6 safety manual – JUMO 14597 safetyM STB/STW Ex - Safety Temperature Limiter and Safety Temperature Monitor Operating Manual User Manual
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Safety function
A function that is performed by an E/E/PE safety-related system, safety-related system
based on other technology, or external equipment for reducing risk with the goal of
achieving or maintaining a safe state for the EUC taking into consideration a specified
dangerous event
Safety integrity
The probability that a safety-related system will perform the required safety function
under all specified conditions within a specified period of time according to
requirements.
Safety Integrity Level (SIL)
One of four discrete levels for specifying the requirement for safety integrity of the
safety functions assigned to the E/E/PE safety-related system. Safety Integrity Level 4
represents the highest level of safety integrity, while Safety Integrity Level 1 represents
the lowest.
Safety-related system
A system that
- performs necessary safety functions that are required to reach or maintain a safe state
for the EUC and
- is designed by itself or with other E/E/PE safety-related systems, safety-related
systems based on other technology, or external equipment for risk reduction to achieve
the necessary safety integrity for the required safety functions.
Safety Instrumented System (SIS)
Safety instrumented system to perform one or more safety-related functions. An SIS
consists of sensor(s), logic system, and actuator(s).
Lambda:
λ
Failure rate per hour
Lambda dangerous:
λ
D
Rate of dangerous failures per hour
Lambda
Δ
angerous
Δ
etect:
λ
DD
Rate of detected dangerous failures per hour
Lambda
Δ
angerous
Υ
ndetect:
λ
DU
Rate of undetected dangerous failures per hour
Lambda:
λ
S
Rate of safe failures per hour
Table 3: Terms and abbreviations according to DIN EN 61508 and DIN EN 61511
Name
Description