Wiring Category 4

A single fault will not lead to the loss of the safety function. The single fault is detected at or before the next demand on the safety function. If this detection is not possible, then an accumulation of undetected faults shall not lead to the loss of the safety function.

To meet the requirement for Category 4, the mirror contact feedback (Mirror In/ Mirror Out) must be monitored by a Preventa XPS module (or equivalent) that performs external diagnostic monitoring of the SILSafety Integrity Level according to standard IEC 61508.* starter’s mirror contact. If the mirror contact does not open on stop, the next restart is prevented for all SIL starters in the SIL group. The safety-related sensor element is wired to a Preventa XPS module (or equivalent). The Preventa XPS module (or equivalent) outputs are wired to the SIL-IN/SIL Common inputs of the SIL interface module.