Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Abstract

The wear and contact resistance of sliding contacts are typically researched with a pin-on-disk experiment that prevents dynamic excitation. However, in electrical machines, the brush clearance enables dynamic excitation, resulting in flexible body dynamics. To research the wear and contact resistance during dynamical excitation, an in-situ experimental approach is introduced here, with the influences of rotational speed, electrical current, and temperature being assessed. This research shows that a small wear rate and contact resistance are possible at 10,000 and 5000 RPM if the electrical current is higher than 3 A. It was also found that the contact resistance decreased with an increased ambient temperature, electrical current, and rotating speed, whereas the wear rate increased with the rotating speed at low current density and low ambient temperature.