Siemens SINUMERIK 840D sl Function Manual page 593

05.08
control architectures, were used to derive the average, hazardous probability of
failure per hour.
Redundancy
Availability of more than the necessary equipment to execute the required tasks.
Risk
Combination of the probability of damage occurring and the extent of the damage.
Safety
Free from any unacceptable risk.
Functional safety
The part of the safety of a piece of equipment (e.g. machine, plant) that depends
on the correct function.
Safety function
Function, (e.g. of a machine or a control) whose failure can increase the risk/risks.
Safety functions of controls (EN 954)
A function "initiated by an input signal and processed by the safety–related parts of
controls, that allows the machine (as system) to reach a safe condition".
Safety goal
To keep the potential hazards for personnel and the environment as low as pos-
sible without restricting more than absolutely necessary, industrial production, the
use of machines or the manufacture of chemical products.
Safety Integrity Level (SIL)
Measure, defined in IEC 61508, for the safety–related performance of an electrical
or electronic control device.
Stop Category
Term used in EN 60204–1 to designate three different stopping functions.
Stopping
Function that is intended to avoid or reduce impending or existing hazards for per-
sonnel, damage to the machine or the execution of work. This has priority over all
operating modes.
© Siemens AG 2008 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
Appendix
A.4 Terms
A-593