SIL Safety Manual
SM-025-GVO Rev. 0
November 2017
5
Section 2: Acronyms
Acronyms
Section 2: Acronyms
FMEDA:
Failure Modes, Effects and Diagnostic Analysis
HFT:
Hardware Fault Tolerance
(ref: 7.4.4 of IEC 61508-2:2010)
PFD
AVG
:
Average Probability of dangerous Failure on Demand
(ref: 3.6.18 of IEC 61508-4:2010)
SFF:
Safe Failure Fraction, property of a safety related element that is defined by
the ratio of the average failure rates of safe plus dangerous detected failures
and safe plus dangerous failures (ref: 3.6.15 of IEC 61508-4:2010)
SIF:
Safety Instrumented Function, safety function with a specified safety
integrity level which is necessary to achieve functional safety and which
can be either a safety instrumented protection function or a safety
instrumented control function.
SIL:
Safety Integrity Level, discrete level (one out of a possible four) for specifying
the safety integrity requirements of the safety functions to be
allocated to the E/E/PE safety related systems where Safety Integrity Level
4 has the highest level of safety integrity and Safety Integrity Level 1 has the
lowest. (ref: 3.5.8 of IEC 61508-4:2010)
SIS:
Safety Instrumented System – Implementation of one or more Safety
Instrumented Functions. A SIS is composed of any combination of sensor(s),
logic solver(s), and final element(s).
