vi HC900 Process & Safety Controller Safety Manual Revision 1.9
01/14
Terms and Abbreviations
1oo1 One out of one
2oo3 Two out of three
Basic Safety The equipment must be designed and manufactured such that it protects against risk
of damage to persons by electrical shock and other hazards and against resulting fire
and explosion. The protection must be effective under all conditions of the nominal
operation and under single fault condition
DU Dangerous Undetected failures
FMEDA Failure Modes, Effects and Diagnostic Analysis
Functional Safety The ability of a system to carry out the actions necessary to achieve or to maintain a
defined safe state for the equipment / machinery / plant / apparatus under control of
the system
GTS Global Technical Support Center
HFT Hardware Fault Tolerance
Low demand mode Mode, where the frequency of demands for operation made on a safety-related system
is no greater than one per year and no greater than twice the proof test frequency.
PFD
AVG
Average Probability of Failure on Demand
Safety Freedom from unacceptable risk of harm
Safety Assessment The investigation to arrive at a judgment - based on evidence - of the safety achieved
by safety-related systems. Further definitions of terms used for safety techniques and
measures and the description of safety related systems are given in IEC 61508-4.
SFF Safe Failure Fraction, the fraction of the overall failure rate of a device that results in
either a safe fault or a diagnosed unsafe fault.
SIF Safety Instrumented Function, a set of equipment intended to reduce the risk due to a
specific hazard (a safety loop).
SIL Safety Integrity Level, discrete level (one out of a possible four) for specifying the
safety integrity requirements of the safety functions to be allocated to the E/E/PE
safety-related systems where Safety Integrity Level 4 has the highest level of safety
integrity and Safety Integrity Level 1 has the lowest.
SIS Safety Instrumented System – Implementation of one or more Safety Instrumented
Functions. A SIS is composed of any combination of sensor(s), logic solver(s), and
final element(s).
To Next Page
Loading...
