I am monitoring 3 Condensate Pump motors (VFD's) that have been experiencing premature bearing failures due to shaft currents. I have recently obtained a "shaft whisker" probe to measure and trend AC - DC current from shaft to ground. I am using CSI RBMWare and a 2130 data collector to collect these measurements. Hoping someone can tell me how to setup the measurement points (AP Sets) to collect these measurements. All responses will be greatly appreciated - Thanks, Mike

This isn’t a very technical answer, but maybe it will help you get started. Sometimes trial and error leads to positive results.
It’s been a long time since I used one of those things. I think it can be used on DC Voltage Static or Dynamic. I used one for checking shaft voltages and found it difficult to determine any type of warning level. Viewing the reading in a spectral format you will either see something or you will not. I would review several motors comparing spectral information. To me the ones with issues always appeared with spikes different than normal. The spikes were always linked back to some component of the motor. You’ll know it when you see one. However, the voltages might be much lower than you would think. I remember one confirmed case I have where the shaft Dynamic overall voltage was never over 16 to 20 volts using a 2120 and 800 millivolts using a fluke.

Please find attached an application paper on the shaft probe by CSI.

ANSVC_ShaftVoltProbe.pdf (299 Kb, 31 downloads)

Normally I'll make a check with a fluke meter and measure AC, DC, ohm and hope I don't find anything. Cut a peice of welding lead and make a brush ~0.75" long and stick the probe in the other end. But if you have the CSI probe and software, use it. Or any other. In acceleration you'll sometimes notice a side blip ~1.2 Hz away from 60 Hz - always investigate.