Here is an example of a time-delay relay contact used in a motor control circuit diagram: In this circuit, the motor delays start-up until three seconds after the switch is thrown to the “Run” position, but shall stop immediately when the switch is returned to the “Stop” position.

Time delay relays were commonly used to control the start and stop of the motors. In terms of motors, they are quite useful as when there is an outage, there is a surge of the voltage. They are also used to provide a delay before starting the motor or to provide a time delay before stopping the motor.

On- and off-delay timers represent most of the typical time delay relay timers in use. Other types include interval-on-operate, flasher, or repeat cycle timers. Normally open, on-delay timers start timing when the input voltage (power supply) is applied.

IDMT relay was an inverse definite minimum time relay. It is one in which the Time of operation is inversely proportional to the magnitude of the fault current flow near the pickup value and becomes substantially constant slightly above the pickup value of the Relay.

The relay permits a small amount of electrical current flows to control high-current loads. When voltage is supplied to the coil, a small current flow passes through the coil, resulting in a larger amount of current flow passing through the contacts to control the electrical load.