When AC asynchronous motor operates under sinusoidal alternating voltage, its rotor is in sinusoidal alternating magnetic field. Due to the lamination factors such as fan-shaped punching sheets and silicon steel sheets of motor stator and rotor, as well as the existence of iron core slot and vent hole, unbalanced reluctance is caused in the magnetic circuit. When the magnetic resistance in the circumferential direction of the stator core of the motor is unbalanced, the alternating magnetic flux intersecting the shaft will be generated, resulting in alternating potential. When the motor rotates, that is, the magnetic pole rotates, the magnetic flux passing through each magnetic pole changes, and the shaft voltage is induced at both ends of the shaft, resulting in the magnetic flux of the intersecting chain with the shaft. With the rotation of the magnetic pole, the magnetic flux of the chain intersecting with the shaft changes alternately. This voltage is generated along the axial direction. If a closed circuit is formed with the bearings on both sides of the shaft, the shaft current is generated.

What safety signs should be equipped for high and low voltage distribution cabinet

1. Stop, high pressure danger.

2. Do not switch on. Someone is working. It is forbidden to switch on and the line is operated

3. "No climbing, danger of high pressure. Work here.

4. Sign board for access

5. No switching on, someone is working!

When the motor is operated with inverter power supply, the power supply voltage contains high-order harmonic components, resulting in electromagnetic induction between the end of stator winding coil, wiring part and rotating shaft, resulting in shaft voltage. The stator winding of the asynchronous motor is embedded in the stator core slot. There are distributed capacitors between the turns of the stator winding and between the stator winding and the motor base. When the general frequency converter operates at high load frequency, the common mode voltage of the inverter changes sharply, and the leakage current will be formed from the motor shell to the grounding terminal through the distributed capacitance of the motor winding. The leakage current may form radioactive and conductive electromagnetic interference. Due to the imbalance of motor magnetic circuit, electrostatic induction and common mode voltage are the causes of shaft voltage and shaft current.