WIKA TR21 Mode D'emploi page 21

10. Faults
WARNING!
Physical injuries and damage to property and the environment caused
by hazardous media
Upon contact with hazardous media (e.g. oxygen, acetylene, flammable
or toxic substances), harmful media (e.g. corrosive, toxic, carcinogenic,
radioactive), and also with refrigeration plants and compressors, there is a
danger of physical injuries and damage to property and the environment.
Should a failure occur, aggressive media with extremely high temperature
and under high pressure or vacuum may be present at the instrument.
▶ For these media, in addition to all standard regulations, the appropriate
existing codes or regulations must also be followed.
For contact details see chapter 1 „General information" or the back page of
the operating instructions.
In the case of critical installations, we recommend calculating the harmonic frequency of
the thermowell according to Dittrich/Klotter. This engineering service is offered by WIKA.
Faults
No signal/cable break
Erroneous measured
values
Erroneous measured
values (too low)
Erroneous measured
values and response
times too long
Temporary or
intermittent
interruptions of the
measured value signal
Corrosion
Signal interference
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, for
example mounting depth too
deep or heat dissipation too
high
Deposits on the thermowell
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
Measures
Replace the sensor with a suitable
version
Replace the sensor with a suitable
version
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 shielded connection leads,
increase in the distance to motors
and power lines
Elimination of potentials, use of
galvanically isolated barriers or
transmitters
EN
21