Isolating Transducers Im33-**(Ex)-Hi/24Vdc - turck IM35-11Ex-Hi/24VDC Bedienungsanleitung

5.1 Isolating Transducers IM33-**(Ex)-Hi/24VDC

The FMEDA carried out on the Isolating Transducer IM33-22Ex-Hi/24VDC leads under the
assumptions described in sections 4.2.3 and 5 to the following failure rates:
λ = 0,00E-00 1/h
sd
λ = 6,00E-09 1/h
su
λ = 0,00E-00 1/h
dd
λ = 4,39E-08 1/h
du
= 6,71E-08 1/h
λ
high
λ = 2,33E-07 1/h
low
λ = 3,15E-07 1/h
no effect
λ = 6,65E-07 1/h
total
λ = 5,28E-08 1/h
not part
MTBF = MTTF + MTTR = 1 / (λ
These failure rates can be turned over into the following typical failure rates:
Failure category (Failure rates in FIT)
Fail High (detected by the logic solver)
Fail detected (int. diag.) = λ
Fail high (inherently) = λ
Fail Low (detected by the logic solver)
Fail detected (int. diag.) = λ
Fail low (inherently) = λ
Fail Dangerous Undetected
No Effect
Not part
MTBF = MTTF + MTTR
Under the assumptions described in section 4.2.4 and 5 the following tables show the failure
rates according to IEC 61508 depending on whether fail low / fail high was considered to be
dangerous detected or safe detected to:
6
These failures are not detected by internal diagnostics but because they lead to the safe state (e.g. by
reaching the user defined trip point) they are detected by the logic solver independent of the user defined
fail-safe state ("fail low" or "fail high").
exida.com
© GmbH
Stephan Aschenbrenner
more@turck.com • www.turck.com • 2015/04
Anhang – EXIDA-Report FMEDA Turck 04/07-14 R001
+ λ ) + 8 h = 159 years
total not part
6
6
+ λ + λ
sd su dd
67
high
6
+ λ + λ
sd su dd
233
low
Fail-safe state = Fail-safe state =
"fail high" "fail low"
73
233
44
315
53
159 years
TURCK 04-07-14 R001 V2R0.doc; February 8, 2013
67
239
44
315
53
159 years
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