The operating principle of a float switch based on reed contact utilizes a reed contact as the switching element. A float switch consists of a buoyant body, also known as the float, which floats on the liquid surface. The buoyant body is equipped with a magnet.

As the liquid level changes, the float moves up or down accordingly. When the liquid reaches a specific level, the magnet approaches the reed contact. The reed contact comprises two ferromagnetic contact blades housed within a glass capsule, separated by a small air gap. When the magnet from the float nears the reed contact, its magnetic field pulls the ferromagnetic blades together, closing the circuit.

This closed circuit can be used to send a signal, such as triggering an alarm or controlling a motor.

Level control refers to the float switch’s ability to maintain the liquid level within a specific range or initiate specific actions when the level reaches predefined thresholds.