What Is Heat Conduction Error and How Does It Affect Thermocouple Temperature Measurement?

In thermocouple measurements, heat is exchanged not only between the sensing junction and the measured medium but also along the probe sheath, thermocouple wires, and mounting structure. If this axial heat flow changes the thermal equilibrium around the sensing junction, the measured temperature may differ from the actual temperature at the target location. The magnitude of this error depends on temperature gradients, insertion depth, probe diameter, thermal conductivity, and heat-transfer conditions.