A brush for a starter-generator includes a first carbon block, a second carbon block, a terminal lug, and a plurality of brush leads. Each carbon block has an outboard edge and an inboard edge. Each carbon block includes a front carbon wafer and a rear carbon wafer. Front brush leads connect the terminal lug with the front carbon wafers of the respective carbon blocks adjacent the inboard edges of the respective carbon blocks. Rear brush leads connect the terminal lug with the rear carbon wafers of the respective carbon blocks adjacent the outboard edge of the respective carbon blocks.

A socket module of a rotatable socket device includes a first conductor, a second conductor, an insulator that is arranged to separate the first conductor from the second conductor, and a plurality of terminal sets. The first conductor includes a first base and a plurality of central rods connected to the first base. The second conductor includes a second base and a plurality of tubes connected to the second base. The tubes are respectively sleeved around the central rods. Each of the central rods and the corresponding tube are separated from each other by the insulator. The terminal sets are respectively rotatable along the central rods within a range of 360 degrees. Each of the terminal sets includes a first terminal rotatably contacting the corresponding central rod and a second terminal rotatably contacting the tube that is sleeved around the corresponding central rod.

A carbonaceous material is fabricated by a mixture of carbon powder and a binder. 10% by weight or more and 60% by weight or less of metal powder to the fabricated carbonaceous material is mixed. The mixed carbonaceous material and metal powder are pressurized and formed. A brush base material is fabricated by burning of the pressurized and formed carbonaceous material and metal powder. The fabricated brush base material is impregnated with oil. An impregnation rate of the oil to the mixed carbonaceous material and metal powder may be 0.5% by weight or more, for example.

A carbonaceous material is fabricated by a mixture of carbon powder and a binder. 10% by weight or more and 60% by weight or less of metal powder to the fabricated carbonaceous material is mixed. The mixed carbonaceous material and metal powder are pressurized and formed. A brush base material is fabricated by burning of the pressurized and formed carbonaceous material and metal powder. The fabricated brush base material is impregnated with oil. An impregnation rate of the oil to the mixed carbonaceous material and metal powder may be 0.5% by weight or more, for example.

A system for monitoring the wear state of a carbon brush of a brush holder assembly in which the length of the carbon brush is diminished from an initial length as an end of the carbon brush wears away during use. The system includes a wear state monitor, including a sensor, coupled to the carbon brush. The wear state monitor is configured to rotate as the length of the carbon brush diminishes. The sensor is configured to measure an angular displacement of the wear state monitor as the wear state monitor rotates. The measured angular displacement of the wear state monitor correlates to an amount of diminution in the length of the carbon brush.

A system for monitoring the wear state of a carbon brush of a brush holder assembly in which the length of the carbon brush is diminished from an initial length as an end of the carbon brush wears away during use. The system includes a wear state monitor, including a sensor, coupled to the carbon brush. The wear state monitor is configured to rotate as the length of the carbon brush diminishes. The sensor is configured to measure an angular displacement of the wear state monitor as the wear state monitor rotates. The measured angular displacement of the wear state monitor correlates to an amount of diminution in the length of the carbon brush.

Provided is a brushed motor in which noise in a high rotational speed range is effectively decreased. A bar-shaped flat attachment 28 of synthetic resin is inserted along an axial line L into an opening of a slot 16 formed in a core 14 of a rotor 7, and fixed with respect to the core 14 and/or windings 17 using adhesive agent. The flat attachment 28 has side surfaces 28b and an inner peripheral surface 28c. The side surfaces 28b are engaged from an inner peripheral side with inclined surfaces 15a of teeth 15 adjacent to each other across the opening of the slot 16. The inner peripheral surface 28c of the flat attachment 28 has two ridges 28d protruding therefrom which are abutted against the windings 17. The flat attachment 28 closes the opening of the slot 16 and shapes an outer peripheral surface 14a of the core 14 into a flat cross sectional shape suitable for suppression of wind noise.

Provided is a brushed motor in which noise in a high rotational speed range is effectively decreased. A bar-shaped flat attachment 28 of synthetic resin is inserted along an axial line L into an opening of a slot 16 formed in a core 14 of a rotor 7, and fixed with respect to the core 14 and/or windings 17 using adhesive agent. The flat attachment 28 has side surfaces 28b and an inner peripheral surface 28c. The side surfaces 28b are engaged from an inner peripheral side with inclined surfaces 15a of teeth 15 adjacent to each other across the opening of the slot 16. The inner peripheral surface 28c of the flat attachment 28 has two ridges 28d protruding therefrom which are abutted against the windings 17. The flat attachment 28 closes the opening of the slot 16 and shapes an outer peripheral surface 14a of the core 14 into a flat cross sectional shape suitable for suppression of wind noise.

Devices for discharging ground currents, more particularly in wind turbines, from electrical machines. The devices have a grounding ring mounted on a rotor of the electrical machine and a sliding contact connectable to ground and that is in contact with the grounding ring. The sliding contact element has a carbon brush with a bulk density between 1.1 and 1.4 g/cm.sup.3, and the carbon brush contains a metal inclusions composed of silver, the silver proportion being between 1 and 8%.

Devices for discharging ground currents, more particularly in wind turbines, from electrical machines. The devices have a grounding ring mounted on a rotor of the electrical machine and a sliding contact connectable to ground and that is in contact with the grounding ring. The sliding contact element has a carbon brush with a bulk density between 1.1 and 1.4 g/cm.sup.3, and the carbon brush contains a metal inclusions composed of silver, the silver proportion being between 1 and 8%.