How can I prevent re‑activation for a defined time after switch‑off?

A re‑activation lockout ensures that a load cannot be switched on again for a defined time after being switched off, even if further impulses are present. Typical applications include device protection, limiting switching frequency or enforcing minimum off‑times. This function can be implemented easily using two time relays, without any special functions.

Example with 2× CIM1/UC24–240 V

Requirement

A pulse switches the load on.
The load must remain switched on for 15 min.
After that, the input must be locked for 2 h.

Time relay settings

Relay 1 (R1): CIM1/UC24–240 V
Function: Off‑delay (A)
Time: 15 min

Relay 2 (R2): CIM1/UC24–240 V
Function: Off‑pulse (N)
Time: 2 h

Operation

When time relay R1 receives a pulse at input B1, its contact 15/18 closes and starts the off‑delay (A).
The load is switched on and remains active for 15 min.
At the same time, a continuous signal is applied to input B1 of the second time relay R2 via the closed contact of R1.
After the 15 min have elapsed, contact 15/18 of R1 opens again.
This falling edge triggers the off‑pulse (N) function on R2.
The normally closed contact of R2 interrupts the supply of R1 for 2 h.
During this time, R1 is blocked and cannot switch again.
Incoming impulses have no effect.
After the 2 h have elapsed, the contact of R2 closes again.
R1 is released and the system is ready for the next cycle.