A modified digital proportional-integral-derivative (PID) temperature controller for thermal properties measurements is described. Data are presented to illustrate the approach to equilibrium and the degree of stability at equilibrium The controller is being used to control the heating elements of a high temperature guarded-hot-plate to within approximately 10 mK.
Hust, J.G., B.J. Filla, J.A. Hurley and D.R. Smith."An Automated High Temperature Guarded-Hot-Plate Apparatus for Measuring Thermal Conductivity of Insulation Between 300 and 800 K" (to be published as a National Bureau of Standards Report).
