Possible startup testing applications:
• Seasonally operated machines
• Function test after extensive maintenance/repair work
• Realization of a test routine for safety functions without automatic test (e.g. EMERGENCY
STOP)
3.7.4 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 as per EN 62061, SIL 3 as per IEC 61508 and PL e (Cat. 4) as per 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.
① EMERGENCY STOP
② Safety relay
Series connection of mechanical position switches
In general, position switches may be connected in series if measures ensure that several
protective doors are not regularly opened simultaneously (otherwise a fault cannot be detected).
For safety level SILCL3 in accordance with EN 62061, SIL3 in accordance with IEC 61508, and PL e
(Cat. 4) in accordance with ISO 13849-1, however, they must never be connected in series,
because every hazardous error must be detected (independently of the operating personnel).
Overview
3.7 Safety systems - General information
SIRIUS 3RK3 Modular Safety System
58 Equipment Manual, 07/2020, NEB926253002000/RS-AC/006
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