Faults - WIKA TR21-A Mode D'emploi

10. Faults

10. Faults
Faults
No signal/line break
Erroneous measured
values
Erroneous measured
values (too low)
Erroneous measured
values and response times
too long
Indication of the measured
value jumps
Corrosion
Signal interference
Not possible to insert the
temperature sensor into
the thermowell
Leakage of process media
at the connection between
■
the process and the
thermowell
on the junction of the
■
thermowell with the
temperature sensor or on
the temperature sensor
WIKA operating instructions model TR21
Causes
Mechanical load too high or
overtemperature
Sensor drift caused by
overtemperature
Sensor drift caused by chemical
attack
Entry of moisture into cable
Wrong mounting geometry, e.g.
mounting depth too deep or heat
dissipation too high
Deposits on the thermowell
Cable break in connecting cable
or loose contact caused by
mechanical overload
Composition of the medium not as
expected or modified
Stray currents caused by electric
fields or earth loops
Earth circuits
Foreign bodies in the thermowell
Damaged or contaminated
thermowell or temperature sensor
fastening thread
Sensor dimension and those of the
inner diameter of the thermowell do
not match
Thermowell or sensor has been
bent or damaged during installation
Error during installation or defective
seals
Damage, e.g. caused by operating
the thermowell under a resonant
vibration load
Measures
Replace probe or measuring
insert with a suitable design
Replace probe or measuring
insert with a suitable design
Analyse the medium
Use the appropriate IP
protection
The temperature-sensitive
area of the sensor must be
inside the medium, and surface
measurements must be
ungrounded
Remove deposits
Replace the sensor or use
thicker conductor cross-section
Analyse the medium
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
Remove foreign bodies
Clean or recut the thread
Check order documentation
Return for repair
Check the seal, check the
tightening torques (see chapter
6.1.1 and 6.1.2)
Safe operation of the plant can
no longer be guaranteed
(in the worst case, this might
result in a complete rupture of
the thermowell)
EN
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