[AMPS] 100KW induction furnace

[Roy Koeppe]

I once built a crystal set....

K6XK
-----Original Message-----
From: Kf8od@aol.com <Kf8od@aol.com>
To: amps@contesting.com <amps@contesting.com>
Date: Wednesday, January 20, 1999 2:42 PM
Subject: [AMPS] 100KW induction furnace


>
>Hi All,
>
>Having a problem at my shop with a 100kw induction furnace. The furnace
heats
>a billet for drop forging. The problem is when you start the funace at
about
>50% the GFI in the switch gear trips. If started at a lower percent it's
fine.
>But that is not good enough. The unit operates at 480v 3phase 2000 amps
input
>to the power supply. The output is 1200 vdc 1980 amps at 1000hz. The input
is
>fed to the rectifier board which are SCR's. Then to a reactor on both
positive
>and negative. then to a inverter. The GFI tripping is a inducation of a
>unbalanced load, according to one individual. My thought was a step start
on
>primary of the power supply. The capacitors that shunt the SCR's and the
SCR's
>themselves look like a short for a instant. There is one thing I noticed on
>the schematic that I thought was not rite, they have the SCR's shunted with
a
>resistor and capacitor in series. Shouldn't they be in parallel. The reason
>for my asking for help is that everything you think you would like to try
cost
>50k. Everything is water cooled, resistors, capacitors even the conductors
in
>the unit.  So, anybody out there with any experience in this area out
there?
>
>Thanks for the help!
>
>73, Mike
>KF8OD
>
>Long live QRO!
>
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