# US 10,480,490 B2 · Lightning current transfer unit for a wind turbine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,480,490 B2 - Document ID: US10480490B2 - Status: Granted - Kind: B2 - Application number: 15/536,302 - Filed: 2015-12-18 - Published: 2017-12-07 - Granted: 2019-11-19 - Earliest claimed: 2014-12-18 - Assignees: Vestas Wind Systems A/S - Applicants: Vestas Wind Systems A/S - Inventors: Anders Niels Hansen; Morten Bagger Søgaard; Claus Grøn Lyngby; Gert Lading - Web page: https://patentgrep.com/patent/US10480490B2 ## CPC - F03D 80/30: Lightning protection - F03D 1/0675: {of the blades} - F03D 1/0691: {of the hub} - F05B 2240/14: Casings, housings, nacelles, gondels or the like, protecting or supporting assemblies there within - F05B 2240/221: with horizontal axis - F05B 2260/502: involving springs - Y02E 10/72: Wind turbines with rotation axis in wind direction - F03D: WIND MOTORS - F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A lightning current transfer unit for a wind turbine, the wind turbine comprising a first part and a second part being rotatable relative to each other, wherein the lightning current transfer unit is arranged to provide electrical contact between the first and second parts, the lightning current transfer unit comprising: a first current transfer portion comprising a first slider and configured to be electrically coupled to a first electrically conducting slideway of the first part of the wind turbine, the first slider being rotatable relative to the first slideway; a second current transfer portion configured to be electrically coupled to an electrically conducting portion of the second part of the wind turbine; a first main spring biasing the first slider towards the first slideway; wherein the first slider comprises: a primary contact biased towards the first slideway by the first main spring; a secondary contact arranged to move relative to the primary contact; and a secondary spring arranged between the first main spring and the secondary contact such that the secondary spring biases the primary contact away from the first slideway and biases the secondary contact towards the first slideway. ## Claims ### Claim 1 A lightning current transfer unit for a wind turbine, the wind turbine comprising a first part and a second part being rotatable relative to each other, wherein the lightning current transfer unit is arranged to provide electrical contact between the first and second parts, the lightning current transfer unit comprising: a first current transfer portion comprising a first slider and configured to be electrically coupled to a first electrically conducting slideway of the first part of the wind turbine, the first slider being rotatable relative to the first slideway; a second current transfer portion configured to be electrically coupled to an electrically conducting portion of the second part of the wind turbine; a first main spring biasing the first slider towards the first slideway; wherein the first slider comprises: a primary contact biased towards the first slideway by the first main spring; a secondary contact arranged to move relative to the primary contact; and a secondary spring arranged between the first main spring and the secondary contact such that the secondary spring biases the primary contact away from the first slideway and biases the secondary contact towards the first slideway. ### Claim 2 (depends on 1) The lightning current transfer unit of claim 1, wherein the primary contact and the first slideway form a first current path to discharge electric charges from the first part, and the secondary contact and the first slideway form a second current path to discharge electric charges from the first part. ### Claim 3 (depends on 1) The lightning current transfer unit of claim 1, wherein the first main spring is a non-conductive elastically bendable strip. ### Claim 4 (depends on 3) The lightning current transfer unit of claim 3, wherein the first slider is hinged to the elastically bendable strip. ### Claim 5 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary spring is arranged between the primary contact and the secondary contact. ### Claim 6 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary spring is electrically conductive. ### Claim 7 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary spring is a coil spring. ### Claim 8 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary spring is a compression spring. ### Claim 9 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary spring is a torsion spring. ### Claim 10 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary spring provides a path for electrical current between the secondary contact and the primary contact. ### Claim 11 (depends on 1) The lightning current transfer unit of claim 1, further comprising an electrically insulating material surrounding the primary and secondary contacts, wherein the electrically insulating material is fixed relative to the primary contact. ### Claim 12 (depends on 11) The lightning current transfer unit of claim 11, wherein the electrically insulating material is formed from plastic. ### Claim 13 (depends on 12) The lightning current transfer unit of claim 12, wherein the electrically insulating material is configured to slide on the first slideway. ### Claim 14 (depends on 1) The lightning current transfer unit of claim 1, wherein the primary and secondary contacts are sliding contacts. ### Claim 15 (depends on 1) The lightning current transfer unit of claim 1, wherein the secondary contact is an alloy comprising copper and graphite. ### Claim 16 (depends on 1) The lightning current transfer unit of claim 1, wherein the electrically conducting portion of the second part comprises a second electrically conducting slideway, wherein the second current transfer portion comprises a second slider configured to be electrically coupled to the second electrically conducting slideway, the second slider being rotatable relative to the second slideway; the lightning current transfer unit further comprising a second main spring biasing the second slider towards the second slideway; wherein the second slider comprises: a second primary contact biased towards the second slideway by the second main spring; a second secondary contact arranged to move relative to the second primary contact; and a second secondary spring arranged between the second main spring and the second secondary contact such that the second secondary spring biases the second primary contact away from the second slideway and biases the second secondary contact towards the second slideway. ### Claim 17 (depends on 1) A wind turbine comprising a hub, a nacelle, a blade and a lightning current transfer unit according to claim 1, the lightning current transfer unit enabling electrical charges to be discharged from the blade to the nacelle. ### Claim 18 (depends on 17) The wind turbine of claim 17, wherein the first part of the wind turbine is the blade, and the blade is pitchably mounted on the hub and the first slideway is mounted on the blade. ### Claim 19 (depends on 17) The wind turbine of claim 17, wherein the first part of the wind turbine is the nacelle, and the first slideway is mounted on the nacelle. ### Claim 20 (depends on 17) The wind turbine of claim 17, wherein the first part of the wind turbine is the hub, and the first slideway is mounted on the hub. ### Claim 21 (depends on 17) The wind turbine of claim 17, wherein the first part of the wind turbine is the blade, and the blade is pitchably mounted on the hub and the first slideway is mounted on the blade; the second part of the wind turbine is the nacelle and the second slideway is mounted on the nacelle; and the first main spring and the second main spring are mounted on the hub and electrically insulated from the hub; wherein the first and second sliders are electrically connected in order to establish a current path from the blade to the nacelle thereby electrically bypassing the hub. ### Claim 22 (depends on 17) The wind turbine of claim 17, wherein the first part of the wind turbine is the blade, and the blade is pitchably mounted on the hub and the first slideway is mounted on the blade; the second part of the wind turbine is the nacelle and the second slideway is mounted on the hub and electrically insulated from the hub; the first slider is mounted on the hub by the first main spring and electrically insulated from the hub; and the second slider is mounted on the nacelle by the second main spring; wherein the first and second sliders are electrically connected in order to establish a current path from the blade to the nacelle thereby electrically bypassing the hub.