Limit Switch

A limit switch is used to limit the activation of an electrical circuit. When a circuit is “closed,” it allows the flow of electrical current through the switch to pass to the device being powered. When the switch is “open,” the switch is disengaged and no electrical power will pass through it. Whether the limit switch is open or closed is generally determined either by the position of a device being powered or by a set amount of time a device requires to complete a specific task.
The most common type of limit switch is a mechanical limit switch. This switch tracks the location of a specific item and opens or closes when that item reaches a specific location. The switch is activated by physical contact, or lack thereof. For example, a light inside a car often turns on when one of the doors is opened.