Field Of Application; Acronyms And Abbreviations - ABB TTH300 Safety Instructions

Field of Application

1 Field of Application
Temperature monitoring of solids, fluids and gases of all types in containers and pipes
according to the special safety engineering requirements of IEC 61508.
The operating limits are defined in the data sheets and operating instructions for the separate
models. In case of questions, please contact your ABB partner.
2

Acronyms and abbreviations

Acronym /
Abbrevia-
tion
HFT
MTBF
MTTR
PFD
PFD
λ
D
λ
DD
λ
DU
λ
SD
λ
SU
4
English
Hardware Fault
Tolerance
Mean Time
Between Failures
Mean Time To
Repair
Probability of
Failure on Demand
Average Probability
AVG
of Failure on
Demand
Dangerous
Dangerous
Detected
Dangerous
Undetected
Safe Detected
Safe Undetected
TTH200, TTR200, TTH300, TTF300, TTF350
Description
Hardware error tolerance of the unit.
Ability of a functional unit (hardware) to continue to
perform a required function when faults or errors are
prevailing.
Mean Time Between Failures
Mean time between the occurrence of an error in a unit
or system and its repair.
Probability of hazardous failures for a safety function on
demand
Average probability of hazardous failures for a safety
function on demand
Rate of hazardous failures (per hour) affecting a channel
of a subsystem, corresponds to 0.5 λ (assuming 50%
hazardous failures and 50% non-hazardous failures)
Rate of detected hazardous failures (per hour) affecting
a channel of a subsystem. (This is the total rate of
hazardous failures within one channel of a subsystem.)
Rate of undetected hazardous failures (per hour)
affecting a channel of a subsystem. (This is the total rate
of undetected hazardous failures within a subsystem.)
Rate of detected non-hazardous failures (per hour)
affecting a channel of a subsystem. (This is the total rate
of detected non-hazardous failures within one channel of
a subsystem.)
Rate of undetected non-hazardous failures (per hour)
affecting a channel of a subsystem. (This is the total rate
of undetected non-hazardous failures within one channel
of a subsystem.)
SM/TTX200/TTX300/SIL-EN