The Relay does not operate even when voltage is applied. Why is this?

The following causes are probable.

1. Disconnected Coil 

Ultrasonic cleaning or applying an overvoltage may cause the coil to become disconnected.

2. Insufficient Coil Voltage

Check the voltage being applied to the coil. The Relay will not operate if the voltage is lower than the must-operate voltage.

3. Incorrect Polarity of Applied Voltage

A Relay equipped with a diode that absorbs coil counter-electromotive force will not operate properly if the positive and negative voltages applied to the coil are connected incorrectly.