Competence; Fault Tracing - ABB ACH580-31 Series Hardware Manual

212 The Safe torque off function
If any wiring or component change is needed after start up, or the parameters are
restored, follow the test given in section Acceptance test procedure on page 208.
Use only ABB approved spare parts.
Record all maintenance and proof test activities in the machine logbook.
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Competence

The maintenance and proof test activities of the safety function must be carried out by
a competent person with adequate expertise and knowledge of the safety function as
well as functional safety, as required by IEC 61508-1 clause 6.

Fault tracing

The indications given during the normal operation of the Safe torque off function are
selected by parameter 31.22.
The diagnostics of the Safe torque off function cross-compare the status of the two
STO channels. In case the channels are not in the same state, a fault reaction
function is performed and the drive trips on an "STO hardware failure" fault. An
attempt to use the STO in a non-redundant manner, for example activating only one
channel, will trigger the same reaction.
See the drive firmware manual for the indications generated by the drive, and for
details on directing fault and warning indications to an output on the control unit for
external diagnostics.
Any failures of the Safe torque off function must be reported to ABB.