Siemens 6DR50 Series Operating Instructions Manual page 281

Abbreviation Full term in English
SIL Safety Integrity Level
SIS Safety Instrumented System
SIPART PS2 with and without HART
Operating Instructions, 09/2014, A5E00074631-12
Meaning
The international standard IEC 61508 defines four discrete
Safety Integrity Levels (SIL 1 to SIL 4). Each level corresponds
to a range of probability for failure of a safety function. The
higher the Safety Integrity Level of the safety-instrumented
system, the lower the probability that it will not execute the
required safety functions.
A safety-instrumented system (SIS) executes the safety func-
tions that are required to achieve or maintain a safe status in a
system. It consists of sensors, logic unit/control system and final
controlling elements.
Abbreviations
279