Adjusting an on-delay timer
Resource: https://www.youtube.com/watch?v=VHLeRZL9XPw
Two options stand out when selecting timing devices: on-delay and off-delay. So, how do you know which type to use? This on-delay timer vs. off-delay timer guide explains how the two products differ, their uses, and more, including common questions that first-time buyers ask.
Key Takeaways
- What is Different: One type waits to make a circuit when you apply the input signal, while the other waits to break it.
- Similarities: They both provide a timed interval before performing the desired action, whether starting or shutting down.
- When to Use Each: Use a wait-to-make timer for delayed startup and a wait-to-break type for delayed deactivation.
- How to Choose: Consider the application requirements (extended start or stop time) and the type of load or circuit.
What is an On-Delay Timer?
An on-delay timer is a timing device that introduces a preset duration before the output turns on when the input is activated. In other words, it extends the time between the input signal and the output’s actual response.
An example is a timer that prevents an electric motor from running immediately after power is applied. The wait can serve various purposes, depending on the desired outcome or application setting.
Common functions include making motor startups safer, providing a starting sequence for industrial machinery, or making sensing more accurate by extending triggers: more about these later when we compare uses.
What is an Off-Delay Timer?
This timer waits for a set duration before breaking a circuit. That means delaying the shutdown of a connected load when you apply the trigger signal. The period remains for as long as the input is active.
The delayed off is helpful when an electric circuit or device must stay on for a short duration before turning off. Examples include staircase or corridor lights, bathroom fans, and industrial conveyors.
In these applications, the wait time helps enhance safety for humans and machinery. For a deeper insight, below is a direct comparison of the two timing devices.
The wiring of an off-delay timing device
Resource: https://www.youtube.com/watch?v=yTU7EjTV778
On-Delay Timer vs. Off-Delay Timer
While they are both timers, the two devices differ in how they work and, therefore, in their purposes and specific applications. Let’s examine each of these differences to understand how to distinguish between on-delay and off-delay timers.
Timing Function
An on-delay function means the timer waits before activating the output when you trigger the input. On the other hand, off-delay prevents the output from deactivating immediately when you remove the input signal.
Timing Action
The wait-to-make type starts counting when it receives the input signal and closes its contacts when the time expires. The off-delay type likewise begins the deactivation countdown when you remove the input signal, and opens contacts when the countdown ends.
Output Response
The output of a wait-to-make timer remains on when you apply the trigger, waiting for the timed period to end before allowing (power-on). The output of the off-delay type remains on until the set time expires, and then turns off (power-off).
Power Loss
Removing the input signal of a wait-to-make timer before the set time elapses does not achieve the desired action. Instead, it resets the device. Similarly, activating the input of a wait-to-break timer before the pre-determined time resets it.
How to Choose Between an On-Delay and Off-Delay Timer
Application requirements dictate your choice. That’s because the two devices serve different purposes, as indicated earlier. Consider these factors to ensure you pick the right product for your needs.
Primary Purpose
What do you intend to use the device for? Choose a wait-to-make type when the application involves waiting before performing the desired operation. A wait-to-break type is used in applications that require a circuit to remain active for some time before breaking.
Process Requirements
The on-delay timer is a wait-to-make type. It keeps the output off for the set duration before turning it on. Use it to prevent immediate power-on or stagger startups.
Does the process involve allowing a system or equipment to cool, purging hazardous fumes, or enabling precise control of process endings? Use a wait-to-break timer.
Load Characteristics
Consider the type of load or device. Wait-to-make timers are suitable for motors, especially when sequencing or delayed starting is critical. The wait-to-break type is typically used to extend the operation of cooling and exhaust systems.
Off-delay timer wiring diagram
Resource: https://www.youtube.com/watch?v=FdQ3NHJxWY0
Real World Applications of On-Delay Timer
Soft Motor Starting:Â Allowing large motors to start at lower voltage and current levels (start) before switching to full power (delta).
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Machine Safety: For delaying the starting of electric motors and machinery that require cooling, lubrication, or other actions before they can run safely.
Operator Safety: To extend the startup time of dangerous machines or systems and ensure operators leave the room or machine proximity.
Staggered Starting: To prevent loads from starting at the same time. The wait enables the user to automate a system, prevent high inrush currents, and save energy.
Real World Applications of Off-Delay Timer
Lighting: To prevent stairway and hallway lights (or other places like warehouses) from turning off immediately for safe passage or exit.
Security Systems: For extending the warning of alarms for optimal alerting and for extending the turning off of security lights to ward off intruders or allow cameras to capture scenes.
Electric Equipment: Extending the operation of motors, pumps, fans, compressors, etc., for lubrication, cooling, or pressure stabilization.
Industrial Processes: Delaying stoppage to allow cycles to complete or ensure safety by letting systems operate briefly before shutting down.
Frequently Asked Questions
- How do you know if a timer is on or off-delay?
- A. Testing the timer by applying the trigger and observing the output confirms its type. Manufacturers also indicate the type on the product label and provide wiring schematicsthat indicate the device type.
- Can you adjust an off-delay timer?
- A. You can. However, adjustment features depend on whether the timer is analog or digital. Analog types use knobs or dials. Digital versions use tactile or touch-sensitive interfaces and buttons. You can also program them.
- Can an on-delay timer continue working after a power loss?
- A. No, it can’t. Its countdown requires the trigger to remain on. Losing power means the countdown cannot continue. The timer resets, and the required output doesn’t materialize.
- Q. Can a timer perform both on and off-delay functions?
- The answer is yes. Timers are available that offer the two timing options (and more) in a single device. We call them multifunction timers.
- Do I need special wiring for the timers?
- A. Both timers are simple devices to use. You only need to connect them to power, input, and output circuits. These connections are usually marked, making their installation straightforward.
Conclusion
On-delay and off-delay timers serve different purposes, making them suitable for different uses. It’s, therefore, crucial that buyers understand the distinguishing factors. As explained in this guide, one delays activation while the other prevents immediate deactivation.
GEYA is your one-stop source for on-delay and off-delay timers. Whether you’re looking for a home automation timer or a device for commercial or industrial use, we have a befitting choice for your applications. Visit our product section today and browse the available options.
