quick motor check?

[Knobhead]

The first GEC Kramer drives I worked on were installed in 63.

The one that failed was about 90 again GEC designed.
They had had failures before, non with such spectacular aftermath. Swapped the pack out and switched back to speed control, no problem.
Tested the thyristor in the shop, no fault found?

Got admit one of the beauties of the Kramer system is being able to switch seamlessly from one setup to the other. It’s a bit weird knowing that the drive you’re safely working on, the motor is still running.

 

[Besoeker]

The first GEC Kramer drives I worked on were installed in 63.

The one that failed was about 90 again GEC designed.
They had had failures before, non with such spectacular aftermath. Swapped the pack out and switched back to speed control, no problem.
Tested the thyristor in the shop, no fault found?

Got admit one of the beauties of the Kramer system is being able to switch seamlessly from one setup to the other. It’s a bit weird knowing that the drive you’re safely working on, the motor is still running.

Yes, bypass operation comes more or less as a freebie.
Working on the drive while it is bypass is a feature we have built in to a few with padlockable isolation switches.
But with current site safety requirements it would need something like an act of Parliament to do so.

On thyristor failures, my experience is that, for the most part, the failure is a short circuit which can usually be measured using a standard multimeter. However, I have come across a few that weren't. Pressure mounted devices, disc, hockey-puk and various other names depend on being clamped to make internal contact may look open circuit when not correctly clamped.

I've also had a few that went into degraded mode that not dead checks would pick up.
Sometimes I'd get the chip out to try to determine cause of failure*
Here's one I did earlier

It's a 60mm diameter chip.

Around the 9 o'clock position you can see an aberration near the edge. Over voltage most likely. It helps with design parameters.

*Do not do this at home or anywhere else. Many have toxic beryllium compounds. So don't even attempt it.