PILZ safety relay is a small current control of the current relay, it has a small and perfect control system and controlled system, so easy to operate, flexible use, ensure the safety of automatic regulation, safety protection, conversion circuit and other functions. The principle of PILZ safety relay is that when powered on, there is a constant voltage at both ends of the coil, so a current flows through the coil, thus generating electromagnetic induction. Under the action of the electromagnetic force, the armature will draw to the iron core, driving the normally open contact to draw and the normally closed contact to break. On the contrary, when the coil power, electromagnetic suction will disappear, so in the spring reaction force armature return to the original position, the normally closed contact closed, normally open contact disconnected, so as to achieve safety protection.