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How to Calculate a Duty Cycle

A refrigerator is an example of a machine that has a duty cycle.

Many electrical devices do not operate continuously but instead have a discrete amount of time during which they are active and then a certain amount of time when they are inactive. The duty cycle of a machine is defined as being a quantitative measure how long a machine is on relative to how long it is off. The duty cycle of a machine can be calculated using a very simple formula and a calculator.

Use the timer to determine the length of time the machine is switched on. Take a note of this value. For example, a refrigerator pump may be on for approximately 30 minutes.

Time the period in which the machine is switched off. Take a note of this value. Following the example, a refrigerator pump may be off for approximately 10 minutes.

Calculate the duty cycle using the following formula:

Duty Cycle = 100 * (Time on ) / (Time on + Time off)

Following the example leads to a duty cycle of:

Duty Cycle = (30 minutes) / (30 + 10 minutes) = 30/40 = 75 %

Things You Will Need

  • Timer
  • Calculator

Things You Will Need

  • Timer
  • Calculator

About the Author

Samuel Markings has been writing for scientific publications for more than 10 years, and has published articles in journals such as "Nature." He is an expert in solid-state physics, and during the day is a researcher at a Russell Group U.K. university.

Photo Credits

  • John Early/iStock/Getty Images
  • John Early/iStock/Getty Images