The research of fiber/graphite composite brush

A new type of composite brush which consists of property-modified graphite matrix and copper plated carbon fiber has been investigated. These brushes possess high current carrying capacity, excellent commutating performance and good wearing resistance as well as performance designability. In order to adapt different kinds of electrical machines such as 55 kW DC machine, 600,000 kW turbogenerator, 60 kW traction motor and 800 kW rolling machine, varied composite brushes were optimally designed by pretreating the fibers, modifying the graphite matrix and changing the distribution of the fibers. Results indicated an excellent performance of these brushes. For instance, the comparisons of composite brushes with commercial electrographite brush after more than 1200 hours dynamic test on a 551 kW DC machine showed that the current density had been increased by 4 times (0.36 MA/m/sup 2/), the width of the no sparking zone had been enlarged by 2-9 times and the mechanical loss had been decreased by 15-25%. In the meantime, the wear of the commutator was as usual. It means that such fiber composite brushes have great potential in improving the performance and structure of electrical machines.