Abbreviations And Symbols - Eaton ZB12 XTOB Series Manual

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0.3 Abbreviations and symbols

0.3 Abbreviations and symbols
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Symbols used in this manual have the following meanings:
Ex e Type of protection "Increased Safety"
FIT Failure In Time
(number of dangerous failures in 10
HFT Hardware-Fault-Tolerance
HM Highest possible setting current
MTTF Mean Time To Dangerous Failure
d
NM Lowest possible setting current
PL Performance Level
PTB Physikalisch-Technische Bundesanstalt
(German Federal Testing Laboratory: Accredited certification authority for devices
operated in Ex e areas)
SIL Safety Integrity Level
ZB12-..., ZB32-... 11/16 MN03407004Z-DE/EN www.eaton.com
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hours)