Maintenance And Cleaning; Faults - WIKA RTD Operating Instructions Manual

10. Maintenance and cleaning / 11. Faults

10. Maintenance and cleaning

10.1 Maintenance
These thermometers are maintenance-free.
Repairs must only be carried out by the manufacturer.
GB
10.2 Cleaning
CAUTION!
Clean the instrument with a moist cloth. This applies in particular to thermometers
■
with a housing made of plastic and cable probes with plastic-insulated connection
lead, to ensure that any risk of electrostatic discharge is avoided.
Electrical connections must not come into contact with moisture.
■
Wash or clean the dismounted instrument before returning it, in order to protect
■
staff 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 "12.2 Returns".

11. Faults

Faults
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)
Measurement signal -
"comes and goes"
36
Causes
Mechanical load too high or
overtemperature
Sensor drift caused by
overtemperature
Sensor drift caused by chemical
attack
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
WIKA operating instructions RTD and TC, intrinsically safe designs
Measures
Replace probe or measuring insert with
a suitable design
Replace probe or measuring insert with
a suitable design
Use a design with thermowell
Replace probe or measuring insert with
a suitable design
Temperature-sensitive area of the
sensor must be inside the medium, and
surfaces must be isolated.
Remove deposits
Use a suitable equalisation line
Replace probe or measuring insert
with a suitable design, for example
equipped with a strain relief or a thicker
conductor cross-section