GE DC300 Drive-Field Shunt Fuses Keep Popping

Any response would of course, require some sort of guess work on the part of the responder. That (my disclaimer) being said, I would not recommend removing your field shunts else the motor could be impossible to control or start.

If you have already successfully operated this "press bolster" (what ever that is) for a few weeks then you need to be asking the question "What changed?". If the environment is full of conductive dust there could be some short circuit activity.

If there is excessive vibration, you could have excessive wear and tear. You might have to remove a motor and disassemble it to look for signs of wear or scraping. After only a few weeks the motor should still look new. You might have to look very carefully because the fuse is saving you from motor failure.

If you put larger (higher amperage) fuses in, the problem will become more obvious but you will also probably render the motor unusable. You will need a spare to put in while the damaged motor is out for re-winding (new wire). Chances are that something has not been properly matched to the task and you will need a larger or more robust motor instead of the little one. You can also check with the tech. support for the manufacturer of the motor. I'm sure they see all kinds of failure modes...

I know the motor will not function without the field shunts- there will be absolutely no magnetic field in the windings. I was merely stating the fact that with that circuit physically removed there is no popping of fuses or fault codes generated, telling me the issue is with the scr/shunt circuit.

This 'press bolster' is a moveable platform for a press die- there are two per press, they allow the changing/modification of dies while the press is still active. This system is from 1985 and was recently relocated to the location I am currently working on it. The drive system, shunts, motors, all have worked as a system for years without issue, which is why this problem is not only frustrating but extremely hard to pinpoint. The motors, bolsters, all related hardware with the drive (minus the field wiring) is original. I have checked all field wiring for shorts and visually inspected the entire system a few times over now.

I appreciate the input.

I was thinking about the buildup of particles from the brushes inside the motor. It may be that a good cleaning of the motors may help. The conductive dust from the brushes gets on every part of the motor and with time may provide a short circuit path inside the motor. If you have a new spare motor, you could try swapping out to narrow down the search. At this point, I'll bow out and let someone else take a shot at advice for you. Good luck!