When an electrical system or device needs to be turned on or off at a certain time, a time relay is normally used. These devices find use in a broad range of electrical devices and systems, from those used in homes, commercial buildings, to industrial settings. Here’s all you need to know about time based relay switches, including their different uses.
What is a Time Delay Relay?
Also called a time-delay relay or timer relay, a time relay is a device that controls the timing of an event. It opens or closes contacts after a pre-determined amount of time has elapsed, thereby providing a timed control function.
Timed relays are used in applications where it is necessary to delay the execution of some event. These may include industrial control circuits, security systems, burglar alarms and automated lighting control systems.
Time relays can be either electromechanical or solid state and analog or digital. Although they perform one main function, these types of timer relays use different interfaces and other characteristics such as advantages and disadvantages.
An electromechanical timer or time relay uses an electromagnet to operate a set of switch contacts. The time delay is controlled by a special circuit and adjustable and using a knob or dial located on the device. These timers are rugged and can be used in a variety of industrial applications.
Solid State Time Relay
A solid state timer relay uses semiconductor components instead of moving parts to control the timing of an event. The time delay is adjustable and can be set using a potentiometer on the device. A solid state timer delay relay is small and compact, making it ideal for use in space-constrained applications.
Analog Timer Relay
An analog timer relay is an electromechanical or solid state device that uses analog inputs to control the on and off timings. It mostly comes with a dial to set the required time delay, and may allow various time ranges to be set. These time relays offer fewer settings but are simple to use.
Digital Time Relay
A digital timer relay uses a digital input to control the on and off timings. These timers usually come with LED displays or an LCD display to allow you set your time function, which may be a separate device from the relay. These types of time relays can be programmed to provide a wide range of settings, and are often multifunction deices.
What is a Time Relay Used For?
The main time relay function is to control an event based on time. The device is, therefore, used in a variety of applications that require timed sequences or intervals. These range from simple timers to complex sequence controls. Some of the most common time delay relay uses are listed below:
- Time relays are installed in buildings to turn on and off lights at specific times.
- In homes, a timed relay may be used to control a variety of appliances and systems such as the HVAC system.
- Time delay relays find extensive application in a range of industrial systems such as motor starting control, conveyer belt control, and turning on/off valves.
- In security systems these relays operate burglar alarms and other security installations.
- Telecommunication companies use timing relays to control various systems and processes.
- In the automotive industry, the time relay is employed in a number of functions such as the control of turn signals.
How Does a Time Delay Relay Work?
Let’s now see how a timer relay works. A time relay is used to control an event based on time. The time delay can be set by the user, and once it has been activated, the relay will wait the specified amount of time before executing the event.
The event can be anything that the relay is designed to do, like opening or closing a circuit, turning on or off a device, etc. Here is the timer relay working principle.
- A time relay uses an electromagnet to operate a set of contacts, or it may be a solid state time relay and use semiconductors (electronic circuitry).
- When the time relay is activated, the electromagnet is energized, and the contacts are closed.
- Once the time delay has elapsed, the relay will carry out the event and then return to its original state, waiting to be activated again.
- After a pre-determined amount of time has elapsed, the electromagnet is de-energized, and the contacts are opened.
The time relay delay is usually adjustable. There are also timed relays that allow users to set multiple functions, such as different timed events.
On-Delay Time Relay
An on-delay time delay relay is a device that turns on the load after a pre-determined amount of time has passed. The on-delay time relay is used in applications where it is necessary to turn on the load at a specific time.
For example, the relay can be used for lighting control. When the on-delay time delay relay is activated, the lights will turn on after a pre-determined amount of time has elapsed.
Off-Delay Time Relay
An off-delay time delay relay turns off the load after a pre-determined amount of time has elapsed. This mostly happens when the initiating switch is turned off, or the power to the relay is interrupted.
Some of the applications that would require an off-delay time relay are process control, security systems, and HVAC systems. In these systems, it may necessary to turn off the load at a specific time.
Multi-Function Time Relay
A multi-function time delay relay is a type of relay that can be used as an on-delay time delay relay or an off-delay time delay relay. The multi-function time delay relay has two sets of contacts: one set for on-delay operation, and one set for off-delay operation.
The multi-function time delay relay is used in applications where it is necessary to have both on-delay and off-delay functionality. For example, a multi-function time relay can be used for lighting control.
Time delay relays control events that are based on time. Because of this, time delay relays are used in a variety of applications where delayed action is necessary. And while there are many different types of time delay relays, they all serve the same purpose: to control an event based on time. We hope this article has helped you to understand the basics of time delay relays.
If the power supply of on-delay timer relay has output power drop, e.g., from 24V dropped to 12V, what will happen? Timer relay won’t be triggered? Can’t turn on the load after defined time passed, right? Or even the load will be power off eventually?