WIKA TR12-M - Handbuch (Seite 22)

GB
14064370.01 08/2013 GB/D
WIKA operating instructions models TR12, TC12 22
8. Faults
Faults Causes Measures
No signal/
line break
Mechanical load too high or overtem-
perature
Replacement of the sensor or the meas-
uring insert with a suitable version
Erroneous measured
values
Sensor drift caused by overtemperature Replacement of the sensor or the meas-
uring insert with a suitable version
Sensor drift caused by chemical attack Use of a suitable thermowell
Erroneous measured
values (too low)
Entry of moisture into cable or measur-
ing insert
Replacement of the sensor or the
measuring insert with a suitable version
Erroneous measured
values and response
times too long
Wrong mounting geometry, for example
mounting depth too deep or heat
dissipation too high
The temperature-sensitive area of the
sensor must be inside the medium
Deposits on the sensor or thermowell Remove deposits
Erroneous measured
values (of thermocouples)
Parasitic voltages (thermal voltages,
galvanic voltage) or wrong equalisation
line
Use a suitable equalisation line
Measurement signal -
“comes and goes”
Cable break in connecting cable or
loose contact caused by mechanical
overload
Replacement of the sensor or
measuring insert with a suitable design,
for example fitted with strain relief or a
thicker conductor cross-section
Corrosion Composition of the medium not
as expected or modified or wrong
thermowell material selected
Analyse medium and then select a
more suitable material or replace
thermowell regularly
Signal interference Stray currents caused by electric fields
or earth loops
Use of screened connecting cables,
increase in the distance to motors and
power lines
Earth circuits Elimination of potentials, use of
galvanically isolated transmitter supply
isolators or transmitters
CAUTION!
If faults cannot be eliminated by means of the measures listed above, shut
down the instrument immediately, and ensure that pressure and/or signal are no
longer present, and secure the instrument from being put back into operation
inadvertently.
In this case, contact the manufacturer.
If a return is needed, follow the instructions given in chapter 9.2 “Return”.
8. Faults