High Frequency Attenuating Cable for Protection of Low-Voltage AC Motors Fed by PWM Inverters

Variable or adjustable speed drives generate pulse width modulated waveforms with risetimes below 100 ns. These very rapid transitions can cause large turn-to-turn voltages in inductive devices such as random wound motors, resulting in partial discharge and premature failure. One way to mitigate this problem is to absorb high frequency energy in the cable between the drive electronics and the motor. This contribution analyses design considerations for optimization of such a cable.