On Mon, 10 Dec 2007 00:40:48 +0000, Harold and Susan Vordos wrote:

"RainLover" wrote in message
...
Hey guys,

I was looking at getting a KILN that requires 220 3-phase (31amps) to
run. Does anyone know what HP rotary phase converter I'd need to run
it?

Thanks!

James (seattle)

www.jameskelseystudios.com



I'm of the opinion that you should look for a different kiln. There
are no shortcuts to providing the needed wattage---be it with three
phase or single phase. The demand on amperage for the phase converter
will be just as great as if you went single phase directly to the kiln,
so I see nothing gained with the three phase unit aside from lower
amperage per leg. Overall, you'll still consume the same amount of
power, and you'll be paying for the phase converter and its losses in
the bargain. You'd be better served to buy a kiln that is single
phase, with a higher current demand (because it's only single
phase)-----and avoid the phase converter. I'd have a totally different
attitude were you powering a machine tool. I wonder if Bruce would
agree?

Harold

Unless you got a real steal on the kiln, _and_ it can be easily rewired
for 220 single-phase, I agree with Harold.

Three phase power is great for rotating machinery, because you get better
starting torque and smoother running.

Three phase power is nice for he-man power electronics because you need
less (or no) smoothing capacitors after rectification.

Three phase power has little advantage other than smaller wires for
heating, because a heater doesn't care if the power is perfectly constant
or if it pulses at 120Hz -- it gets just as hot either way.

Were it mine, I'd look to see if the heaters are connected in a delta,
and if so I'd say "yipee!" and reconnect them in parallel for single-
phase operation -- unless I had to buy enough parts that I could just get
a new kiln.

If you have to ask, I'm not going to recommend that you do the above --
just check to see if it gives directions for wiring it as single-phase,
and if it doesn't start shopping around for a unit to replace it with.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html