Competence; Residual Risk; Intentional Misuse; Decommissioning - ABB ACS880-07 User Manual

52 Maintenance
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 an emergency stop circuit or a drive, make sure that the functional
safety of the machine is maintained by other means until the decommissioning is completed.