Faults - WIKA TR10-L Betriebsanleitung

10. Faults

10. Faults
Faults
GB
No signal/
line break
Erroneous measured
values
Erroneous measured
values (too low)
Erroneous measured
values and response
times too long
Erroneous measured
values (of thermocouples)
Indication of the
measured value jumps
Corrosion
Signal interference
CAUTION!
If faults cannot be eliminated by means of the measures listed above, the
instrument must be shut down immediately, and it must be ensured that signal
is no longer present, and it must be prevented from being inadvertently put back
into service. In this case, contact the manufacturer.
If a return is needed, follow the instructions given in chapter 11.2 "Return".
20
Causes
Mechanical load too high or
overtemperature
Sensor drift caused by
overtemperature
Sensor drift caused by chemical attack Use of a suitable thermowell
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 modifed or wrong
thermowell material selected
Stray currents caused by electric felds
or earth loops
Earth loops
WIKA operating instructions models TR10-L, TC10-L (Ex d)
Measures
Replacement of the sensor or the
measuring insert with a suitable version
Replacement of the sensor or the
measuring insert with a suitable version
Replacement of the sensor or the
measuring insert with a suitable version
The temperature-sensitive area of the
sensor must be inside the medium, and
surfaces must be ungrounded
Remove deposits
Check polarity
Use of a suitable equalisation line
Replacement of the sensor or measuring
insert with a suitable design, for example
ftted with strain relief or a thicker
conductor cross-section
Analyse medium and then select a
more-suitable material or replace
thermowell regularly
Use of screened connecting cables,
increase in the distance to motors and
power lines
Elimination of potentials, use of
galvanically isolated transmitter supply
isolators or transmitters