Terms and abbreviations
Description
Term
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. (EN ISO 13849-1)
Cat.
Common cause failure (%) (EN ISO 13849-1)
CCF
Frame size designation of the diode supply module
D8T
Diagnostic coverage (EN ISO 13849-1)
DC
Failure in time: 1E-9 hours (IEC 61508)
FIT
Physical size of the drive or power module
Frame, frame size
Hardware fault tolerance (IEC 61508)
HFT
Insulated gate bipolar transistor
IGBT
Average probability of dangerous failure on demand (IEC 61508)
PFD
avg
Average frequency of dangerous failures per hour (IEC 61508)
PFH
Performance level. Levels a...e correspond to SIL (EN ISO 13849-1)
PL
Prevention of unexpected start-up
POUS
Systematic capability (IEC 61508)
SC
Safety integrity level (1...3) (IEC 61508)
SIL
Maximum SIL (level 1...3) that can be claimed for a safety function or subsystem
(IEC/EN 62061)
SILCL
Safe torque off (IEC/EN 61800-5-2)
STO
Proof test interval. Defines the probabilistic failure rate (PFH or PFD) for the safety
function or subsystem. Performing a proof test at a maximum interval of T1 is required
to keep the SIL capability valid. The same interval must be followed to keep the PL
capability (EN ISO 13849) valid. Note that any T1 values given cannot be regarded
as a guarantee or warranty.
T1
14 Introduction to the manual
