why large motors have to use insulation bearings? -币游国际app

prevent damage of shaft current bearing.
 

: when the motor running, the shaft ends or between the potential difference between shaft and bearing called , if through the motor frame constitute a loop on both ends of the shaft, the shaft voltage formed the shaft current. shaft current is shaft voltage through the motor shaft, bearing, stator frame or auxiliary devices constitute a closed loop. under normal circumstances, the shaft of the motor voltage is low, the lubricating oil film bearing can play a role of insulation, won't produce shaft current. but when the shaft voltage is higher, or motor starting instantaneous oil film is not stable formed, shaft voltage will make discharge breakdown shaft current loop that produces lubricating oil film. shaft current partial discharge energy release produced by high temperature, can melt the bearing inner ring and outer ring or ball on many small area, and form a groove, to produce noise, vibration, if not found in time processing will lead to bearing failure, the great influence on production. variable frequency speed regulation system of high-frequency shaft current of is the most significant feature of the bearing is produced in the inside and outside the circle of motor bearing, ball "rub garment board" rampant grooves stripes. so the motor end bearing insulation.
 

, usually take the lateral load motor bearing insulation, insulation of motor bearing various forms, generally has: "axis" by insulation bearing, motor insulation, insulation bearing chamber, the motor end cover insulation and motor bearing, insulation and insulation bearing is the most simple method.