Acronyms - ABB LLT100 Functional Safety Manual

Term Meaning
Safety Freedom from unacceptable risk of harm.
Safety Function A specified function that is performed by a safety-related system with the goal, under
consideration of a defined hazardous incident, of achieving or maintaining a safe condition for
the plant.
Safety related system A safety related system performs the safety functions that are required to achieve or maintain a
safe condition.
Ullage The distance by which a container falls short of being full.

Acronyms

Acronym Definition
DC Diagnostic Coverage
DCS Distributed Control System. Control system used in industrial applications to monitor and
control decentralized units.
DTM Device Type Manager. A DTM is a software module that supports specific functions for accessing
device parameters, the setup and the operation of devices, and diagnostics. The DTM is not
executable software. It requires a FDT container program to be activated.
DUT Device Under Test
EDD Electronic Device Description
EUC Equipment Under Control
FDT Field Device Tool
FMEDA Failure Modes, Effects and Diagnostic Analysis
hArT highway Addressable remote Transducer
hFT hardware Fault Tolerance. Ability of a functional unit (hardware) to continue to perform a
required function when faults or errors are prevailing.
hMI human Machine Interface. In this case, the hMI is a combined module consisting of an LCD
display with 4 buttons keypad.
LrV Lower range Value. Device Configuration, LrV of the measurement range
MTBF Mean Time Between Failures
MTTr Mean Time To restoration. Mean time between the occurrence of an error in a unit or in a system
and its repair.
pFD probability of Failure on Demand
pFD Average probability of Failure on Demand
AVG
SFF Safe Failure Fraction. proportion of non-hazardous failures; in other words, the proportion of
failures without the potential to put the safety-related system in a hazardous or impermissible
state.
SIF Safety Instrumented Function. A set of equipment intended to reduce the risk due to a specific
hazard.
SIL Safety Integrity Level. The international standard IEC 61508 defines four discrete Safety Integrity
Levels (SIL 1 to SIL 4). Each level corresponds to a range of probability for the failure of a safety
function. The higher the Safety Integrity Level of the safety-related systems, the lower the
probability that they will not perform the required safety function.
UrV Upper range Value. Device Configuration, UrV of the measurement range.
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User Guide