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.

The present invention relates to monolithic structures for use as an electrical contact. In particular, these structures are formed from a laminate alloy, which in turn is composed of a M.sub.n+1AX.sub.n compound. Electrical contact assemblies and electrical components having such contacts are also described herein. In some example, such monolithic structures display increased wear resistance, which is useful for sliding electrical contacts.

The present invention relates to monolithic structures for use as an electrical contact. In particular, these structures are formed from a laminate alloy, which in turn is composed of a M.sub.n+1AX.sub.n compound. Electrical contact assemblies and electrical components having such contacts are also described herein. In some example, such monolithic structures display increased wear resistance, which is useful for sliding electrical contacts.

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%.

Systems and methods to mitigate electrical voltage on a rotating plate are disclosed. An example grounding pen brush includes two or more bundles of conductive filaments that are separated from the others by a threshold distance.

The present invention is a sliding contact material having a composition of Cu of 6.0% by mass or more and 9.0% by mass or less, Ni of 0.1% by mass or more and 2.0% by mass or less, an additive element M of 0.1% by mass or more and 0.8% by mass or less, and the balance being Ag. The additive element M is at least one element selected from the group consisting of Sm, La and Zr. The present sliding contact material has a material structure in which dispersion particles containing an intermetallic compound containing at least both Ni and an additive element M are dispersed in an Ag alloy matrix. It is required that the ratio of a Ni content (% by mass) and a content of an additive element M (% by mass) (K.sub.Ni/K.sub.M) in the dispersion particles falls within a predetermined range. The present invention is an Ag alloy-based sliding contact material more excellent also in abrasion resistance than conventional ones, and a material adaptable to higher rotation numbers of micromotors.

The present invention is a sliding contact material having a composition of Cu of 6.0% by mass or more and 9.0% by mass or less, Ni of 0.1% by mass or more and 2.0% by mass or less, an additive element M of 0.1% by mass or more and 0.8% by mass or less, and the balance being Ag. The additive element M is at least one element selected from the group consisting of Sm, La and Zr. The present sliding contact material has a material structure in which dispersion particles containing an intermetallic compound containing at least both Ni and an additive element M are dispersed in an Ag alloy matrix. It is required that the ratio of a Ni content (% by mass) and a content of an additive element M (% by mass) (K.sub.Ni/K.sub.M) in the dispersion particles falls within a predetermined range. The present invention is an Ag alloy-based sliding contact material more excellent also in abrasion resistance than conventional ones, and a material adaptable to higher rotation numbers of micromotors.

An electrical machine with a brush commutator arrangement (1) is proposed. Brushes (3) and a commutator (5) are adapted and arranged such that, upon operating the electrical machine (1), the brush (3) and the commutator (5) are displaced relative to each other in a lateral displacement direction (7) and a contact surface (9) of the brush (3) mechanically contacts a contact surface (11) of the commutator (5) along an overlapping area (13) thereby generating an electrical contact. Accordingly, an electric current is transmitted between brush (3) and commutator (5) through the overlapping area (13). An orthogonal electrical conductivity of the brush (3) and/or the commutator (5) in a direction (25) orthogonal to a respective contact surface (9, 11) locally varies along the lateral displacement direction (7). An orthogonal electrical conductivity distribution in the brush (3) and/or the commutator (5) is adapted such that, even when operating the electrical machine at maximum allowable power, for at least 90% of all spatial configurations during displacing the brush (3) and the commutator (5) relative to each other, an electrical current density through the overlapping area (13) does not exceed 130% of a rated maximal average electrical current density through the brush commutator arrangement (1). Due to the specific variation of orthogonal electrical conductivity within the brush (3) or commutator (5), sparking and resulting wear in the proposed brush commutator arrangement (1) may be reduced.

An electrical machine with a brush commutator arrangement (1) is proposed. Brushes (3) and a commutator (5) are adapted and arranged such that, upon operating the electrical machine (1), the brush (3) and the commutator (5) are displaced relative to each other in a lateral displacement direction (7) and a contact surface (9) of the brush (3) mechanically contacts a contact surface (11) of the commutator (5) along an overlapping area (13) thereby generating an electrical contact. Accordingly, an electric current is transmitted between brush (3) and commutator (5) through the overlapping area (13). An orthogonal electrical conductivity of the brush (3) and/or the commutator (5) in a direction (25) orthogonal to a respective contact surface (9, 11) locally varies along the lateral displacement direction (7). An orthogonal electrical conductivity distribution in the brush (3) and/or the commutator (5) is adapted such that, even when operating the electrical machine at maximum allowable power, for at least 90% of all spatial configurations during displacing the brush (3) and the commutator (5) relative to each other, an electrical current density through the overlapping area (13) does not exceed 130% of a rated maximal average electrical current density through the brush commutator arrangement (1). Due to the specific variation of orthogonal electrical conductivity within the brush (3) or commutator (5), sparking and resulting wear in the proposed brush commutator arrangement (1) may be reduced.