The Off Delay or delay on make timer is used for the time delay triggering function. These timers have power applied all the time. When a contact closure or voltage is made to the input terminals, the contacts will transfer and time delay will begin. At the end of timing the contacts will transfer back.
True Off Delay timers utilize a unique timing mode. These timers are triggered to begin their timing cycle when power has been lost. At the end of the time cycle the timer’s contacts will transfer. Loss of power is the method of starting the time delay cycle.