Inverter driven induction motor bearing current solutions

Bearing currents in induction motors can result in premature bearing failure. In this paper, the sources of sine wave and inverter driven motor bearing currents and the potential current paths are identified. These current paths are shown to flow through what are commonly considered to be electrical insulators. Currents also are shown to flow through driven equipment. Potential current paths are identified and methods to break these current paths through motor (and installation) modifications are presented. Methods to shunt these currents away from the motor or driven equipment bearings through improved high frequency grounding are also discussed. Identification of current paths through field measurements is discussed along with example waveforms. Finally, bearing current remediation methods are discussed for each identified current path and source.