ABB ACS880-01 Series, Hardware Manual, Page: 206 / 224

206 Safe Torque off function
Maintenance
After the operation of the circuit is verified at start-up, it does not need any
maintenance. However, it is a good practice to check the operation of the function
when the 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, follow the test given in section
Start-up including acceptance test , page 203 .
Fault tracing
The indications given during the normal operation of the Safe torque off function are
selected by drive 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.
Safety data (SIL, PL)
The safety data for the Safe torque off function is given below.
Note : The safety data is calculated for redundant use, and does not apply if both
channels are not used.
Frame IEC 61508
SIL PFH
d
(1/h)
HFT SFF
(%)
T1
(Years)
PFD
U
N
= 208…500 V
R1 3 2.33E-09 (2.33 FIT) 1 99.81 20 4.58E-7
R2 3 2.33E-09 (2.33 FIT) 1 99.81 20 4.58E-7
R3 3 2.33E-09 (2.33 FIT) 1 99.81 20 3.69E-7
R4 3 2.43E-09 (2.43 FIT) 1 99.80 20 5.85E-7
R5 3 2.43E-09 (2.43 FIT) 1 99.80 20 5.85E-7
R6 3 2.44E-09 (2.44 FIT) 1 99.79 20 8.70E-7
R7 3 2.44E-09 (2.44 FIT) 1 99.79 20 8.70E-7
R8 3 3.84E-09 (3.84 FIT) 1 97.03 20 1.56E-4
ACS880-01 HW.book Page 206 Monday, July 1, 2013 4:51 PM