Operating principle and connection to safety control units

The continuity of the sensitive elements is monitored by checking the electrical continuity between the conductors respectively white-green and brown-yellow.

If an interruption occurs between the white-green and/or brown-white conductors, the safety control unit reacts by opening the contacts of the safety relays (which are normally closed).

The sensitive element behaves like a normally open contact. The pressure of the sensitive element causes a closing of the contact with consequent closure of the circuit between all 4 conductors.

It is possible to put multiple elements in cascade, using the following scheme.