This variant of the Time-Delay Relay operates much like the regular TDR-M, except that it is triggered by the falling edge of an input signal. When it first receives a trigger signal on one of the two input terminals, it waits for the triggal signal to go away. When this happens, it then waits for the programmed turn-on delay, then turns on its output. Then, it immediately starts the countdown for the programmed turn-off delay, and turns off. It can then only be turned on again by the input signal turning on and back off again.
Why would you want this? If you need something to happen when a device is turned off, this relay will allow you to accomplish that. The most common application is to use this connected to a vehicle's ignition, so that when the ignition is turned off, something is turned on for a fixed period of time.
This relay now has a selectable long-delay range setting, with a 30-minute maximum delay range. This can be useful if you need something to stay on longer than the standard 2-minute range.
Wiring these relays is the same as for the standard TDR and TDR-P relays, and there are positive-switching (TDR-PMF) and negative-switching (TDR-MF) versions.
|TDR-MF Time-Delay Relay Timing Diagram|