WIKA RTD Mode D'emploi page 19

6. Faults
Should a failure occur, aggressive media with extremely high temperature
and under high pressure or vacuum may be present at the instrument.
▶ For these media, in addition to all standard regulations, the appropriate
existing codes or regulations must also be followed.
▶ Wear the required protective equipment (depending on the application; the
thermometer itself is basically not dangerous).
For contact details, please see chapter 1 "General information" or the back
page of the operating instructions.
Faults
No signal/cable break
Erroneous measured
values
Erroneous measured
values (too low)
Erroneous measured
values and response
times too long
Erroneous measured
values
(of thermocouples)
Display of measured
value jumps
Corrosion
Signal interference
WIKA operating instructions RTD and TC
Causes
Mechanical load too high or
overtemperature
Sensor drift caused by
overtemperature
Sensor drift caused by chemical
attack
Entry of moisture into cable or
measuring insert
Wrong mounting geometry, for
example mounting depth too
deep or heat dissipation too high
Deposits on the sensor or
thermowell
Parasitic voltages (thermal
voltages, galvanic voltage) or
wrong equalisation line
Cable break in connecting cable
or loose contact caused by
mechanical overload
Composition of the medium not
as expected or modified or wrong
thermowell material selected
Stray currents caused by electric
fields or earth loops
Earth loops
Measures
Replace probe or measuring insert
with one of a suitable design
Replace probe or measuring insert
with one of a suitable design
Use a suitable thermowell.
Replace probe or measuring insert
with one of a suitable design
The temperature-sensitive
area of the sensor must be
inside the medium, and surface
measurements must be ungrounded
Remove deposits
Use suitable compensating cable
Replace probe or measuring insert
with a suitable design, for example
equipped with a strain relief or a
thicker conductor cross-section
Analyse medium and then select a
more suitable material or replace
thermowell regularly
Use shielded connecting cables,
and increase the distance to
motors and power cables
Eliminate potential differences by
using galvanically isolated barriers
or transmitters
EN
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