1. Overload operation of high-power motor.
When the equipment is not matched and the load power of the motor is greater than the rated power of the motor, the motor will run permanently overloaded (that is, the small horse-drawn cart), which will cause the motor to overheat.
When repairing an overheated motor, you should first find out whether the load power is consistent with the motor power to prevent the blind target from being disassembled.
2. The load of the dragged machine is abnormal. Although the equipment is matched, the load of the machine being driven is abnormal, and the load is sometimes large and sometimes small during operation. For example, when the motor is equipped with a thresher, when the feeding amount is too large, the electric timing will have a fever due to overload.
3. The dragging machine hinders. When the machine being dragged is obstructed, does not move or gets stuck, it will overload the motor and cause the motor winding to overheat.
1. The motor overheats due to its own reasons
1. The winding of the high-power motor is broken. When one phase winding of the motor winding is open, or one of the parallel branches is open, it will cause the three-phase current to be out of balance and cause the motor to overheat.
2. The motor windings are hindered by a short circuit, and the short-circuit current is much larger than the normal working current, which increases the copper loss of the winding and causes the winding to overheat or even burn.
3. The motor connection is wrong. When the delta connection motor is wrongly connected in a star shape, if the motor is still running with full load, the current flowing through the stator winding will be higher than the rated current, which will cause the motor to stop by itself. If the stoppage time is a little longer and the power supply is not cut off, the winding Not only is it severely overheated, it will also burn the motor.
When the star-connected motor is wrongly connected to form a triangle, or a motor with several coils connected in series into a branch is connected to two branches in parallel, the winding and the iron core will be overheated, and the winding will be burnt in severe cases.
4. Wiring of the motor process. When a coil, a group of coils or a phase winding is connected reversely, the city will cause serious dissatisfaction of the three-phase current, and the winding will overheat.
5. The motor is obstructed by the machine. When the motor shaft is bent, the assembly is not good, the bearing is obstructed, etc., the motor current will increase, the copper loss and the machine loss will increase, and the motor will overheat.
2. Poor ventilation and heat dissipation make the motor overheat
1. The temperature is too high and the inlet air temperature is high.
2. The air inlet is covered by sundries, which makes the air inflow difficult and causes a small air inlet.
3. Excessive dust inside the motor affects heat dissipation.
4. The electric fan is damaged or installed reversely, resulting in no wind or small air volume.
4. There is no wind hood or no wind baffle in the end cover of the motor, causing the motor to have no suitable wind path.