Timing relays:Motor-Driven Timers

Motor-Driven Timers

When a process has a definite on and off operation, or a sequence of successive operations, a motor-driven timer is generally used (Figure 7– 10 and Figure 7– 11). A typical application of a motor-driven timer is to con- trol laundry washers where the loaded motor is run for a given period in one direction, reversed, and then run in the opposite direction.

Generally, this type of timer consists of a small, synchronous motor driving a cam-dial assembly on a common shaft. A motor-driven timer successively closes and opens switch contacts, which are wired in circuits to energize control relays or contactors to achieve desired operations.