A Timer Relay is a control relay with a time delay function built in. They serve as a combination of an electromechanical output relay and a control circuit. Relays can be opened or closed normally and can be used to delay timed functions from milliseconds to hours or even days.
The difference between the timer relay and electromechanical relay is what makes the output contacts open or close. On a control relay, the contacts are opened/closed when a voltage is applied and removed from the coil. However, for timer relays, the contacts will open/close before/after an intentional time period.
For timer relays, there are several types of timing functions each with its own unique capabilities and application.
Listed here are some of the more common types of timing functions in timer relays:
On Delay relay - Starts the delay timer upon the application of voltage. For instance, in vehicles, a on delay relay is used in a glow plug relay, the delay time begins when voltage is applied to the plugs.
Off Delay relay - This relay starts the delay timer when voltage is removed from the circuit. In air conditioners, the off delay relay may allow fans to continue running for a specific time period even after the cooling compressor has shut off.
Single Shot timer relay - A one-time delay is activated when voltage is applied to the circuit, and they can be useful in automation signalling such as fire alarms when a light needs to be on for a certain amount of time before it switches off.
Interval On timer relay and Flasher (On First / Off First) timer relay - Often used to create regular timing intervals, this type of relay can be used for applications such as blinkers.
Repeat Cycle timer relay - Delay timer is started once voltage is applied to the circuit and this timer restarts when the delay time is finished. Repeat cycle timer relay is used in applications like sprinklers.
When it comes to voltage rating, for timer relays with a voltage around 12V, they are commonly used in smaller electronic devices, where low voltage is required. Timer relays with a voltage near 220V are used in industrial and commercial settings where higher voltage is needed to operate large equipment.
Refer to RS Timer Relays Guide for more information on timer relays.
Time Delay Relays are typically used in industrial applications and OEM equipment play an important role for many industrial processes such as small panel or sub-panels requirements.
Lighting circuits
Motor start control
Sensitive equipment
Safety control
Conveyor belt sequence delay
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