Skip to content 
Timer relay is the core component in the field of automation and daily life. They control the circuit precisely through pre-set time, so as to realize orderly operation, enhance work safety, and improve work efficiency.
Why Time Delay Matters in Automation
In the field of automation, precise delay control, coordinating the workflow of multiple devices, and ensuring that actions are executed in sequence are crucial for avoiding equipment damage, reducing energy waste, and maintaining process stability. And the time delay can achieve the above effect, and can prevent surge current, so that the circuit automation operation is more safe.
Key Timer Relay Functions Explained
| Type | Working Principle | Typical Applications |
|---|---|---|
| On-Delay | Circuit turns on after a preset delay once triggered | Motor start-up (avoid surge current), industrial oven preheating |
| Off-Delay | Circuit stays ON for a preset time after trigger stops | Cooling fans, elevator lights delay-off |
| One-Shot (Monostable) | Outputs a single pulse of preset duration; requires power reset to restart | Automatic packaging machine sealing, one-time actions |
| Interval Timer | Circuit turns on immediately on power and turns off after preset time | Timed ventilation, temporary equipment startup |
| Repeat Cycle (Flasher) | Cycles ON and OFF according to set period | Intermittent operations like greenhouse irrigation |
| Star-Delta Timer | Motor starts in star configuration, then switches to delta to reduce starting current | Large motor protection in factories |
| Watchdog Timer | Controller sends regular signals to reset timer; missing signal triggers system reset | System stability, automatic restart on failure |
| Multifunction Timer | Supports multiple modes: on-delay, off-delay, one-shot, etc. | Small automated production lines requiring frequent mode changes |
1 On-Delay (Delay-on-Make)
After the trigger signal is applied, the circuit will not be turned on immediately, but will be turned on after a preset delay. On-delay is suitable for scenarios such as motor start-up (to avoid surge current) or preheating of industrial ovens.
2 Off-Delay (Delay-on-Break)
When the trigger signal stops, the circuit remains in the ON state for a period of time until the preset time before it stops working. Off-delay timer relay is usually used in scenarios such as cooling fans (delay stopping after the oven is turned off) or elevator lights (stay on for a while after the doors are closed).
3 One-Shot (Monostable)
After triggering, only a single pulse with a preset length is output. If you want to restart the timer, you must first disconnect the control and then reapply the voltage. One-shot timer relay is very suitable for automatic packaging machine sealing and other one-time actions.
4 Interval Timer
When the voltage is applied, the timer will immediately connect the circuit and then disconnect immediately after the preset time. This timer relay is suitable for scenarios such as timed ventilation or temporary startup of equipment.
5 Repeat Cycle (Flasher)
Works in a cycle according to the set “on-off” period, which can realize the intermittent operation of the equipment, such as watering the greenhouse irrigation system at a set time.
6 Star-Delta Timer
By switching the motor control from star-connected to triangle-connected to control starting, the initial current is reduced, and starting the motor in this configuration will only consume one-third of the power, but the torque will also be reduced. After a period of time, the electrical shock will switch back to the star configuration, thus obtaining all the power. This relay is mainly used for the protection of large motors in factories.
7 Watchdog Timer
When the watchdog timer is working, the main controller will send signals to it at regular intervals to reset the timer. If the signal is not received within the time limit, the system is judged to be abnormal, and a reset operation is triggered, and the system is restarted from the initial state to ensure system stability.
8 Multifunction Timer Relay
It can achieve various functions like power-on delay, power-off delay, and monostable operation via mode switching, enabling flexible adaptation to diverse scenarios. It is ideal for devices requiring frequent working mode adjustments, such as process switching in small automated production lines.
Key Selection Factors When Buying Timer Relays
Load capacity: The relay contacts and the current/voltage of the connected device (such as motor, lamp) should match to avoid damaging the circuit and electrical appliances.
Accuracy requirement: Choose the corresponding relay according to the degree of strictness of the accuracy requirement.
Environmental tolerance: Choose relays with suitable temperature, humidity, dust, or vibration protection levels according to different working environments (e.g., industrial vs. domestic scenarios).
Functional compatibility: If the workflow changes frequently, choose the multi-functional model as a priority.
FAQ
Are timer relays and time delay relays the same?
A time relay and a delay relay are not exactly the same. Delay relay is an important category of time relay, which is mainly focused on realizing the delay on-off function of the circuit (such as power-on delay, power-off delay, etc.). A time relay is a broader concept, and a delay relay belongs to the category of time relays.
Can I use one multifunction relay instead of several?
Of course, but it is required that the model covers all the required functions and the load specifications match it.
How long do timer relays last?
It can usually perform more than 100,000 operations, but the specific service life depends on the load, environment, and quality of the relay when it is used.
Can timer relays handle inductive loads?
Whether a time relay can handle inductive loads depends on its own rated parameters. It can be safely handled if the inductive load is matched with the maximum switching current, voltage, and other parameters when used.
Conclusion
Understanding these 8 time relay functions is key to optimizing automation systems and everyday devices. By matching functions with requirements and considering selection factors, C-Lin’s solutions help ensure reliable and efficient operation in industrial settings or smart homes.
