WIKA S-20 - Manual (Page 5)

5
GB
WIKA Safety manual pressure transmitter, model S-20
14082128.02 06/2014 GB/D/F/E
1.4 Abbreviations
Abbreviation Description
FMEA Failure Modes Effects and Diagnostic Analysis
MTTFd Expected value of the mean time to dangerous failure
PL Performance level: Discrete level which specifies the ability of safety-related parts of control systems to perform a
safety function under foreseeable conditions.
TM Service life
Settling time Time period between the step change in the pressure signal and the time at which the output signal deviates by no
more than 1 % tolerance from the value of the final stable condition.
Switch-on time Time after power-on until the first valid measured value (max. ±1% FSO error) is present at the signal output.
Table 1-2: Abbreviations (see also EN ISO 13849-1:2008 and EN ISO 13849-2:2012)
1. General information