Terms and abbreviations
FIT
Safe switch-off
distance
MTTF
OSSD
PDF
PDF-M
PFD
avg
PFH bzw. PFH
D
Safe state
SIL
SIL
cl
T
T1
Failure in Time
-9
x 10
/h
Assured
release distance
Mean time to failure
Output Signal Switch
Device
Proximity device with
defined behaviour un-
der fault conditions
PDF with self Monito-
ring
Average Probality of
Failure on Demand
Probability of a dange-
rous Failure per Hour
-
Safety Integrity Level
Safety Integrity
Level
claim limit
Life time
Test Interval
(between life testing
of the safety function)
Failure rate (per hour)
-9
x 10
/h
Distance from the active face within which
the correct detection of the absence of
a defined object (see Chapter 8) under all
defined environmental conditions and the
defined safety level can be achieved.
Output signal switching element (for
GM701S: two PNP solid-state outputs)
Average probability of dangerous failures
of a safety function in the case of request
Minimum one of the two OSSD is swit-
ched off
SIL 1-4 to DIN EN 61508.
The higher the SIL the lower the probabil-
ity that a safety function will fail.
= service life
UK
37