Time Delay Relay

Understanding the differences between various time delay relay operations might be a bit confusing.   This simple overview about the three most used time relay should make it easier to visualize what’s happening during the timer operation.

Overview time relays - time relay

Overview time relays

On Delay time relay (TON)

  • The contacts switch after a predefined time.
  • The relay coil must be energized until the switching time.

Off Delay time relay (TOF)

  • The contacts switch immediately when the coil is energized
  • You return to the initial position after a preset time or when the coil is deactivated


Work order

Learnchannel TV - time relay

The entrance doors of a building should open automatically when approaching, then remain open for 10 seconds and close again automatically. An optical sensor should be used.. For this purpose, develop the pneumatic circuit diagram and the associated electrical control circuit!!