Assessment of Functional Safety According to
IEC 61508
The 7UM85 devices have been subjected to an assessment of functional safety according to the standard
IEC 61508.
The following table shows the assessment results of the 8 variants for the 7UM85 device. All the assessment
values are based on an ambient temperature of 40 °C (104 °F) according to the standard IEC 60255-1.
NOTE
If you need assessment values which are based on other ambient temperatures, contact the Customer
Support Center. You can find more information of the Customer Support Center in Support, Page 5.
Item Variant 1 Variant 2 Variant 3 Variant 4 Variant 5 Variant 6 Variant 7 Variant 8
Diagnostic coverage 87 % 85 % 89 % 82 % 82 % 82 % 84 % 86 %
Safe fail fraction (SFF) 94 % 93 % 94 % 91 % 91 % 92 % 92 % 93 %
Undetected, dangerous failure
rate (λ
DU
)
3866 4856 3513 6858 6285 5212 4222 4283
Detected, dangerous failure
rate (λ
DD
)
25 783 27 741 29 336 31 007 29 206 24 492 22 535 25 940
Undetected and detected safe
failure rate (λ
SU
and λ
SD
)
29 883 32 646 30 990 37 836 36 091 31 651 28 888 30 901
Probability of failure on
demand (PFD)
1.7 ⋅ 10
-2
2.1 ⋅ 10
-2
1.6 ⋅ 10
-2
3.0 ⋅ 10
-2
2.7 ⋅ 10
-2
2.3 ⋅ 10
-2
1.9 ⋅ 10
-2
1.9 ⋅ 10
-2
Safety integrity level (SIL) 1
Hardware architecture 1oo1
Hardware failure tolerance 0
Type of subsystem B
Proof test interval 1 year
Mean time to restore 8 h
Base module: CP300_2 + PS201 + IO202
Variant 1: Base module + IO205 + IO206
Variant 2: Base module + IO205 + IO207
Variant 3: Base module + IO231 + IO206
Variant 4: Base module + IO207 + IO207 + IO207
Variant 5: Base module + IO207 + IO207 + IO201
Variant 6: Base module + IO207 + IO207
Variant 7: Base module + IO207 + IO206
Variant 8: Base module + IO201 + IO205
5
SIPROTEC 5, Additional Information on the Protection of Explosion-Proof Motors with Type of Protection Increased Safety e,
Manual
31
C53000-H5050-C078-1, Edition 03.2019
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