Fluke 5626/5628 - Manual (Page 21)

8 Troubleshooting
8.1 Troubleshooting
In the event that the probe appears to function abnormally, this section may
be of use in solving the problem. Several possible problem conditions are
described along with likely causes and solutions. If a problem arises, please
read this section carefully and attempt to understand and solve the problem.
If the probe seems faulty or the problem cannot otherwise be solved, con-
tact an Authorized Hart Scientific Service Center (see Section 1.3) for assis-
tance. Be sure to have the model number and serial number of your probe
available.
Problem Causes and Solutions
Data changes greater than
0.1°C are observed • Mechanical shock can cause temperature errors as great
as 0.5°C. If this is observed, first measure and record the
R
tp.
Next anneal the PRT at 660°C overnight. Measure the
R
tp
again. The annealing should decrease the R
tp
. If the
R
tp
is stable, recalibrate the PRT.
Data changes less than
0.1°C • Slight mechanical shock can cause temperature errors
less than 0.1°C. If this is observed, first measure and re-
cord the R
tp.
Next anneal the PRT at 660°C overnight.
Measure the R
tp
again. The annealing should decrease
the R
tp
. Repeat the annealing, R
tp
measurement cycle
several times. When the R
tp
is stable, recalibrate the PRT.
If the R
tp
does not stabilize, contact an Authorized Hart
Scientific Service Center (see Section 1.3).
• Oxidation of the platinum sensor may occur after pro-
longed use between 200 – 450°C. This oxidation will
demonstrate itself by an increase in R
tp
of less than
0.1°C. To reduce the effects of oxidation, anneal the PRT
at 600 – 661°C overnight (12 hr.). Measure the R
tp
again.
Repeat the annealing, R
tp
measurement cycle several
times This annealing process should return R
tp
to within
calibration tolerances. If the R
tp
is within calibration tol-
erance, the PRT is usable. If the R
tp
is not within calibra-
tion tolerance, but it is stable, recalibrate the PRT.
Data unstable • If the data is unstable at the Triple Point of Water (TPW),
check the connector. If the connector is correct, contact
an Authorized Hart Scientific Service Center (see Section
1.3). The PRT may be damaged and need repair.
• If the data is unstable at high temperatures, it may be
due to electrical noise in the system. Reduce the temper-
ature and observe the data. If it is stable, electrical noise
is interfering with the measurements at high tempera-
tures. Check the grounding of the readout device and
the heat source. A faulty ground on either device could
interfere with high temperature measurements. A
ground wire attached to the metal sheath of the PRT
may help to reduce electrical noise interference.
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8
Troubleshooting