While there are volumes of information online about the duty cycle, it’s really a relatively simple concept. Duty cycle is simply the ratio of time a circuit is on compared to the time that the circuit is off. Our products, as with most electronic devices, have a maximum recommended duty cycle. Choosing an actuator (or any motor) that has a duty cycle appropriate for your application is an important consideration.
Why is duty cycle important?
Ensuring that you run the device at or below the max recommended duty cycle ensures that you will get the longest life possible out of your actuator. When a manufacturer rates a product for a maximum duty cycle, it is typically based on lifespan testing. If you run an actuator or electric motor at a higher than rated duty cycle, you are likely to experience premature failure. There are a number of reasons that this can happen including but not limited to:
- Premature component failure due to heat
- Premature lubricant failure
- High levels of stress on mechanical components
- Motor will reach the natural end of its life sooner
As with most electronic devices, when linear actuators run, they produce heat. If the temperature of the unit is allowed to rise beyond a certain threshold, damage to the unit is likely. If the actuator has a maximum duty cycle of 20% and you are constantly running it at 25%, you will increase the likelihood of component failure. This could be the motor, circuitry or gearbox. Duty cycles are set low enough that the temperature will not rise to the point of causing damage.
How is duty cycle calculated?
Calculating duty cycle is quite simple if your application requires that the device be run at a consistent pace. If an actuator is run for 30 seconds, and then stops running for 30 seconds, it has a 50% duty cycle because it is running 50% of the time. The duty cycle always represents the time that the actuator is ON.
We base our values on the peak efficiency point for each product. The problem is that as you increase the load on the device and the speed at which it's traveling, you decrease your duty cycle as the actuator creates more heat. Conversely, if you run a lower load or a slower speed than the peak efficiency point, then your duty cycle will go up.
What factors can affect duty cycle?
As mentioned, duty cycle ratings are calculated at peak efficiency. If you’re operating your device at peak efficiency, the rated duty cycle will be appropriate. There are however a number of environmental and other factors that can affect the duty cycle, and these factors, combined with application testing, should be used to determine the appropriate duty cycle in your application.
Some key factors to consider that can affect the duty cycle of your device are.
Other operating conditions can affect the duty cycle as well. Humidity levels and side load will also have an impact on the duty cycle of any electric motor or actuator. If you need a higher-duty cycle, you can buy a device with a higher peak efficiency point. This means that even if the duty cycle is the same, you'll be running below that number and you will get more life out of your device.
What happens if a device is run past its duty cycle?
Running any electronic component at a higher duty cycle than it is rated for is not advised as it will almost always reduce the lifespan of the device. For actuators specifically, this can be due to wear caused by extra heat generated by the motor and gearbox assembly.
Duty Cycle Conclusion
Understanding the concept of a duty cycle is essential for anyone working with actuators and electronics. By grasping the duty cycle, you can make informed decisions about design, maintenance, and performance.