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6
GFK-2734 Chapter 6 Connection examples for the safe relay outputs and the safety-related segment circuit 6-3
6.3 Measures required to achieve a specific safety
integrity level
The safety integrity level (SIL, SIL CL, performance level, and category) that can be
achieved is specified for each connection example.
SIL, SIL CL
In order to determine PFH and PFD depending on the SIL, see "Determining PFH, PFD,
and MTTFd" on page 7-1.
Performance level
Category In order to actually achieve the specified category, the required measures listed below
must be implemented.
Cat. 2
– Use proven safety principles.
– Use appropriately qualified actuators (see Section "Requirements for controlled
devices/actuators" on page 2-5).
– Please note that mechanical failure of the switching device can result in the loss of the
safety function.
– Prevent the welding of contacts with appropriate protection against overcurrent and
surge voltage.
– Please note that a single error can result in the loss of the safety function between
tests.
– Ensure that the external wiring is tested by the machine control system on machine
startup and at suitable intervals. This test must detect the loss of the safety function.
– In the event of an error, either safe disconnection must be implemented or a warning
(optical and/or audible) must be generated depending on the application.
In order to determine the probability of failure according to EN 62061 (SIL CL), use this
standard.
Use standard EN ISO 13849-1 to determine the performance level.