In normal operation, the motor is overheated for the following reasons: voltage is too high or too low, overload, insufficient cooling air volume, motor failure.
Collector ring burnout and brush jump spark
The main difference between the winding machine and the squirrel-cage motor is that the three end wires of the winding of the winding machine are connected to three copper or steel slip rings mounted on the rotating shaft, and are connected to the external circuit through a brush. This unique structure of the winding machine leads to the occurrence of the occurrence of the collector ring burnout and the brush jump spark. Generally speaking, the reason for this situation is that the brush and the collector ring are not well meshed, the brush cannot fully contact the surface of the collector ring, the brush and the brush box are not well matched (too loose or too tight), and the brush The pressure is not suitable, the number of brushes is unreasonable, and the collector ring is elliptical.
If the contact area between the brush and the surface of the collector ring is less than 70%, the brush having a good contact surface has a large amount of current flowing, and the amount of heat is large, which is prone to burnt and burned. Further increase the load of other brushes, in severe cases, it will burn out the phase brush and damage the slip ring. Therefore, when routine maintenance of the winding machine, special attention should be paid to whether the contact area between the brush and the collector ring is intact. When the brush production batch used is different, the brush and the collector ring may be damaged due to the difference in the composition ratio of the brush. Therefore, the same production batch should be used when replacing the brush.
The overheating of the wound motor caused by the high or low power supply voltage rarely occurs, and the motor overheating caused by the fault of the motor itself can be checked by the change of the running current and the motor protection device. Motor overheating due to insufficient cooling air volume is the most common cause. The winding motor cooling air is generated by the fan mounted on the motor shaft as the motor rotates, and is blown to the motor winding through the air passage at the top of the motor housing, thereby achieving the purpose of cooling the motor. Due to the relatively large dust on the slag powder production site, after years of operation, it is easy to cause air duct blockage. Therefore, the air duct of the winding machine should be flushed and cleaned regularly.
In addition, when the brush and the brush box are too loose, it is easy to cause the brush to jump in the brush box to generate sparks; when it is too tight, the amount of movement of the brush in the brush box is too small, and it is easy to be stuck and the collector ring is overheated. damage. When the brush pressure is small, the brush is easy to jump and sparks; when the pressure is too large, the friction between the brush and the collector ring increases, and it is easy to overheat and cause the collector ring to be damaged.
In summary, due to the structural characteristics of the winding machine itself, it is necessary to carry out targeted repair and maintenance in use to ensure the normal and stable operation of the production equipment.