, three at 540 volt 33 amps,
>two at 240/280 volt 28 amps, and a pair of ganged
>120/140 volt 20 amp ones, so they can easily be found.
>Check for HamFest's in your area, look for scrap yards
>and don't forget garage/estate sales, and eBay.
>
>Actually, a pair of ganged 120/140 volt variacs is the
>best. When using 240/280 variacs on residential
>120/240, one leg is always hot, so you have to be
>careful.
>
>Variacs can be driven to twice their current ratings
>for short runs if you allow them to stay cool.
>
>You mentioned that you are using a relay. I'd be on
>the lookout for a real motor starter, sometimes
>referred to as a contactor. You need big contacts to
>handle big amps, especially if you want to make or
>break during high power.
>
>And finally, if you are limited to a single 120 volt
>variac, you can always wire it up vary from 120 volts
>to 240 volts, giving you some control.
>
>Adam


And real motor starters often have something else very, very useful, a 
thermally actuated circuit breaker. Handles high peak currents without 
tripping, but keeps your stuff from melting (just like in the motor 
application).

Real motor starters also usually have auxiliary contacts (or they can be 
added easily) to give status.