Instruction Manual Supplement
D104215X012
DLC3100 SIS Digital Level Controller
April 2018
3
3. Terms, Abbreviations, and Acronyms
249 Fisher caged and cageless displacer level sensors.
Device Response
TIme
Time required for the digital level controller to carry out its part of the safety function,
includes time taken to sense a change in input (lever assembly) and transmit a
corresponding output signal.
Diagnostic test
interval
Time taken to detect internal faults.
DLC3100 SIS
Digital level controller, product model designation for Safety Instrumented System
applications.
Fault Reaction Time Time taken to respond once a fault is detected.
FIT Failure In Time (1x10
-9
failures per hour)
FMEDA Failure Mode Effect and Diagnostic Analysis
HART
Highway Addressable Remote Transducer, open protocol for digital communication
superimposed over a direct current.
HFT Hardware Fault Tolerance
λ
Failure rate. λ
DD
: dangerous detected; λ
DU
: dangerous undetected; λ
SD
: safe detected;
λ
SU
: safe undetected.
Low Demand Mode
Mode of operation of a safety instrumented function where the demands to activate the SIF
are less than once every two proof test intervals.
PFD
AVG
Average Probability of Failure on Demand
Process Safety Time
Period of time between a failure occurring in the system (with the potential to give rise to a
hazardous event) and the occurrence of the hazardous event if the safety function is not
performed
Safety Freedom from unacceptable risk of harm.
Safety Function
Function of a device or combination of devices intended to be used within a Safety
Instrumented System to reduce the probability of a specific hazardous event to an
acceptable level.
SFF Safe Failure Fraction
SIF Safety Instrumented Function
SIL Safety Integrity Level
SIS Safety Instrumented System
Type B Element
“Complex” element (using complex components such as micro controllers or
programmable logic); for details see 7.4.4.1.3 of IEC 61508-2.
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