What are the Main Causes of Errors in Measurements with Thermocouples?

What are the Main Causes of Errors in Measurements with Thermocouples? The main sources of errors which can arise while measuring the temperature with thermocouples are the following:

  1. Connection of thermocouple to the measuring device with an unsuitable cable
  2. Inversion of polarity in the connections - Parasitic EMF
  3. Incorrect compensation of the reference junction.
  • It is imperative that all of the connections between the thermocouples and the measuring instruments be made using cables that are appropriately adjusted.
  • There are compensated cables available for every type of thermocouple, and the conditions of operation are the only factor that should influence the choice of insulation and diameters
  • Every compensation and/or extension cable for thermocouples has a color that identifies not only the kind of thermocouple but also the polarity of the thermocouple.
  • As a result, it is essential to ensure that the polarities of any connections that you make are maintained consistently.
  • When making connections between thermocouples and measuring equipment, it is best practice to utilize the specialized devices with compensated contacts that stop polarity inversion and to make as few junctions as feasible.
  • When using thermocouples that have grounded measurement junctions, there is a possibility that parasitic emf will be transferred from the thermocouple to the measuring equipment.
  • In addition, because the signal from the thermocouple is measured in millivolts, it is very susceptible to being influenced or disrupted in any way. Because of this, it is recommended to make use of thermocouples that have measurement junctions that are insulated.
  • As measuring with thermocouples necessitates the adjustment of the reference junction. It is critical that the measuring device carry out this process appropriately.