A Motor Control Circuit ( Part 3 )

A motor control circuit (Part 1), (Part 2)

Checking Pushbuttons (Start and Stop)

Check from L1, to the side of the coil connected to L2 trough the overload contacts. If 240 volts is measured, the control circuit is complete and the contacts of the magnetic starter should be closed. See figure below.

Checking for Defective Coil

Measure the voltage from L1 to the side of the coil being supplied from L1. If a voltage reading is not obtained, the coil is bad and must be replaced. See figure below.

Checking Pushbuttons with Ohmmeter

Pushbuttons can be check for proper continuity with an ohmmeter. The stop buttons have normally closed contacts and resistance when read. Place one of the ohmmeter probes on one side of the stop button and the other probe on the other side of the stop button. If the contacts are closed, the ohmmeter needle will peg. See figure bellow.