Thermocouples - What temperature are they measuring?

Mold temperatures are often used as a predictor of the state of continuous casting systems. There is a finite error involved in thermocouple thermometry, due to many factors, including the very presence of the thermocouple void. The classic problem of perturbing the system, while attempting to measure a property of the system, manifests itself here as distortions of temperature fields resulting in erroneous measurements. We investigated this error using both finite element modeling and experimentation, under both steady state and transient conditions and determined the error associated with void diameter, distance from surfaces, and distance between thermocouples.