Whether looking for a timer for sale in your business or to use in your project, you’ll need to choose from different types of timer relays. But that can be tricky depending on your application or market. Here, we’ll go over the 5 most common types of timer relays, so you can make a decision based on the specific needs.
Time Relay Definition
A time relay is a device, usually electromechanical, that opens or closes a circuit after a preset period. Timed relays can be used to delay the energizing of a circuit, delay the de-energizing of a circuit, and perform timing in either directions or a combination of both.
The time delay can be adjustable or fixed, depending on the needs of the application. The time delay is usually adjustable using a knob, dial, multi-position switch, or other means. This allows the user to change the time delay without having to replace the entire relay.
A time delay relay can also be used to repetitively energize and de-energize a circuit at preset intervals. These types of timer relays are often used in applications such as water sprinklers, where the circuit is powered for a set period, then left without power for a set period.
Because timing needs and other requirements are different, time relays are built in a variety of different types. Here’s a look at the most common types of timer relays, their best applications, and other important information.
Types of Timer Relays
Time delay relay manufacturers make the device in a variety of sizes, operation methods, and other design variations. Most of the time, the relays will differ in the mode of operation.
Time relay operation can be either on-delay or off-delay. As the name implies, an on-delay timer will turn on after a specific time delay, while an off-delay timer will turn off after a specific time delay.
There are other types of time relays as well, such as those that are multi-functional. Based on your application needs and other factors such as price and accuracy or switching action, you can choose from the following types of timer relays.
1. On Delay Timer Relay
The on-delay time delay relay is the most common type of time relay. As the name suggests, this type of relay will start the timing action when an input voltage is applied, and energize the output after the set timing.
In order to de-energize the output, this input voltage must be removed, after which the on time delay relay will reset.
On-delay time delay relays are used in applications where it is necessary to ensure that a certain process has taken place before starting another process.
For example, you may use an on-delay timer in a conveyor belt application to make sure that the belt is up to speed before starting the next process. Other common uses of these Types of Timer Relays are:
- Blower motors where are the on delay timing relay is used to delay the blower’s startup.
- Burglar alarms that need to delay the sounding of the alarm to allow authorized persons time to leave the premises.
- In industrial systems to stagger the startup of large motors so that the power supply is not overloaded.
- To operate door locks that must wait a few seconds after the power is applied to make sure that the door is closed before locking it.
- In fan controls, the on delay timer relay is used to make sure that the fan has come up to speed before energizing the blower.
2. Off Delay Timer Relay
The off-delay time delay relay is the second most common type of time delay relay. This type of timer relay requires a trigger to start timing after it has received an input voltage. Its output will, therefore, be energized upon the application of the trigger, after which the trigger is removed so the timing can start.
After the set timing duration, the output will de-energize. The off-delay time delay relays fit into applications where it is necessary to ensure that a certain process has taken place before stopping another process.
An example is when you need to make sure a motor has cooled down before stopping it. Here are other applications that may require the use of these types of timer relays:
- Elevator doors that must close after a certain amount of time.
- Coin-operated appliances such as washers and dryers that must turn off after a certain amount of time.
- Air conditioners that must turn off after a certain amount of time has elapsed.
- In gas control systems to prevent dangerous situations such as gas leaks.
3. One Shot Timer Relay
Also called interval-on-operate time relay, the one-shot time delay relay is a type of time delay relay that triggers only once. The output when using this type of time relay is already energized when input power is applied.
The countdown, therefore, starts when the input voltage is applied, after which the output will de-energize. The operation of the one shot timer relay makes it suitable for a variety of systems and processes, including industrial ones. Here are some of the most common one shot time delay relay applications.
- Burglar alarms where the timer relay allows authorized persons time to enter rooms and deactivate the security system without the alarm sounding.
- Dispensing equipment use one shot timers to dispense the correct amounts of a product.
- In industrial applications where a machine must be started and stopped at specific times
- The one shot timer relay is also used in welding machines to allow time adjustments for spot welding.
4. Recycle Timer Relay
Also known as a repeat cycle timer, a recycle time delay relay turns on and off at regular intervals. These types of relays are often used in applications where it is required to cycle power to a device or electrical system.
One common use for repeat cycle time delay relays is in HVAC systems. In this application, the time relay turns on the compressor and then off again at regular intervals. This helps to prevent the system from overheating. The repeat cycle timer relays also find use in the following applications:
- In sprinklers to cycle the times when
- Pump controls to cycle the pump and prevent it from overheating.
- In electrical equipment systems where it is necessary to turn the device on and off at specific intervals.
5. Flasher Timer Relay
In a flasher timer relay, the contacts keep energizing and de-energizing at regular intervals. This is usually after the application of an input voltage.
These types of time delay relays are often used in applications where it is necessary to indicate that a system or process is working.
One common use for a flasher timer is in emergency lighting systems where the light must flash at regular intervals to indicate that the system is working. The flasher time delay relay is also used in the following applications:
- As an indicator in a process control system
- To indicate that a device is turned on
- In traffic signals
There are many different types of timer relays that are available on the market today. Each type of relay has its own unique set of features and benefits. Choosing the right type of time delay relay for your application will, thus, depend on what you want to use the device for. That’s because each type of time delay timing relay is designed for a specific purpose.