Dangers of applying too low voltage to a Contactor control?

Too low control voltage can cause damage of contactor, because:

1. If it happens during closing of contactor, then the closing is too slow or unfinished. However, impedance of coil is much lower in open position than in closed position.
As result, high current flows through the coil for long time and can cause burning of the coil.

2. If it happens when contactor is closed, then too low control voltage can make micro-opening of contactor.
It creates electric arc on main poles which causes fast wearing down or even welding (if frequent) of the main poles.

Publié pour:Schneider Electric Belgium