Earth fault monitors

Earth fault monitors are not compulsory for AS-i networks. But as AS-i voltage supplies are free-of-ground PELV networks, it may be necessary to detect an earth fault which, alone, most of the time has no consequences. A second earth fault occurring later on however may lead to dangerous cross-faults which may permanently switch electrical outputs. The assessment of this risk should therefore be part of the overall machine concept.
Type housing for rail mounting	Measuring principle passive	Number of signal contacts 1x (relay) 2x (relay)

Insulation monitor

Insulation fault monitors function similarly to earth fault monitors. However, the evaluation of the earth fault is carried out in a much more complex way, so that symmetrical earth faults can also be detected and signalled. The two potential-free signal contacts can be integrated in the emergency stop circuit or trigger a signalling lamp, or they can be wired onto a digital input.
Type housing for rail mounting	Measuring principle active	Number of signal contacts 2x (relay)