ABB ACS880-04FXT, Hardware Manual

Page: 178 / 196

Maintenance
After the operation of the circuit is validated at start-up, the STO function shall be maintained
by periodic proof testing. In high demand mode of operation, the maximum proof test interval
is 20 years. In low demand mode of operation, the maximum proof test interval is 5 or 2
years; see section
Safety data (page 180) . It is assumed that all dangerous failures of the
STO circuit are detected by the proof test. To perform the proof test, do the Acceptance test
procedure (page 175) .
Note: See also the Recommendation of Use CNB/M/11.050 (published by the European
co-ordination of Notified Bodies) 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 performed 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 performed at least every 12 months.
The STO function of the drive does not contain any electromechanical components.
In addition to proof testing, it is a good practice to check the operation of the function when
other maintenance procedures are carried out on the machinery.
Include the Safe torque off operation test described above in the routine maintenance
program of the machinery that the drive runs.
If any wiring or component change is needed after start up, or the parameters are restored,
do the test given in section
Acceptance test procedure (page 175) .
Use only spare parts approved by ABB.
Record all maintenance and proof test activities in the machine logbook.
￭ 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.
178 The Safe torque off function