Switchgear – full monitoring The switching devices monitor the switching strip connected in regard to actuation and interruption. They provide a potential-isolated safety relay contact for “Stop”. Switching strips with a length of up to 100 m can be connected to the switchgear. Monitoring is performed on the closed circuit current principle with an 8.2 kΩ resistor as the electrical termination. The switchgears possess three LEDs (green, yellow, red), which are used to indicate different states:
Green: switching strip connected, system ready for operation, safety contacts closed
Yellow: error message “Open sensor circuit”, safety contacts opened
Red: switching strip actuated, safety contacts opened
If, in the case of fail-safe (redundant) devices (Safety Category 3), the channels indicate a differing status; this signals a system malfunction and the safety contacts will be opened. When the switching strip is actuated, the relay will drop out and the safety contacts will be opened.