Solving Bearing Current Problems in AC Motors Numerous bearing current technical papers have been published over the last 10 years. This report does not address the sources of bearing currents in great detail, but rather provides an overview of the problem with practical solutions. What causes bearing currents? There are two chief sources of shaft voltage in an induction motor: An electrostatic charge introduced from outside the motor and electromagnetic unbalance within the motor itself. Whenever an induction motor’s electromagnetic circuit becomes unbalanced, a stray flux path will link the stator and rotor across the air gap. This flux linkage will induce a stray voltage (