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Bosch Rexroth AG
Technical Data
Abbreviations
Selection of Performance Level
(PL) and Safety Categories ac‐
cording to EN ISO 13849-1
PL (Performance Level)
c
d
e
Tab.4-23:
EN ISO 13849-1, Performance Level (PL)
Abbreviation
Term
B
-
10d
MTTF
Mean Time to Dangerous Fai‐
d
lure
Diagnostic Coverage
DC
2)
PL
Performance Level
PFH
Probability of Failure per Hour
SIL
Safety Integrated Level
Tab.4-24:
Abbreviations
The Machinery Directive (MD) demands that a fault in control circuit logic, or
an interference or damage thereto, must not lead to a hazardous situation.
This general approach is substantiated in EN ISO 13849-1 "Safety of machi‐
nery - safety related parts of control systems", which defines Performance
Levels (PL a to e) for control parts that are relevant to safety. The PL de‐
pends on the safety category, the MTTF
of diagnosis (DC
) of the corresponding safety circuit.
avg
As in the preceding standard EN 954-1, the safety category describes the
structure of the safety function. The Performance Level (PL), which describes
the conditional probability of failure and the defect discernability of the safety
function, has been added.
The manufacturer of a machine has to select the PL depending on the real
risk potential. The risk potential will be determined from a risk and hazard
analysis. In case of hazards that can cause irreversible injury or death usually
a Performance Level not less than PL "d" is required. The category of the
Performance Level determines if
●
the system has been built in 1-circuit technology, which means that a
failure will lead to a loss of safety, although the availability of compo‐
nents and parts is high (category 1)
●
the system has been built in 1-circuit technology, which means that a
failure will lead to a loss of safety, but the failure will be detected by the
system and will be displayed somehow or other (category 2)
●
the system has been built in 2-circuit technology and that a fault will not
lead to loss of safety (category 3)
DC also means direct current.
2)
DOK-SUPPL*-VEH*30.2***-PR03-EN-P
Rexroth IndraControl VEH 30.2 Hand-Held Terminal
Average probability of a dangerous breakdown
per hour 1/h
≥10
to < 3 x 10
-6
-6
≥10
-7
to < 10
-6
≥10
to < 10
-8
-7
Explanation
Number of cycles until 10% of
the components fail dangerously
(per channel)
Meant time to dangerous failure
(per channel)
Diagnostic of failures
Ability of safety-related parts to
perform a safety function under
predictable conditions to meet
the expected risk reduction
Probability of failure per hour
Safety integrated level
value and the degree of coverage
d
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