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Appendix E
GuardLogix Systems Safety Data
Product Failure Rates
96
The data in the following tables applies to mission times up to and including
20 years.
Table 12 - Safety Parameters
Attribute
(1)
Safety Function Architecture (HFT)
No Part/ No Effect Detected Failure Rate (λ
Safe Failure Rate (λ
) [failures/hr]
S
Dangerous Failure Rate (λ
) [failures/hr]
D
Dangerous Detected Failure Rate (λ
) [failures/hr]
DD
Dangerous Undetected Failure Rate (λ
DU
Automatic Diagnostic Test Interval (T
) [hr]
D
Useful Life [yr]
Systematic Capability (SC)
(1) The HFT specified here is the product internal HFT.
(2) These values are product failure rates to be used when the product is represented as a block in a reliability block diagram (RBD).
(3) These product failure rates are valid for ambient temperatures up to 60 °C (140 °F) and altitudes of up to 2000 m (6561.7 ft). See publication
1756-TD001
and 1756-IN048.
Table 13 - Safety Calculations
Attribute
PFD
(Mission Time 20 yr)
ave
PFH
STR
MTTF
[yr]
d
Assumptions for safety calculations:
• Component failure rates are constant over the life of the product.
• All detected failures (safe and dangerous) result in the safe state
(MRT=0).
• Example mission time of 10 or 20 years. Within the specified useful life
(20 years), no proof test is needed.
PFD =
(λ + λ )t
ave
DU
DD CE
λ
T
(
DU
1
t =
+ MRT
CE
λ
2
D
PFH = λ
DU
Rockwell Automation Publication 1756-RM012B-EN-P - April 2018
GuardLogix 5580
Controllers and
(2) (3)
Safety Partner
1
) [hr]
2.80E-06
NPED
7.24E-07
7.10E-07
7.10E-07
) [failures/hr]
7.38E-11
—
20
3
GuardLogix 5580
Controllers and Safety
GuardLogix 5580
Partner
Controller
6.46E-06
5.61E-04
7.38E-11
6.40E-09
4.23E-06
3.90E-06
160.82
172.74
STR = λ
λ
)
DD
+
MTTR
λ
D
MTTF = λ
Compact
GuardLogix 5580
GuardLogix 5380
(2) (3)
(3)
Controller
Controller
0
0
2.58E-06
4.04E-06
6.61E-07
7.33E-07
6.61E-07
7.33E-07
6.54E-07
7.26E-07
6.40E-09
7.23E-09
<SRT
<SRT
20
20
3
3
Compact GuardLogix
5380 Controller
6.33E-04
7.23E-09
5.50E-06
155.66
+
λ
+
λ
S
DD
NPED
1
D
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