77
item Controller BL 1-04 /C
― Product manual
11.4 Safety technology glossary
Term/abbreviation
Description
CCF
Common cause failure in accordance with EN ISO 13849-1
DC avg
Average diagnostic coverage in accordance with IEC 61508 and EN 61800-5-2.
HFT
Hardware fault tolerance in accordance with IEC 61508.
Cat.
Safety category in accordance with EN ISO 13849-1, level 1- 4.
iMS
®
item MotionSoft
®
, software for configuration and start-up.
MTTFd
Mean time to dangerous failure. Time in years until the first dangerous failure will have
occurred with 100% probability, in accordance with EN ISO 13849-1.
Emergency off
In accordance with EN 60204-5-1 Electrical safety is ensured in case of an emergency by
switching off the electrical energy supply to the entire installation or part of it. An emergen
-
cy off is to be used where a risk of electric shock or other electrical risk exists.
Emergency stop
In accordance with EN 60204-5-1 In an emergency, functional safety is ensured by stopp
-
ing a machine or moving parts.
An emergency stop is used to stop a process or a movement which has become hazardous.
OSSD
Output signal switching device, output signals with 24 V level cycle rates for error detection.
PFD
Probability of failure on demand in accordance with IEC 61508.
PFH
Probability of dangerous failures per hour in accordance with IEC 61508.
PL
Performance level in accordance with EN ISO 13849-1: Levels a to e
PWM
Pulse width modulation. Stands for the digital actuation of the power semiconductors with a
variable duty cycle in order to adjust a voltage at the motor output.
SFF
Safe failure fraction [%], ratio between the failure rates of safe and dangerous (but recogni
-
sable) failures and the total number failures in accordance with IEC 61508.
Safety relay
Device for executing safety functions or for establishing a safe state of the machine by
switching off the energy supply for dangerous machine functions. The desired safety function
can be achieved only in combination with other risk reduction measures, e.g. by switching off a
servo drive.
SIL
Safety integrity level. Discrete levels for defining the requirements for the safety integrity of
safety functions in accordance with IEC 61508, EN 62061 and EN ISO 13849.
SIL CL
Maximum SIL that can be required from a sub-system.
SS1
Safe stop 1 in accordance with EN 61800-5-2.
STO
Safe torque off in accordance with EN 61800-5-2.
T
Duration of use in accordance with EN ISO 13849-1.
