Design of Brush Gear for High Current Pulses and High Rubbing Velocities

This paper describes the mechanical brush gear designed for carrying the 1.6 million-ampere 1-second pulses from the rotors of the Canberra homopolar generator. Current density in the copper graphite brushes rises to about 10 000 A/in2 at full current. The brushes are also required to operate at rubbing speeds of up to 33 000 ft/min. The experiments that were made to set the design limits for the brushes and the results obtained from these experiments are described; the design requirements and details of the brush gear as manufactured are given; and their operation in the homopolar generator is discussed.