Series Connection Of Sensors - Siemens SIRIUS 3SK1 Manual

Safety systems - General information
4.3 Basic terminology
4.3.14

Series connection of sensors

Series connection of EMERGENCY STOP command devices
It is possible to connect EMERGENCY STOP command elements in series up to the highest
safety level (SILCL 3 in accordance with IEC 62061, SIL 3 in accordance with IEC 61508
and PL e (Cat. 4) in accordance with ISO 13849-1), because it is assumed that only one
EMERGENCY STOP is operated at a time. This ensures that errors and defects can be
detected.
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Manual, 04/2013, A5E02526190021A/RS-AA/01
3SK1 safety relays