A slip ring body for electrically contacting an asynchronous machine includes first and second slip rings rigidly connected to one another, with at least two conductor bars fastened to each of the slip rings. At least one of the slip rings has a recess for passage of the conductor bars of the other slip ring and defining around the recess a first region in which air is at least partially present and which has a magnetic conductivity that is lower than a magnetic conductivity in a second region in which the conductor bars to the one slip ring are fastened, or which second region is embodied for contacting with an energy-transmitting brush. The first and second regions are not made of copper. The recess defines an opening cross-sectional area which is greater than a cross-sectional area of the conductor bars fastened to the one slip ring.

A DC motor is provided that can suppress a commutator from wearing. A DC motor including a commutator formed of copper or a copper alloy of 99% or more copper, and a brush pressed against and in contact with the commutator, wherein the brush is composed of a sintered compact including graphite and copper powder, hard compound particles higher in hardness than any of the copper or the copper alloy and the graphite or the copper powder are contained in at least one of the commutator and the brush and are scattered on or near a contact surface of the commutator with the brush at least during use.

The invention relates to a shaft-grounding ring which is used to remove induced voltages or electric charges from a first machine element (68), preferably from a shaft, into a second machine element (69) and has an annular housing (1), which consists of electrically conductive material and is conductively connected to the one machine element (68, 69) and has an electrically conductive connection to at least one discharging element (8). The discharging element consists of an electrically conductive material and has an electrically conductive connection to the other machine element. The discharging element (8) is a disk-shaped discharging body that extends at least over part of the circumference thereof.

A current collector and a conductor line system having such a current collector. The current collector has a holder and a carbon brush arranged in carbon brush support movable relative to holder in a feed direction from and to the conductor line. The carbon brush is movable in a feed direction from and to conductor line. A better and reliable guiding of the carbon brush on the conductor line and simpler design of the current collector, uses a current collector in which the carbon brush is additionally movable in a transverse direction running essentially across the longitudinal direction, a spring element being provided between the carbon brush and holder.

A slip ring assembly including a plurality conducting disks spaced-apart and stacked mounted along a common rotation axis, each being electrically connectable and fixedly securable to a generator mounted in a rotatable nacelle of a wind turbine so that a rotation of the rotatable nacelle triggers a rotation of the conducting discs; and a plurality of slip ring devices, each being electrically connectable and mechanically securable to a fixed electrical distribution conductor mounted to a fixed pole so as to have a fixed position relative to the fixed pole, and each of the plurality of the slip ring devices having upper and conducting fingers arranged so as to rotatably receive a respective conducting disk therebetween and to provide an electrical connection between the conducting disks and the slip ring device during rotation of the nacelle.

A DC motor is provided for use in a starter that starts an ermine. The DC motor includes a commutator and a brush. The commutator is formed of copper or a copper alloy whose copper percentage content is higher than or equal to 99 mass %. The brush is arranged in sliding contact with a surface of the commutator. Moreover, the brush is formed of a sintered compact that contains graphite, copper and at least one metal sulfide solid lubricant. The percentage content of copper in the sintered compact is 30-70 mass %. The at least one metal sulfide solid lubricant includes tungsten disulfide. The percentage content of tungsten disulfide in the sintered compact is higher than or equal to 6.5 mass %.

A starter includes a motor configured with a direct current motor. The direct current motor has a brush and a commutator. The brush is a sintered material formed of graphite and a copper powder. The commutator is formed of either copper or a copper alloy that has a copper content of 99% or more. A surface of is a sliding portion of the commutator which has sliding movement with the brush is provided with a graphite cover-layer that contains graphite as a main component. The graphite cover-layer contains a hard compound which has a Vickers hardness higher than 10 GPa and a metal sulfide solid lubricant.

A DC motor is provided that can suppress a commutator from wearing. A DC motor including a commutator formed of copper or a copper alloy of 99% or more copper, and a brush pressed against and in contact with the commutator, wherein the brush is composed of a sintered compact including graphite and copper powder, hard compound particles higher in hardness than any of the copper or the copper alloy and the graphite or the copper powder are contained in at least one of the commutator and the brush and are scattered on or near a contact surface of the commutator with the brush at least during use.

The invention relates to a shaft-grounding ring which is used to remove induced voltages or electric charges from a first machine element (68), preferably from a shaft, into a second machine element (69) and has an annular housing (1), which consists of electrically conductive material and is conductively connected to the one machine element (68, 69) and has an electrically conductive connection to at least one discharging element (8). The discharging element consists of an electrically conductive material and has an electrically conductive connection to the other machine element. The discharging element (8) is a disk-shaped discharging body that extends at least over part of the circumference thereof.

A device {i.e., a slip-ring or a homopolar motor/generator) (40, 50, 80) is adapted to provide electrical contact between a stator and a rotor (41, 83), and includes: a current-carrying brush-spring (31, 84) mounted on the stator, and having two opposite surfaces; a fibrous brush assembly (35, 69) mounted on the conductor, the brush assembly having a bundle of fibers (36, 71) arranged such that the tips of the fibers will engage the rotor for transferring electrical current between the stator and rotor; a ribbon (33, 85) of superconducting material mounted on each opposite surface of the current-carrying brush-spring and communicating with the stator and the brush assembly; and another ribbon (29, 86) of superconducting material mounted on the rotor. The device is submerged in a cryogenic fluid at a temperature below the transition temperatures of the superconducting materials such that the electrical resistivity of the device will be reduced and the current-transfer capability of the device will be increased.