Measurement and prediction of brush interface temperature at sliding electrical contacts

Binderless copper-graphite composite electrical brushes have been fabricated with a high-energy and high-rate pulse sintering technique. Experiments were conducted to measure the interface contact spot temperatures of homopolar pulse consolidated brushes for a rotor surface sliding speed of 40 m/s, an apparent brush current density of 180 A/cm/sup 2/, and a brush down force of 44.5 N. Thermocouples were embedded in the brush samples at positions from 0.36 to 0.51 mm above the brush/rotor interface, and temperatures were monitored until the thermocouples were destroyed. Temperature readings of the thermocouples varied significantly as the interface approached. A three-dimensional finite-element thermal analysis for the homopolar pulse consolidated (HPC) brush contact spot was performed by using the heat input obtained from the experiments. The analytical results are in good agreement with the experimental data.<
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