When the operating coil of a contactor is energised, the inrush current produces a voltage drop in the control circuit cable caused by the resistance of the conductors, which can adversely affect closing of the contactor.
An excessive voltage drop in the control supply cables both ac and dc can lead to non closure of the contactor poles or even destruction of the coil due to overheating, this phenomenon is aggravated by:
●A long time line;
●A low control circuit voltage;
●A cable with a small CSA;
●A high inrush power drawn by the coil;