A switch that limits the activation of an electrical circuit is a limit switch. Switches can control the flow of electrical current by opening and closing. When a circuit is closed, it allows electrical current to flow to the device that is powered. When open, the electrical flow stops.
In most cases, a limit switch opens and closes based on a device's position. It is often linked to timing as well. In manufacturing, a limit switch may open and turn off a device that doesn't complete a task in a specific amount of time.
The most common switches, mechanical limit switches keep track of items. When a device, or part of a device, reaches a certain location, its limit switch opens or closes. The switch depends on physical contact, or the lack of it, to open or close. An example is refrigerator light that switches off when the door closes and turns on when it opens.
A centrifugal limit switch is activated by the speed of the device it monitors. It is often a safety feature, shutting down the device if it exceeds a set speed. In industrial settings, it helps to control assembly lines, industrial robots and fire safety doors.