Single-phase and 3-phase AC squirrel cage induction motors need some type of control circuit to initiate a start or stop function. The two types of ladder control circuits commonly used are the 2-wire ...

The circuit consists of a power supply, a motor, a start button, a stop button, and a relay. The relay has a coil and a set of contacts, which can be normally open (NO) or normally closed (NC).

Isolating problems in the control circuitIn Part 1 of this two-part series, we presented a 3-phase, 480VAC motor circuit with its associated controls (Figure). We stepped through a logical, systematic ...