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SMARTLINE® RM77
1.5 Terms and definitions
DC
D
Firmware
FIT
FMCW
FMEDA
HFT
High demand or
continuous mode
I/O
λ
DD
λ
DU
λ
SD
λ
SU
Low demand mode
MTBF
MTTF
MTTR
PFD
AVG
PFH
Process safety time
SFF
SIL
SIS
TBF
Type A system
Type B system
T[Proof]
T[Repair]
T[Test]
1oo1
1oo1D
34-VF-25-105 iss.1 GLO April 15 US
Diagnostic Coverage of dangerous failures
Software embedded in the device.
-9
Failure In Time (1×10
failures per hour)
Frequency-Modulated Continuous-Wave. The measuring principle. For more
data, refer to "Technical Data" in the handbook (document [N1]).
Failure Modes, Effects and Diagnostics Analysis
Hardware Fault Tolerance
Where the frequency of demands for operation made on a safety-related system
is greater than one time per year
Input / output
Rate for dangerous detected failure
Rate for dangerous undetected failure
Rate for safe detected failure
Rate for safe undetected failure
Where the frequency of demands for operation made on a safety-related system
is no greater than one time per year
Mean Time Between Failures
Mean Time To Failure
Mean Time To Recovery
Average Probability of Failure on Demand
Probability of a dangerous Failure per Hour
The time interval between a potentially dangerous failure and an error value
from the current output.
Safe Failure Fraction
Safety Integrity Level
Safety Instrumented System
Tank bottom following. A device measurement mode. For more data, refer to
"Technical Data" in the handbook (document [N1]).
"Non-complex" system (all failure modes are well defined). For more data, refer
to subsection 7.4.3.1.2 of IEC 61508-2.
"Complex" system (all failure modes are not well defined). For more data, refer
to subsection 7.4.3.1.2 of IEC 61508-2.
Proof Test Interval
Time to Repair
Internal Diagnostics Test Interval
1 out of 1 channel architecture (single architecture performs the safety function)
1 out of 1 channel architecture with diagnostics
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INTRODUCTION
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