5623B
Users Guide
6
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, contact
Fluke for assistance (see “How to Contact Fluke”). Be sure to have the model number and serial
number of your probe available.
Table 3. PRT Troubleshooting
Problem
Solution
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
tpw
.
Data changes less than 0.1 °C.
Slight mechanical shock can cause temperature errors less than 0.1 °C.
Data unstable.
•
If the data is unstable at the Triple Point of Water (TPW), check
connections for evidence of a bad connection. If the connector
appears to be in good condition and the connections are good, the
PRT may be damaged.
Contact Fluke for assistance (see “How to
Contact Fluke”).
•
If the data is unstable at high temperatures, it may be due to electrical
noise in the system. Reduce the temperature and observe the data.
If it is stable, 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 temperature measurements. A ground wire attached to the metal
sheath of the PRT may help to reduce electrical noise interference.
Temperature readout is different
than expected. For example, the
heat source is set at 150 °C, the
PRT measures 125 °C.
•
Measure the PRT resistance at TPW.
•
The PRT sensor may be shorted if the measured resistance at 0 °C is
significantly less than the probe’s nominal resistance. For example, a
probe whose nominal resistance is 100
Ω
but measures 70
Ω
at 0 °C.
• If the resistance of the PRT is only a few ohms, there may be a short
in the four lead-wires.
• If the PRT is open, the resistance will be “Out of Limits” or in the
kilohm or megohm range.
For more information or assistance,
Contact Fluke (see “How to
Contact Fluke”).