An Overview of Shaft Voltages and Bearing Currents in Rotating Machines

Shaft voltages and associated “shaft currents” or “bearing currents” have been known since more than a century on DC and AC motors under classical line operation. More recently with the emergence of inverter drives, there has been an increase of high-frequencies bearing currents and shaft voltages creating mainly premature failure of bearings. Although those phenomena and the associated mitigation techniques are now well-known, one must be kept …