In automatic control systems, time-delay relays are one of the basic components for building complex logic. For example, in security systems, when the access control system is illegally opened, the relay can first delay triggering the local alarm (such as sound and light prompts). If the alarm is not lifted during the delay period, the remote alarm will be activated (such as sending a signal to the monitoring center), leaving room for on-site processing. In water tank level control, when the water level is lower than the lower limit, the relay will delay starting the water pump (to avoid frequent starting and stopping of the water pump due to short-term fluctuations in the water level). After the water level reaches the upper limit, the water pump will be delayed and shut down to ensure sufficient water supply and avoid idling of the water pump.
