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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