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. CMC            Consequence Mitigation System
21. COMAH       Control Of Major Accident Hazards
22. DC               Diagnostic coverage
23. DD               Dangerous Detected
24. DU               Dangerous Undetected
25. DI                 Digitial Input
26. DO               Digital Output
27. ESD              Emergency Shutdown
28. F & G           Fire and Gas
29. FC                Fail Closed
30. FDS              Function Design Specification
31. E/E/PE          Electrical/electronic/programmable electronic
32. EMC             Electro-magnetic compatibility
33. FAT               Factory acceptance test
34. FPL               Fixed program language
35. FSA              Functional safety assessment
36. FSMS           Functional safety management system
37. FTA              Fault tree analysis
38. FVL              Full variability language
39. HFT              Hardware fault tolerance
40. H&RA          Hazard & risk assessment
41. HMI             Human Machine Interface
42. IEC               International Electrotechnical Commission
43. ISA               International Society of Automation
44. ISO               International Organization for Standardization
45. LVL               Limited variability language
46. MooN          “M” out of “N” channel architecture
47. MPRT            Maximum permitted repair time
48. MRT              Mean repair time
49. MTTR            Mean time to restoration
50. NFPA             National Fire Protection Association (US)
51. NP                 non-programmable
52. OEM              Original Equipment Manufacturer
53. PE                  Programmable electronics
54. PES                Programmable electronic system
55. PFD               Probability of dangerous failure on demand
56. PFDavg         Average probability of dangerous failure on demand
57. PFH               Probability (average frequency of dangerous failures) of failure per hour
58. pl                   Plural
59. PLC                Programmable logic controller
60. SAT                Site acceptance test
61. SC                  Systematic capability
62. SIF                  Safety instrumented function
63. SIL                  Safety integrity level
64. SIS                  Safety instrumented system
65. SRS                 Safety requirement specification