[the spyder]

Im just the computer geek, so bare with me...
We had a horrible powersurge at work the other day. The machine is a matsura h plus 630. Now do not ask me WHY I did this, but we like to fix what ever we can around here. Our local service techs like to screw us in the 4 figure range every time.

The whole building lost power, but when it came back on, the machine loaded then POP. The main 100amp breaker in the wall panel tripped. With some close inspection I found codes were being thrown on the Fanuc controller power supplies. There are 2. The first one was giving 7, a over voltage alarm, the second was giving 0, a over voltage alarm detected in the system alarm. Anyways. Some how I decided to tear apart the first unit, finding scorched components. The units are a three phase 230v to DC 325V converter. After removing the power supply, I found arcing carbon marks on the rear of the circuit board, between the massive transistor modules. These are directly tied into the 3 phase. The only damage on the circuit boards is around the smaller control interface for the transistors. Example, around the first transistor, the small control circuit has 3 resisters, 2 caps, and 1 diode blown.

What I really do not understand is there are 4 of these modules in a row. The 3phase inputs at the bottom of the unit. The first transistor is blown. The second is untouched. The third is again fried. The fourth is good. They are all chained together, one after the other on a buss bar. The controllers again are the same as above, 1st fried, 2nd fine, third fried. How is this possible? Now the machine was sitting idle when this happened. No load. Is it possible for a surge to "jump" between the legs of the 3 phase? There are inline power filters, rectifiers, but no real surge suppressor.

Has anyone else had this happen? I tested the transistors today and one is completly fried, the other 3 look good. I get to put this whole thing back together tomorrow morning. YAY.