KROHNE OPTISWITCH 3x00C 2wire SIL EN - Manual (Page 9)

This function test is triggered by an interruption of the supply
cable for at least two seconds. Then a special warm-up
reaction of the current output is carried out which must be
recorded.
The test procedure is described in detail in the operating
instructions manual.
Test key on the signal conditioning instrument:
If a connected signal conditioning instrument with test key is
used for processing, the stated function test can be easily
carried out by pushing the test key. Suitable signal condition-
ing instruments are listed in chapter "Technical data" of the
operating instructions manual.
Note:
This test can be carried out only if the vibrating element is
uncovered.
1 .7 Safety-related characteristics
The failure rates of the electronics, the mechanical parts of the
transmitter as well as the process fitting are determined by an
FMEDA according to IEC 61508. The calculations are based
on component failure rates according to SN 29500. All values
refer to an average ambient temperature during the operating
time of 40 °C (104 °F).
For a higher average temperature of 60 °C (140 °F), the failure
rates should be multiplied by a factor of 2.5. A similar factor
applies if frequent temperature fluctuations are expected.
The calculations are also based on the specifications stated in
chapter "Planning".
After 8 to 12 years, the failure rates of the electronic
components will increase, whereby the derived PFD and PFH
values will deteriorate (IEC 61508-2, 7.4.7.4, note 3).
Mode switch on the sensor to "max."
Overflow protection
(max. operation)
Dry run protection
(min. operation)
λ
sd
49 FIT 39 FIT
λ
su
387 FIT 352 FIT
λ
dd
163 FIT 182 FIT
Basics
Service life
Failure rates
OPTISWITCH series 3000 • - two-wire 9
Functional safety
32745
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EN
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080414