Reasons why the single-phase motor does not rotate and hums:(1) Single-phase operation due to power connection problems:(2) The motor is overloaded;(3) Stuck by the towing machinery;(4) The rotor circuit of the wound-rotor motor is open and disconnected;(5) The first end of the stator is connected incorrectly, or there is a broken wire or short circuit.
The solution to the problem of single-phase motor not rotating and buzzing:In the first case, you need to check the power cord, mainly the motor wiring and fuse, to see if there is any line damage;In the second case, the motor is unloaded and then started at no load or half load;
The third situation is probably due to the failure of the towed equipment. Unload the towed equipment and find the failure in the towed equipment.In the fourth case, check the engagement of each contactor including brushes, slip rings and starting resistors;In the fifth case, it is necessary to re-determine the beginning and end of the three-phase and check whether the three-phase windings are broken or short-circuited.
Measure the motor terminals. If the three-phase voltage is balanced and at the rated value, it can be judged as a serious overload. The inspection steps are: first remove the load. If the motor speed and sound are normal, it can be judged that the load is overloaded or the load mechanical part is faulty. If it still does not turn, you can turn the motor shaft by hand. If it is very tight or cannot turn, measure the three-phase current. If the three-phase current is balanced but larger than the rated value, it is possible that the mechanical part of the motor is stuck, such as the motor shaft lacks oil, the bearing is rusted or seriously damaged, the end cover or oil cover is installed too tilted, the rotor and the inner bore collide (also called sweeping the bore), etc. If you feel more laborious when turning the motor shaft to a certain angle by hand or hear a periodic "squeaking" sound, it can be judged as sweeping the bore.
The reasons are:(1) The gap between the inner and outer rings of the bearing is too large and the bearing needs to be replaced;(2) The bearing chamber (bearing hole) is too large, and long-term wear causes the inner hole diameter to be too large. Emergency measures are to electroplate a layer of metal or add a sleeve, or to punch some small dots on the wall of the bearing chamber;(3) The shaft is bent and the end cover stop is worn.
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