What is On Delay Timer? On Delay Timer is a timer that delays or takes some time to get turned on or change its contact. On Delay implies Delayed On. For example, if we set 10 minutes at the on delay timer then it will change its NC contact into NO and NO contact into NC after 10 minutes of providing power supply. On Delay Timer is very important and it is very useful if you want to turn on any device or start any electrical motor with a delay time. A basic On Delay Timer has a total of five terminals. Among these two terminals for the coil that are generally named as A1 and A2. The other three terminals are Common, Normally Closed(NC), and Normally Open(NO). What is Off Delay Timer? Off Delay Timer is a timer that gets turned off or changes its contact after a preset time. Off Delay implies Delayed Off. For example, we have set 10 minutes on the off delay timer. Now we applied a power supply to its coil for up to one minute only. But the timer will change its contacts after 10 minutes of turning off the power supply although we removed the power supply after 1 minute. A basic off delay timer has a total of five terminals. Among those two terminals are for the coil that are named as A1 and A2. The other three terminals are Common, Normally Closed(NC), and Normally Open(NO). Off Delay Timer can be used where automatically turned off required for any devices or machine such as an electrical motor.