A time switch (also called a timer switch, or simply timer) is a timer that operates an electric switch controlled by the timing mechanism. The timer may switch equipment on, off, or both, at a preset time or times, after a preset interval, or cyclically. A countdown time switch switches power, usually off, after a preset time. A cyclical timer switches equipment both on and off at preset times over a period, then repeats the cycle. Once the coil of the timer is energized the timer starts to count from zero to the pre-set time, this count is known as the accumulated time. The contacts of the timer will stay in their changed state for the same amount of time the coil is energized.