c)Varistors Circuit

3 Varistors Circuit

When wired parallel to a coil, Varistors, voltage-dependent resistors, limit the maximum over voltage, since they become conductive when a specific threshold voltage is exceeded



Fig. Basic circuit diagram: varistor




Fig. Switching over voltage of a contactor with varistor

Advantages : The increase in drop-out time is minimum and clamps the voltage to acceptable levels.

Disadvantages :Cost is very high




Overview of different protetion circuit





.....