Servo drive issues

Lost second stromag servo drive in a one month time period. We have a number of these drives installed in our loading department of our mill. They have been reliable but about a month ago we had one of them fail, no status lights visible. Manual suggested an internal fault on the drive. We changed out the drive and the new one performed well but has recently gone belly up... same symptoms.

Looking for a possible underlying problem and wondering whether it might be a supply issue. Anyone have experience with these drives or similiar issues? Metering equipment indicates all voltage levels are where they should be.

Please offer more information about the working condition of your workshop and monitor the voltage. You know, sometimes, when you switch on a machine which shall cause a fluctuation of the voltage. In the meanwhile, if you switch on a second machine in a short period, it will cause a big shock the servo drives.

Allen,

It does seem that both times the servos faulted that it was on a Monday morning after a weekend shut down. The machine bags our product so it incorporates a number of conveyor motors and a few servo drives. The drive in question controls a fractional h.p. motor and the drive has run problem-free for approximately 8 years. It may be that we are encountering some supply voltage issues although it has not been an issue in this part of the mill before.