Understanding Duty Cycle

In your search for the right actuator, you may be wondering what is the duty cycle of an electric actuator and how does it affect your application? When selecting an linear actuator, its duty cycle becomes important when you run the risk of making the actuator operate beyond its intended purpose.

What is the duty cycle of an electric linear actuator?

Duty cycle is the ratio of opening time to closing time, usually expressed as a percentage. If an Antuator electric linear actuator extends and retracts for 2 minutes and then takes a further 18 minutes to rest before repeating the process, then the duty cycle would be expressed as 10%.

Duty cycle is an easy calculation:

D=X/Y

D is duty cycle
X is the amount of time the component is running.
Y is the total amount of time it takes for the actuator to complete one cycle.
If our actuator extends for 97 seconds, retracts for 45 seconds and finally rests for 79 seconds, the equation would look like:

97+45=142

97+45+79=221

D=142/221=0.64

Duty cycle becomes 64%. ‘On’ time is 64% and ‘off’ time is 36%.

Why is duty cycle important?

As with most electronic equipment, when electric actuators operate they generate heat. If too much heat is released, components can be damaged. The amount of heat allowed is determined by the component with the lowest allowable temperature. If the actuator has a 20% duty cycle and you run it at 20% all the time, this can cause damage to components such as motors, circuits or gearboxes. It is not recommended that electric actuators run continuously at their maximum duty cycle, and with a lower duty cycle setting, the temperature will not rise to the point of causing damage.

When the set duty cycle has not yet exceeded the critical value of the electric actuator, then the duty cycle of the electric actuator can be increased by reducing the load and speed, and conversely its duty cycle can be reduced by increasing the load and speed.

As the load on the equipment increases and its travel speed increases, the duty cycle of the electric actuator decreases as it generates more heat. Conversely, if the operating load is below the peak efficiency point or speed, the duty cycle will rise.

Other operating conditions can also affect duty cycles, such as humidity, temperature and side loading can also have an effect on the duty cycle of the motor or actuator.