抄録
The output voltage waveform of PWM inverter to use for the adjustable speed drive of the motor is the voltage which the pulse widths differ. When surge voltage of PWM inverter is applied to the motor, the surge voltage propagates in the motor winding. The propagation of surge voltage in the motor winding differs with the propagation in the cable, because interturn capacitance is much larger than ground capacitance. In case of the steep-fronted inverter voltage, the larger voltage is developed in the interturn and it might cause the interturn insulation breakdown of stator winding, which often leads to earth insulation failure. This paper states about the result of calculation and measurement for 600kW measurement motor to examine for the surge voltage propagation in the motor winding.
