7 Troubleshooting

7.1 Troubleshooting

In the eventthat the probe appears to function abnormally, this section may be

of use in solvingthe problem. Several possible problem conditions are de-

scribed along with likelycauses and solutions. If a problem arises, please read

thissection carefully and attempt to understand and solve the problem. If the

probe seems faultyor the problem cannot otherwise be solved, contact an Au-

thorized Hart Scientific Service Center (see Section 1.3) for assistance. Be sure

to havethe model number and serial number of your probe available.

Problem Causesand Solutions
Datachanges greater than 0.1°C
areobserved
•Mechanicalshock can cause temperature errors as great as 0.5°C. If this
isobserved, first measure and record the Rtp.
Datachanges less than 0.1°C •Slightmechanical shock can cause temperature errors less than 0.1°C.
Dataunstable •Ifthe data is unstable at the Triple Point of Water (TPW), check the con-
nector.If the connector is correct, contact an Authorized Hart Scientific
ServiceCenter (see Section 1.3). The PRT may be damaged.
•Ifthe data is unstable at high temperatures, it may be due to electrical
noisein the system. Reduce the temperature and observe the data. If it
isstable, electrical noise is interfering with the measurements at high
temperatures.Check the grounding of the readout device and the heat
source.A faulty ground on either device could interfere with high tem-
peraturemeasurements. A ground wire attached to the metal sheath of
thePRT may help to reduce electrical noise interference.
Temperaturereadout different than
expected,e.g. the heat source is set
at150°C, the PRT measures 125°C.
•Measurethe PRT resistance at TPW.
•Ifthe resistance of the PRT is less than the rated resistance, e.g. 70 Ω,
theremay be a short in the sensor. Contact an Authorized Hart Scientific
ServiceCenter (see Section 1.3).
•Ifthe resistance of the PRT is only a few ohms, there may be a short in
thefour lead-wires. Contact an Authorized Hart Scientific Service Center
(seeSection 1.3).
•Ifthe PRT is open, the resistance will be “Out of Limits” or in the
kilo-ohmor mega-ohm range. Contact an Authorized Hart Scientific Ser-
viceCenter (see Section 1.3).
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7Troubleshooting