Allen-Bradley 1756 Series

130 Rockwell Automation Publication 1756-UM013B-EN-P - October 2019
Appendix D Safety Data for Safety Modules
1756-IB16S Safety Data
Tab le 8 lists the safety data for the 1756-IB16S module.
Table 8 - 1756-IB16S Module Safety Parameter Data
Attribute
Point Operation Type
Single Channel Dual Channel
(at controller instruction
level)
Safety Function Architecture (HFT) 0 1
Safe Failure Rate (λ
s
) [failures/hr] 7.9621E-07 8.6252E-07
Safe Detected Failure Rate (λ
SD
)
(1)
7.95153E-07 8.61767E-07
Safe Undetected Failure Rate (λ
SU
)
(1)
1.05746E-09 7.52962E-10
Dangerous Failure Rate (λ
D
) [failures/hr] 4.49496E-07 5.34022E-07
Dangerous Detected Failure Rate (λ
DD
) [failures/hr] 4.48899E-07 5.33556E-07
Dangerous Undetected Failure Rate (λ
DU
) [failures/hr] 3.80996E-10 4.6619E-10
SRT [millisecond] 6
Automatic Diagnostic Test Interval (TD) [hr] 4
Useful Life [yr] 20
Systematic Capability (SC) 3
Safe Failure Fraction (SFF) [%] 99.97% 99.97%
PFH 3.80996E-10 4.6619E-10
PFD
AVE
10 yrs 1.66876E-05 2.04191E-05
Mission Time™ 20 yrs 3.33753E-05 4.08383E-05
Diagnostic Coverage Average (DC
AVE
) 99.87% 99.91%
Spurious Trip Rate (STR) 5.90E-06 —
MTTF [years] 91.64 81.74
MTTF
D
[years] 253.96 213.76
(1) (λSD) and (λSU) are calculated with assumption of Diagnostic Coverage of Safe Failure is same as Diagnostic Coverage of Dangerous Failure