WIKA TR21 Mode D'emploi page 21

10. Faults
Faults
Erroneous measured
values and response
times too long
Temporary or
intermittent
interruptions of the
measured value signal
Corrosion
Signal interference
Not possible to insert
the temperature sensor
into the protection tube
Leakage of process
media
at the connection
■
between the process
and the protection tube
on the junction of
■
the protection tube
with the temperature
sensor or on the
temperature sensor
WIKA operating instructions model TR21
Causes
Wrong mounting geometry, for
example mounting depth too
deep or heat dissipation too
high
Deposits on the protection tube
Cable break in connection
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 circuit
Earth circuit
Foreign bodies in the protection
tube
Damaged or contaminated
fastening threads of protection
tube or temperature sensor
Sensor dimension and those
of the inner diameter of the
protection tube do not match
Protection tube or sensor has
been bent or damaged during
installation
Error during installation or
defective seals
Damage, e.g. caused by
operating the protection tube
under a resonant vibration load
Measures
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 shielded connection leads,
increase in the distance to motors
and power lines
Elimination of potentials, use of
galvanically isolated barriers 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 5.1.1 and
5.1.2)
Safe operation of the plant can no
longer be guaranteed
(in the worst case, this might result in
a complete rupture of the protection
tube)
EN
21