Identifying and getting to root cause of shaft currents
Shaft currents have always been a concern for large motors due to magnetic asymmetries within the motor. Manufacturers strive to keep these to a minimum.
With the widespread use of Variable Frequency Drives (VFDs), shaft current issues have become a concern in all sizes of motors. If these currents are discharged through the bearings, electrical discharge machining (EDM) occurs. Proper installation of VFDs can play a large part in mitigating issues with shaft currents.