Competence; Fault Tracing; Safety Data (Sil, Pl) - ABB ACS580-07 Hardware Manual

232 Safe torque off function
￭

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 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.
Frame SIL/ PL
SILCL
R6, R7 3 e
R8, R9 3 e
R10, 3 e
R11
* according to Table E.1 in EN/ISO 13849-1
• This temperature profile is used in safety value calculations:
• 670 on/off cycles per year with Δ T = 71.66 °C
• 1340 on/off cycles per year with Δ T = 61.66 °C
• 30 on/off cycles per year with Δ T = 10.0 °C
• 32 °C board temperature at 2.0% of time
• 60 °C board temperature at 1.5% of time
• 85 °C board temperature at 2.3% of time.
• The safety data is calculated for redundant use, and does not apply if both channels
are not used.
• The STO is a type A safety component as defined in IEC 61508-2.
• Relevant failure modes:
• The STO trips spuriously (safe failure)
• The STO does not activate when requested
SFF PFH PFD
avg
(%) (1/h) (T1 =
2 a)
>99 1.01E- 9.26E-
09 06
>99 1.18E- 1.08E-
09 05
99.88 1.05E- 1.61E-
09 06
PFD MTTF DC*
avg D
(T1 = (a) (%)
5 a)
2.25E- 10867 ≥90
05
2.40E- 2489 ≥90
05
3.94E- 12779 ≥90
06
3AXD10000015777 Rev G, 3AXD10000410558 Rev C
Cat. HFT CCF
(%)
3 1 80
3 1 80
3 1 80
Life-
time
(a)
20
20
20