Safety data
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 STO channels
are not used.
T
M
(a)
CCFHFTSCCat.
DC
(%)
MTTF
D
(a)
PFD
avg
(T
1
= 5
a)
PFD
avg
(T
1
= 2
a)
PFH
(T
1
=
20 a)
(1/h)
SFF
(%)
PL
SIL/
SILCL
Frame
size
2080133≥902569
1.67E-
04
6.68E-
05
8.00E-
09
>90e3R0
2080133≥902568
1.67E-
04
6.68E-
05
8.00E-
09
>90e3R1
2080133≥902568
1.67E-
04
6.68E-
05
8.00E-
09
>90e3R2
2080133≥902935
5.54E-
05
2.23E-
05
2.54E-
09
>99e3R3
2080133≥902932
5.55E-
05
2.23E-
05
2.54E-
09
>99e3R4
2080133≥902934
5.54E-
05
2.23E-
05
2.54E-
09
>99e3R5
2080133≥909380
8.58E-
05
3.44E-
05
3.92E-
09
>99e3R6
2080133≥909380
8.58E-
05
3.44E-
05
3.92E-
09
>99e3R7
2080133≥908792
8.84E-
05
3.69E-
05
4.22E-
09
>99e3R8
3AXD10000320081 D, 3AXD10000015777 J
• The following temperature profile is used in safety value calculations:
•
670 on/off cycles per year with ΔT = 71.66 °C
•
1340 on/off cycles per year with ΔT = 61.66 °C
•
30 on/off cycles per year with ΔT = 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.
• Relevant failure modes:
• The STO trips spuriously (safe failure)
• The STO does not activate when requested
• A fault exclusion on the failure mode “short circuit on printed circuit board” has been
made (EN 13849-2, table D.5). The analysis is based on an assumption that one
failure occurs at one time. No accumulated failures have been analyzed.
• STO response times:
• STO reaction time (shortest detectable break): 1 ms
• STO response time:
- Frames R0…R2: 5 ms (typical), 10 ms (maximum)
160 The Safe torque off function