Common fault phenomena and treatment methods of industrial thermocouples

Correct use of industrial thermocouples not only allows for accurate temperature readings, ensuring product quality, but also saves material consumption of thermocouples, thus saving costs while ensuring product quality. In addition to common errors caused by reversed compensation wires, incorrect usage, and loose connections (solution: use compensation wires correctly and tighten the terminals), incorrect installation, thermal conductivity, and time lag are the main errors encountered during the use of thermocouples.
1. Fault phenomenon: The thermoelectric potential is lower than the actual value (the display instrument indicates a low value)
Possible cause: Short circuit of the thermoelectric electrode
Solution: Identify the cause of the short circuit, if due to moisture, drying is required; if due to insulation damage, the insulator needs to be replaced; clean accumulated dust; short circuit between compensation wire lines: locate the short circuit point, strengthen insulation or replace the compensation wire.
2. Fault phenomenon: The thermoelectric potential is lower than the actual value (the display instrument indicates a low value)
Possible cause: Deterioration of the industrial thermocouple thermoelectric electrode
Solution: If length permits, cut off the deteriorated section and re-weld, or replace with a new thermocouple.
3. Fault phenomenon: The thermoelectric potential is lower than the actual value (the display instrument indicates a low value)
Possible cause: Reversed polarity of the compensation wire and industrial thermocouple
Solution: Reconnect correctly.
4. Fault phenomenon: The thermoelectric potential is lower than the actual value (the display instrument indicates a low value)
Possible cause: Incompatibility between the compensation wire and the industrial thermocouple
Solution: Replace with a compatible compensation wire.
5. Fault phenomenon: The thermoelectric potential is lower than the actual value (the display instrument indicates a low value)
Possible cause: Improper installation position or insufficient insertion depth of the industrial thermocouple
Solution: Reinstall according to specifications.
6. Fault phenomenon: The thermoelectric potential is lower than the actual value (the display instrument indicates a low value)
Possible cause: Cold junction temperature compensation of the industrial thermocouple does not meet requirements
Solution: Adjust the cold junction compensator.
7. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: Incompatibility between the industrial thermocouple and the display instrument
Solution: Make the industrial thermocouple and display instrument compatible.
8. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: Incompatibility between the compensation wire and the industrial thermocouple
Solution: Replace with a compatible compensation wire.
9. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: DC interference signal entering
Solution: Eliminate DC interference.
10. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: Unstable thermoelectric potential output
Solution: Tighten the terminal screws where the industrial thermocouple connects to the thermoelectric electrode.
11. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: Insulation damage in the measurement circuit of the industrial thermocouple, causing intermittent short circuits or grounding.
Solution: Identify the fault point and repair the insulation.
12. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: The industrial thermocouple is not securely installed or external vibrations.
Solution: Secure the industrial thermocouple, eliminate vibrations, or take damping measures.
13. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: The thermoelectric electrode is partially broken.
Solution: Repair or replace the industrial thermocouple.
14. Fault phenomenon: The thermoelectric potential is higher than the actual value (the display instrument indicates a high value)
Possible cause: External interference (AC leakage, electromagnetic induction, etc.)
Solution: Identify the source of interference and take shielding measures.
15. Fault phenomenon: Large thermoelectric potential error
Possible cause: Deterioration of the thermoelectric electrode
Solution: Replace the thermoelectric electrode.
16. Fault phenomenon: Large thermoelectric potential error
Possible cause: Improper installation position of the industrial thermocouple
Solution: Change the installation position.
17. Fault phenomenon: Large thermoelectric potential error
Possible cause: Dust accumulation on the surface of the protective tube
Solution: Remove accumulated dust.