Carbone of America, a leader in power and signal transfer solutions, has redesigned the phase and ground brush holders for Hitachi generators installed in the GE fleet of 1.5 MW wind turbines. The new brush rigging assembly is a totally reengineered system, designed to reduce wear, maintenance and downtime in the long term. The brush holders are plug-and-play, so that uptower installation is fast, simple, and requires no modifications to the generator. The mass produced holders, die-cast from bronze alloy, are sturdy and built to withstand rigorous field use and turbine maintenance without sustaining damage. The radial-mounted brush holders were engineered to eradicate the previous reaction and trailing configuration and improve load sharing and equal wear rates between brushes. The brush dimensions were changed to provide equal surface area for the same energy transmission. The ratios of brush coverage to slip-ring diameter, width, and helical groove, have been optimized for peak performance.
The constant-force style brush pressure systems—200g/cm2 applied to the well-known carbon brush grade CG626—provide extremely low wear rates and minimal ring wear over long-term operation. They exert consistent force to keep all brushes in constant contact with the high-speed rotating slip rings for the best possible distribution of current between the four-phase (power) brushes. Upgraded brush terminals carry continuous high loadings; bolted connections ensure continuous, even current distribution between brushes in a phase group. Carbone of America’s brush rigging also incorporates a reliable indication system to alert when brushes become worn. The micro switch system, already widely used in the field, has proven to be dependable. For more information contact Roy Douglas, technical manager, at (973) 299-4518 or roy.douglas@carbonelorraine.com. Visit online at www.carbonebrush.com.
