Abbreviations Used in IEC 61511

These are the abbreviations commonly used in Functional Safety and in IEC 61511 standard.

Abbreviation & Full expression

1. λ                  Failure rate, the ratio of the total number of failures occurring in a given period of time
2. λD               failure rate of dangerous failures
3. λDD             f ailure rate of dangerous failures detected by diagnostics
4. λDU              failure rate of dangerous failures undetected by diagnostics
5. λS                 failure rate of safe failures
6. 1oo1             1 out of 1 voting (Simplex)
7. 1oo2             1 out of 2
8. AI                 Analogue Input
9. ANSI             American National Standards Institute
10. AC/DC         Alternating current/direct current
11. AIChE           American Institute of Chemical Engineers
12. ALARP           As low as reasonably practicable
13. ANSI             American National Standards Institute
14. AP                 Application program
15. BPCS             Basic process control system
16. CCPS            Centre for Chemical Process Safety (AIChE)
17. C&E              Cause and Effect
18. CBA              Cost Benefit Analysis
19. CCF              Common Cause Failure
20. COMAH       Control Of Major Accident Hazards
21. DC               Diagnostic coverage
22. DD               Dangerous Detected
23. DU               Dangerous Undetected
24. DI                 Digitial Input
25. DO               Digital Output
26. ESD              Emergency Shutdown
27. F & G           Fire and Gas
28. FC                Fail Closed
29. FDS              Function Design Specification
30. E/E/PE          Electrical/electronic/programmable electronic
31. EMC             Electro-magnetic compatibility
32. FAT               Factory acceptance test
33. FPL               Fixed program language
34. FSA              Functional safety assessment
35. FSMS           Functional safety management system
36. FTA              Fault tree analysis
37. FVL              Full variability language
38. HFT              Hardware fault tolerance
39. H&RA          Hazard & risk assessment
40. HMI             Human Machine Interface
41. IEC               International Electrotechnical Commission
42. ISA               International Society of Automation
43. ISO               International Organization for Standardization
44. LVL               Limited variability language
45. MooN          “M” out of “N” channel architecture
46. MPRT            Maximum permitted repair time
47. MRT              Mean repair time
48. MTTR            Mean time to restoration
49. NFPA             National Fire Protection Association (US)
50. NP                 non-programmable
51. OEM              Original Equipment Manufacturer
52. PE                  Programmable electronics
53. PES                Programmable electronic system
54. PFD               Probability of dangerous failure on demand
55. PFDavg         Average probability of dangerous failure on demand
56. PFH               Probability (average frequency of dangerous failures) of failure per hour
57. pl                   Plural
58. PLC                Programmable logic controller
59. SAT                Site acceptance test
60. SC                  Systematic capability
61. SIF                  Safety instrumented function
62. SIL                  Safety integrity level
63. SIS                  Safety instrumented system
64. SRS                 Safety requirement specification