ABB ACS800-104

Introduction to the manual 9
Abbreviations
Abbreviations used in this manual are listed below.
Abbr. Reference Description
ASTO Safe torque off board
Cat. EN ISO 13849-1 Category. Classification of the safety-related parts of a control system in
respect of their resistance to faults and their subsequent behavior in the
fault condition, and which is achieved by the structural arrangement of
the parts, fault detection and/or by their reliability. The categories are: B,
1, 2, 3 and 4.
CCF EN ISO 13849-1 Common cause failure (%)
DC EN ISO 13849-1 Diagnostic coverage
HFT IEC 61508 Hardware fault tolerance
MTTF
D
EN ISO 13849-1 Mean time to dangerous failure: (Total number of life units) / (Number of
dangerous, undetected failures) during a particular measurement
interval under stated conditions
PFD
avg
IEC 61508 Average probability of dangerous failure on demand, that is, mean
unavailability of a safety-related system to perform the specified safety
function when a demand occurs
PFH IEC 61508 Average frequency of dangerous failures per hour, that is, average
frequency of a dangerous failure of a safety related system to perform
the specified safety function over a given period of time
PL EN ISO 13849-1 Performance level. Levels a…e correspond to SIL
SC IEC 61508 Systematic capability
SFF IEC 61508 Safe failure fraction (%)
SIL IEC 61508 Safety integrity level (1…3)
SILCL IEC/EN 62061 Maximum SIL (level 1…3) that can be claimed for a safety function or
subsystem
SS1 IEC/EN 61800-5-2 Safe stop 1
STO IEC/EN 61800-5-2 Safe torque off
T
1
IEC 61508 Proof test interval. T
1
is a parameter used to define the probabilistic
failure rate (PFH or PFD) for the safety function or subsystem.
Performing a proof test at a maximum interval of T
1
is required to keep
the SIL capability valid. The same interval must be followed to keep the
PL capability (EN ISO 13849) valid.
See also section Maintenance.
T
M
EN ISO 13849-1 Mission time: the period of time covering the intended use of the safety
function/device. After the mission time elapses, the safety device must
be replaced. Note that any T
M
values given cannot be regarded as a
guarantee or warranty.