Simplified determinations of heat transfer data for solids, applications to quality testing of electrical insulations

Summary The first part of the paper describes a simple steady state apparatus for measuring the thermal conductivity of plates of electrical insulations, plastics, etc. The measurement is quick, requiring approximately 5 min. The apparatus also enables one to determine the thermal capacity of the sample. The second part of the paper describes the k-meter, a new device for measuring the heat transfer coefficient through the insulation on metal bars such as generator coils. The method does not require any access to the inner conductor. The suitability of the k-meter for nondestructive thermal ageing investigations of e.g. generator insulations and for quality control, is demonstrated. In this respect k-value measurements might be a valuable complement to dielectric loss measurements.An Appendix gives details of the theory and error estimates.