The current in the motor's shaft - bearing housing - base circuit is called shaft current.
Shaft current is generated because of.
(1) magnetic field asymmetry.
(2) harmonics in the supply current.
(3) poor manufacturing and installation, uneven air gap due to rotor eccentricity.
(4) detachable stator core with gaps between the two semicircles.
(5) there is a sector stacked stator core of the number of pieces of patchwork selection is not appropriate.
Hazards.
Make the motor bearing surface or ball erosion, shape course point microporous, so that the bearing running performance deterioration, friction loss and heat generation increase, and eventually cause bearing burn.
Prevention.
(1) eliminate pulsating flux and power harmonics (such as the addition of AC reactor on the output side of the inverter).
(2) motor design, the sliding bearing seat and base insulation, rolling bearing outer ring and end cover insulation.
Please check from the electric motor manufacturer TELO MOTOR to get more information about electric motor ;