Burn two new motors in a row! The output current and voltage of the inverter are balanced, the input voltage is balanced, the current is unstable, and the fluctuation is 20%-50%, the inverter is burned off by a short circuit between 35Hz turns, the grid voltage is very stable, 720V, the interval between the motor and the inverter is 120m, and the input and output terminals of the inverter are equipped with reactors. The motor current is very small, and the ambient temperature is about -10 degrees, which can rule out the cause of motor overheating. What could be the cause of motor failure in this situation?
Analysis of the reason: the current of the load motor is not large, it is caused by the inverter, the inverter is too far away from the motor, and the harmonic of the output current of the inverter breaks down the insulation between the smashing rooms, resulting in a short circuit, and the quality of the current and voltage on the motor side can be measured with an oscilloscope.
The cable is long, and there is a certain distribution capacitance between the ground and the earth, which will affect the propagation of electricity, so that a certain phase shift occurs between the current and the voltage, which will make the high voltage and high voltage breakdown of the motor winding (the spike, the oscilloscope can be seen, but the general multimeter cannot be seen).
Solution: If the withstand voltage is not enough to burn the motor, you can use an inverter with international certification (CE, UL) + a suitable reactor to avoid such a problem.
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