96 Rockwell Automation Publication 1756-RM012B-EN-P - April 2018
Appendix E GuardLogix Systems Safety Data
Product Failure Rates
The data in the following tables applies to mission times up to and including
20 years.
Table 12 - Safety Parameters
Table 13 - Safety Calculations
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.
Attribute
GuardLogix 5580
Controllers and
Safety Partner
(2)
(3)
GuardLogix 5580
Controller
(2)
(3)
Compact
GuardLogix 5380
Controller
(3)
Safety Function Architecture (HFT)
(1)
100
No Part/ No Effect Detected Failure Rate (λ
NPED
) [hr] 2.80E-06 2.58E-06 4.04E-06
Safe Failure Rate (λ
S
) [failures/hr] 7.24E-07 6.61E-07 7.33E-07
Dangerous Failure Rate (λ
D
) [failures/hr] 7.10E-07 6.61E-07 7.33E-07
Dangerous Detected Failure Rate (λ
DD
) [failures/hr] 7.10E-07 6.54E-07 7.26E-07
Dangerous Undetected Failure Rate (λ
DU
) [failures/hr] 7.38E-11 6.40E-09 7.23E-09
Automatic Diagnostic Test Interval (T
D
) [hr] — <SRT <SRT
Useful Life [yr] 20 20 20
Systematic Capability (SC) 3 3 3
(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
1
756-TD001 and 1756-IN048.
Attribute
GuardLogix 5580
Controllers and Safety
Partner
GuardLogix 5580
Controller
Compact GuardLogix
5380 Controller
PFD
ave
(Mission Time 20 yr) 6.46E-06 5.61E-04 6.33E-04
PFH 7.38E-11 6.40E-09 7.23E-09
STR 4.23E-06 3.90E-06 5.50E-06
MTTF
d
[yr] 160.82 172.74 155.66
PFD =
ave
(λ + λ )t
DU DD CE
t =
CE
λ
DU
λ
D
(
T
1
2
+ MRT
)
λ
DD
λ
D
+MTTR
PFH = λ
DU
STR = λ
S
λ
DD
λ
NPED
++