The high voltage rate-of-rise and the resulting voltage spikes at the motor terminals, increase the voltage stress at the motor winding in comparison to direct line operation. In conjunction with the connected cable capacitances, the motor reactors reduce the capacitive charge/discharge currents in the motor cables and, as a function of the motor cable length, limit the voltage rate-of-rise dv/dt and the voltage spikes Vpp at the motor terminals.
引自-《SINAMICS 工程师手册》
说明：那个图上Vmotor说的是在电机（定子绕组）端产生的。并且是变频器电机出线下方的PE端和电机外壳可靠连接为前提（这点是消除这类报警首先要做的！一拖多往往不好处理这个问题。它造成的电压偏离N，引起故障不在少数！）。
这就是为什么上次我问电机电缆过短有什么坏处的原因。