Standard Resistors with Small Load Corrections
G. H. Briggs · Metrologia · 1969
The factors which contribute to the variation of resistance with power dissipated in standard resistors are investigated in some detail. In addition to the change in resistance to be expected from a uniform temperature rise there are effects which result from a non-uniform temperature distribution. An important contribution may arise from the inclusion of copper terminations in the defined resistance. The relevant heat transfer theory is outlined and applied to the design of resistors with forced-convection oil cooling. Such cooling applied to a conventional 1 Ω resistance standard reduced the temperature rise with power dissipated by some 25 times.