If the fault is burning coil, mainly due to over-current caused, sometimes too high or too low voltage will cause the coil heat short-circuit, so first check the running voltage and rated voltage difference is not too much.
Over-current short circuit, there may be several reasons:
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A. Overload operation of the equipment, so that the motor for a long time at rated current or over rated current operation. In particular, the starting current of the motor is 3-5 times the rated current, so you should try to avoid starting the device with load or full load operation (mainly depends on the motor rated current and normal operating current matching margin)
B, the motor work in a more humid working environment. Before the motor starts to check the coil insulation and phase-to-ground insulation, the use of different voltage insulation requirements are different, you can refer to the relevant national standards. During the operation of the motor should pay attention to the motor waterproof and moisture.
C, pump mechanical failure caused by motor overload, the current is too large and burn coil.
D, the heat of the motor problems. General motor coil are air-cooled shell, submersible pump is water-cooled housing. Large-scale use of air-to-air heat exchanger, air-water heat exchanger cooling. If the cooling water (air), so that the coil can not heat, may burn coil.
2. The actual use of lift below the pump nameplate lift too much;
Centrifugal pump head is used to overcome the height and resistance, high-lift pump in the high-lift point of his work flow is the design point of the flow, if the work in low head, the equivalent of pump outlet resistance decreases, Centrifugal pump flow will increase, the motor will be overloaded, over to a certain extent, will burn the motor.
For example, a feed pump has a head of 50 m and a flow rate of 50 m³ / h. When it feeds water at 50 m, its flow rate is 50 m³ / hr. When it feeds water at 40 m, Its height and resistance to reduce its flow rate may reach 80-90 cubic meters / hour or more, when the motor will heat or burn.
3. Fire water pump work time is too long.
4. With load start can cause motor damage.