ControlLogix 5590 Safety Data

The following examples show probability of a dangerous failure on demand (PFD) and average frequency of a dangerous failure per hour (PFH) values for a
ControlLogix®
 5590 1oo1 SIL 2 safety system:
The following examples show probability of a dangerous failure on demand (PFD) and average frequency of a dangerous failure per hour (PFH) values for a
ControlLogix®
 5590 1oo1 SIL 2 safety system or 1oo2 SIL 3 safety system:
  • 1oo1 is a single-channel system.
  • 1oo2 is a dual-channel system.

Useful Life

The useful life of
ControlLogix®
 5590 controllers is 20 years.

Safety Data

For safety I/O devices safety data, including PFD and PFH values, see the manuals for those products, as listed in the Additional Resources.

Product Failure Rates

The data in the following tables applies to mission times up to and including 20 years. Mission time (MT) is the length of time over which the device maintains the stated PFD, PFH, and λ ratings before replacement is required.
A detected failure is a failure that is identified by diagnostic tests, proof tests, operator intervention, or normal operation.
Safety Parameters
Attribute
ControlLogix®
 5590 Safety-enabled Controller
ControlLogix®
 5590 Safety-enabled Controller and Safety Partner
Hardware Fault Tolerance (HFT)
The hardware fault tolerance equals
n
, where
n
+1 faults could cause the loss of the safety function. An HFT of 1 means that 2 faults are required before safety is lost.
0
1
No Part/ No Effect Detected Failure Rate (λ
NPED
) [hr]
3.59E-06
6.26E-06
Safe Failure Rate (λ
S
) [failures/hr]
7.33E-07
1.47E-06
Dangerous Failure Rate (λ
D
) [failures/hr]
7.34E-07
1.47E-06
Dangerous Detected Failure Rate (λ
DD
) [failures/hr]
7.26E-07
1.45E-06
Dangerous Undetected Failure Rate (λ
DU
) [failures/hr]
7.67E-09
1.53E-08
Automatic Diagnostic Test Interval (λ
D
) [hr]
< Safety Reaction Time (SRT)
< Safety Reaction Time (SRT)
Useful Life [yr]
20
20
Systematic Capability (SC)
Systematic capability is defined in IEC 61508-4 as the confidence that the systematic safety integrity meets the requirements of the specified SIL rating.
3
3
NOTE:
  • ControlLogix®
     5590 safety-enabled controller values are product failure rates to be used when the product is represented as a block in a reliability block diagram (RBD).
  • ControlLogix®
     5590 safety-enabled controller failure rates are valid for ambient temperatures up to 70 °C (158 °F) and altitudes of up to 2000 m (6561.7 ft). See publications 1756-TD001 and 1756-IN900.
  • The HFT value in the preceding table is the product internal HFT.
Safety Calculations
Attribute
ControlLogix®
 5590 Safety-enabled Controller
ControlLogix®
 5590 Safety-enabled Controllers and Safety Partner
PFD
ave
 (Mission Time 20 yr)
6.72E-04
1.40E-05
PFH
7.67E-09
1.63E-10
STR
5.04E-06
9.18E-06
MTTF
d
 [yr]
155.60
77.80
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).
  • Within the specified useful life (20 years), no proof test is needed.
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