The phenomenon is because the magnetic flux of the fan machine is not enough. The induced current is reduced. The normal method is to replace the three-phase magnet of the fan. In exchange for greater magnetic flux. The power can be turned around because when the input current is 0, the magnetic flux is also zero.
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Therefore, there is no magnetic power and free rotation to oil bearing oil asbestos refueling, in the bar bearing clean, OK no electrified rotor free rotation, indicating that it is not holding the shaft; When the rotor is stuck and buzzing, it should be a problem with the position of the phase-shifting carbon brush inside the motor or serious wear and poor contact, resulting in the rotor coil can not shift the phase (be sucked).
The rotor of the electric fan motor is not magnetic, because the motor is an AC asynchronous motor, the rotor is composed of an iron core and the winding in the groove, and it is not magnetic when it is not powered on.
When the electric fan motor is energized, the stator winding generates a rotating magnetic field to cut the rotor winding, then there is a magnetic field on the rotor core, forming the rotor magnetic field, and the rotor will rotate and output mechanical energy.
The rotor of the electric fan motor is an ordinary iron core, which is non-magnetic. It's not a rotor made of permanent magnets.