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15 Terms and abbreviations
Blanking
Optional function ensuring that objects
are in the protected area which are
larger than the detection capacity
without the OSSDs switching off�
ESPE
Electro-Sensitive Protective
Equipment
CCF
Common Cause Failure
DC
avg
Average Diagnostic Coverage
Muting
Temporary bridging of a safety function
by safety-related parts of the control
system�
MTTF
d
Mean Time To Dangerous
Failure
OSSD
Output Signal Switch Device
Output signal switch element,
static safety-related output�
PFH
(PFH
D
)
Probability of (dangerous)
Failure per Hour
PL
Performance Level
Capability of safety-related parts to
perform a safety function at predictable
conditions to fulfil the expected risk
reduction�
SIL
Safety integrity level
SIL 1-4 to IEC 61508� The higher the
SIL the lower the probability that a
safety function will fail�
SIL
cl
Safety integrity level
claim limit
(to IEC 62061)
T
M
Mission Time
Technical data and further information at www�ifm�com
