Duty Cycle

A duty cycle is the time that an entity spends in an active state as a fraction of the total time under consideration. The term is often used pertaining to electrical devices, e.g., switching power supplies. It is also sometimes used pertaining to living systems such as the firing of action potentials by neurons. In an electrical device, a 60% duty cycle means the power is on 60% of the time and off 40% of the time. The "on time" for a 60% duty cycle could be a fraction of a second – or for say, irrigation pumps, days – depending on how long the device's period is. Here one period is the length of time it takes for the device to go through a complete on/off cycle. The term "duty cycle" has no agreed meaning for aperiodic devices.