3 terminals screws can be applicable to both AC control circuits and DC control circuits.
Designed to control the movement of a mechanical part.Typically utilized in industrial control applications to automatically monitor and indicate whether the travel limits of a particular device have been exceeded.
This mechanism creates a quick change in contact state when the trip point is reached.
The distance between the trip and reset point is called the travel to reset, hysteresis, or differential. Finite travel to reset helps to avoid multiple changes of state if the object actuating the switch is subject to vibration.
The amount of travel of the contacts is also not dependent on the amount of travel by the actuator.