Why does the motor generate shaft current?

The current in the motor shaft-bearing seat-base loop is called shaft current.
Causes of shaft current:
(1) Asymmetric magnetic field;
(2) Harmonics in the power supply current;
(3) Poor manufacturing and installation, uneven air gap due to rotor eccentricity;
(4) There is a gap between the two semicircles of the detachable stator core;
(5) The number of pieces of the fan-shaped stator core is not selected appropriately.

Hazards:
The motor bearing surface or ball is corroded, forming point-like micropores, which deteriorates the bearing operation performance, increases friction loss and heat, and eventually causes the bearing to burn out.
Prevention:
(1) Eliminate pulsating magnetic flux and power supply harmonics (such as installing an AC reactor on the output side of the inverter);
(2) When designing the motor, insulate the bearing seat and base of the sliding bearing, and the outer ring and end cover of the rolling bearing.