What is the purpose of bearing insulation in motors or generators?

Bearing insulation is required to prevent circulating rotor currents which can damage bearings. Our

practice is to insulate the non-drive end shaft bearing journal with a ceramic (aluminum oxide) or use

hybrid ceramic bearings. Insulated bearings are produced with the outer diameter insulated or

the innner diameter insulated. Insulated bearings are provided as standard on the following products:

• a) All 6-pole motors
• b) Vertical motors 5800 frame and larger
• c) Horizontal motors 6800 frame and larger
• d) Motors for inverter duty applications
• e) Sleeve bearing motors