Rocky58
Member
- Location
- Lexington, KY
We have a total of 9 ATS48C66Y Soft Starts that are operating 500HP Hammer Mill Motors (WEG) for wood chip processing. On 8/3/2015 the drives were locked out for servicing other areas of the plant. When we went to restart later on in the afternoon the drives would not start the motors. We have experienced either overcurrent fault on the soft start or it has tripped the circuit breaker (1000 A - set at 5x Is). 5 days before this occurred the hammers were replaced in the mill portion and the motors all ran since then. Our incoming voltage (unloaded) is in the 492 range and we have seen dips in the 450 range but only during initial startup. With all motors on line, along with associated motors we average in the 478 to 485 range. We have uncoupled the motors from the load and the soft starts will start and run the motors. When we recouple and attempt to start again, we see motor rotation and hear a very loud rumbling noise (hard to describe). It's not like a single phasing hum that we've all heard in the past. We do have Schneider involved but I'm trying to reach outside the box for some assistance. This all occurred at the same time. Two months earlier we experienced shorting of the SCR's on five units and we replaced the starters and everything has run fine for two months. We've meggered the motors and the feeder cables and we have over 100 megohms to ground at 1000V. Any suggestions would be greatly appreciated.