Textbook Problem

Refer to the circuit shown in Figure 28–4. When the start button is pressed, the motor does not start immediately, but after a delay of 2 seconds full voltage is applied to the first part of the winding. After a delay of another 2 seconds full voltage is applied to the second half of the motor winding. Which of the following could cause the condition?

1. a. TRI timed contact is shorted.
2. b. S2 auxiliary contact is shorted.
3. c. S1 contactor coil is open.
4. d. OL-S contact is open.

FIG. 28–4 Elementary diagram of a three-step part winding motor starter.