WIKA TR10-B - Handbuch (Seite 15)

WIKA operating instructions resistance thermometers per EN 14597
3132465.01 07/2011 GB/D
15
GB
7. Maintenance and cleaning
7.1 Maintenance
This resistance thermometer is maintenance-free.
Repairs must only be carried out by the manufacturer.
7.2 Cleaning
CAUTION!
■ Clean the instrument with a moist cloth.
■ Electrical connections must not come into contact with moisture.
■ Wash or clean the dismounted instrument before returning it, in order to
protect personnel and the environment from exposure to residual media.
■ Residual media in dismounted instruments can result in a risk to persons, the
environment and equipment. Take sufficient precautionary measures.
For information on returning the instrument see chapter "9.2 Return".
8. Faults
Faults Causes Measures
No signal/ line breakage Mechanical load too high or
overtemperature
Replace probe or measuring insert with
a suitable design
Erroneous measured
values
Sensor drift caused by
overtemperature
Replace probe or measuring insert with
a suitable design
Sensor drift caused by chemical
attack
Use a design with thermowell
Erroneous measured
values (too low)
Entry of moisture into cable or
measuring insert
Replace probe or measuring insert with
a suitable design
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,
and surfaces must be isolated
Deposits on the sensor or thermowell Remove deposits
Measurement signal
"comes and goes"
Cable break in connecting cable or
loose contact caused by mechanical
overload
Replace probe or measuring insert
with a suitable design, for example
equipped with a 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 shielded connecting cables, and
increase the separation from motors
and power cables.
Earth circuits Eliminate potential differences by
using galvanically isolated transmitter
power supplies or transmitters.
7. Maintenance and cleaning / 8. Faults