Time delay relays are control relays with a built-in time delay. Their purpose is to control an event based on time. The difference between time delay relays and other relays is when the output contacts open and close: it happens on a control relay when voltage is removed or applied to the coil; contacts on time delay relays can open or close before or after some time elapses. PoOnHand is an excellent resource for locating all types of relays, including power relays and solid state relays.
