The timed relay is used to trigger a delayed action for a brief period after another action. Thermal timed relay should not be confused with timers, counters and programmers of very high precision. Timed relays are similar to other control relays in that they use a coil to control the operation of the contacts. The difference between a control relay and a delay relay is that the timed relay contacts take a set amount of time to change their contacts when the coil is energized or de-energized. Timed relays or time delay relays can be classified as either on-delay or off-delay relay.
• On-delay - When the coil of a delayed relay on-delay is energized, the contacts change the states after a predetermined time.
• Off-delay - When the coil of an off-delay timed relay is energized, the contacts immediately change the states and after a predetermined time return to the original position.
