Safety Function - Siemens SIRIUS 3SK1 Equipment Manual

Safety systems - General information

4.2 Safety function

4.2 Safety function
A safety function describes the reaction of a machine/plant to the occurrence of a specific event
(e.g. opening of a protective door). Execution of the safety function(s) is carried out by a safety-
related control system. This usually comprises three subsystems, detecting, evaluating and
reacting.
Detecting (sensors):
• Detecting a safety requirement,
e. g.: EMERGENCY STOP or a sensor for monitoring a hazardous area (light array, laser
scanner, etc.) is operated.
Evaluating (safety relay):
• Detecting a safety requirement and safely initiating the reaction (e.g. switching off the safety-
related outputs).
• Monitoring the correct operation of sensors and actuators.
• Initiating a reaction upon detection of faults.
The 3SK1 products described in this manual are evaluation units for safety functions.
Reacting (actuators):
• Switching off the hazard by means of downstream actuators.
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SIRIUS 3SK1 Safety Relays and 3RQ1 Positively-Driven Coupling Relays
Equipment Manual, 05/2021, A5E02526190021A/RS-AE/005