High quality and cheap induction motor, welcome to inquire, stable delivery time, when we encounter the motor assembly quality is poor, the iron core is not aligned, fixed rotor core axial gap caused by axial magnetic tension, air gap assembly and adjustment is not uniform.As the insulation level of the motor increases continuously, the allowable temperature rise limit also increases, so the higher temperature rise of the motor shell may be normal.However, it is necessary to test the temperature rise of the housing and bearing of the department with an alcohol thermometer, and confirm that the motor is overheated after comparing with the temperature rise allowed by the insulation grade of the motor, then it can be checked by the following steps.
1) Firstly, check whether the voltage of the three-phase power supply is balanced and whether the degree of voltage fluctuation is greater than the guaranteed value of the manufacturing plant (±10[%]).Due to voltage imbalance, three-phase unbalanced current is generated, which causes motor loss increase and motor heating, so it should be corrected in time.The variation of power frequency also has an influence on the heating of (±5[%]) motor, but the actual variation is not big, so it is generally not considered in the analysis.
2) Check whether the motor operates single-phase, whether the contact of the three-phase contactor is in good contact, whether the fuse of the switch has one-phase burn off, and whether the wiring is disconnected (single-phase).Troubleshoot after the fault is found.
3) Check whether the three-phase current exceeds the rated value.If the rating is exceeded, check the cause.When dealing with this kind of fault, to find out the cause of the clearance: (1) shaft bending;Bearing failure.A slight core bore does not affect the normal operation of the motor. When the bore is badly swept, a turning tool can be used to gently cut the surface of the rotor for one layer (generally turning diameter is 0.2mm or so is appropriate).
4) Dust insulation affects the heat dissipation of the motor, filter screen blockage, ventilation duct and ventilation duct blockage, etc., will cause motor overheating.Therefore, it is possible to take air cleaning measures to eliminate dust. If necessary, the motor should be disassembled for cleaning treatment.
5) If the winding is considered to be faulty, the winding short-circuit and grounding test can be conducted.According to the experience, if there is a short circuit between turns in the motor winding, the motor will vibrate, and it will smoke after a short time.However, the chance of motor heating caused by inter-turn short circuit and lasting for a long time is very rare.
The temperature rise of the motor after rewinding overhaul may be caused by problems such as poor insulation processing technology, incorrect coil data, wiring errors and assembly quality.At this time the motor should be disassembled against the original record check, and to find out the correctness of the winding data.
