I have multiples of SCR showing up and growing after a 1000hp DC motor was rebuilt. I need to have the electronics tech to test the drive out but I do not know what to tell them to check. Any help would be appreciated. Thanks

Did the 21,600 show up after the motor was reinstalled? This vibration typically comes from SCR firing frequency. So which ever SCR's in the drive are used for this circuit, first place to look. This vibration can also come from broken field windings and loose connections in the SCR firing circuit. Would also be a good idea to recheck all electrical connections that were disturbed during the removal and reinstallation of the motor. Are you having speed fluctuations, heating of the motor or other anomolies while this motor is running?

The 21,600 has always been there but the multiples were not at the elevated magnitude. I will ask the process tech about any speed fluctuations and compare a current thermo reading with a previous one.

I'm with Dave on the connection check. I have had similar occurences which were brought on by loose wiring. The first and simplest way to check these is with thermography but a simple IR temp proble like the Raytek Mini Temp will work.

Thanks for your input. We located a possible loose connection and a bad fuse. We will try to correct those issues and see if the SCR magnitude is reduced.

I agree with Dave Reynold's analysis, I believe you have found the current problem on his advise, you mentioned that the Drive showed lower levels of 21,600 on a previous date. You may find the connections from the Firing Transformers to the Gate of the SCR may have bad connections, these are usually twisted pair cable Red and White, and sometimes push-on connectors are used and over time the heat degrades them. Possibly the Drives have been rebuilt from Analogue and a new Digital front end was added!