The person responsible for the design of the complete safety system should also note the
Recommendation of Use CNB/M/11.050 published by the European co-ordination of Notified
Bodies for Machinery concerning dual-channel safety-related systems with electromechanical
outputs:
• When the safety integrity requirement for the safety function is SIL 3 or PL e (cat. 3 or
4), the proof test for the function must be done at least every month.
• When the safety integrity requirement for the safety function is SIL 2 (HFT = 1) or PL d
(cat. 3), the proof test for the function must be done at least every 12 months.
This is a recommendation and depends on the required (not achieved) SIL/PL. For example,
contactors, breakers, safety relays, contactor relays, emergency stop buttons, switches,
etc. are typically safety devices which have electromechanical outputs. The STO circuit of
the drive does not have electromechanical outputs. Also, the FSO and FSE-31 modules do
not have electromechanical outputs.
Competence
The person who does the maintenance and proof test activities of the safety function must
be a competent person with expertise and knowledge of the safety function and functional
safety, as required by IEC 61508-1 clause 6.
Residual risk
The safety functions are used to reduce the recognized hazardous conditions. In spite of
this, it is not always possible to eliminate all potential hazards. Thus, the warnings for the
residual risks must be given to the operators.
Intentional misuse
The safety circuit is not designed to protect a machine against intentional misuse.
Decommissioning
When you decommission a drive, make sure that the functional safety of the machine is
maintained by other means until the decommissioning is completed.
60 Maintenance
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