Terms And Abbreviations - ABB ACS480-04-09A8-1 Hardware Manual

• 85 °C board temperature at 2.3% of time.
• The STO is a type A safety component as defined in IEC 61508-2.
• Relevant failure modes:
• The STO trips spuriously (safe failure)
• The STO does not activate when requested
• A fault exclusion on the failure mode "short circuit on printed circuit board" has been
made (EN 13849-2, table D.5). The analysis is based on an assumption that one
failure occurs at one time. No accumulated failures have been analyzed.
• STO response times:
• STO reaction time (shortest detectable break): 1 ms
• STO response time: 5 ms (typical), 15 ms (maximum)
• Fault detection time: Channels in different states for longer than 200 ms
• Fault reaction time: Fault detection time + 10 ms
• Indication delays:
• STO fault indication (parameter 31.22) delay: < 500 ms
• STO warning indication (parameter 31.22) delay: < 1000 ms
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Terms and abbreviations

Term or ab- Reference
breviation
Cat. EN ISO 13849-1
CCF EN ISO 13849-1
DC EN ISO 13849-1
HFT IEC 61508
MTTF D EN ISO 13849-1
PFD avg IEC 61508
Description
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.
Common cause failure (%)
Diagnostic coverage
Hardware fault tolerance
Mean time to dangerous failure: (Total number of life units)
/ (Number of dangerous, undetected failures) during a partic-
ular measurement interval under stated conditions
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
The Safe torque off function 219