Limiting Design Parameters For Cooled, High Speed, High Current Density Sliding Contacts

For advanced design of lightweight multi-megawatt dc continuous duty generators, high speed and high current density must be obtained in the sliding contacts. Limiting design parameters must be recognized to direct research and analysis toward a successful design. A combination of electrical heating and sliding friction produces an intense heat-release in the small volume at the brush-rotor interface, thereby reaching upper temperature limits in a short time period. Coolant selection and application must not degrade other performance criteria while successfully removing heat from the brush-rotor interface. Component design and material selection for the brush, rotor; and coolant must be compatible and meet design limits for stress, temperature, heat transfer, wear, friction, mass, and size. Successful design criteria have been developed to meet each of these design limitations; however, research is continuing to explore higher performance designs.