The effect of contact temperature on the performance of a high current density current collection system

Abstract

When current flows through sliding contacts, the flash temperature can be estimated analytically from Jaeger's equation, by summing the effects due to the generation of frictional and electrical heat. The estimation of the flash temperature at the interface requires knowledge of a number of parameters. Because of the number of variables involved, it is necessary to make assumptions regarding certain of these parameters. This makes it difficult to achieve accurate results. One major factor in the analysis is the hardness of the material, which is generally assumed to be constant over the temperature range. However, the rise in temperature will degrade the brush hardness and, according to the analysis, this may be expected to affect the estimated flash temperature. In this paper, the flash temperature is estimated for a range of current densities and the effect of brush softening at higher temperatures is included in the analysis.