# US 7,746,059 B2 · Current measurement apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,746,059 B2 - Document ID: US7746059B2 - Status: Granted - Kind: B2 - Application number: 10/599,843 - Filed: 2005-03-29 - Published: 2007-09-13 - Granted: 2010-06-29 - Earliest claimed: 2004-04-29 - Assignees: Lem Heme Limited - Inventors: Desmond Ebenezer; Albert Zwolinski - Web page: https://patentgrep.com/patent/US7746059B2 ## CPC - G01R 15/181: {using coils without a magnetic core, e.g. Rogowski coils} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract The current measurement apparatus comprises a Rogowski coil 20 comprising a wire or conductor which forms a coil 22 and returns through the coil 22 as a central conductor. The coil 22 and the central conductor are formed from a single conductor or wire and, therefore, no electrical join (for example, a solder join or crimp) is required at the end of the Rogowski coil. The wire 28 used to form the coil 22 and the central conductor 24 is insulated prior to forming the Rogowski coil. The insulated coating 30 provides better insulation between individual coils and also helps to provide a more even spacing between the coils. ## Claims ### Claim 1 Current measurement apparatus comprising a Rogowski coil wherein the Rogowski coil comprises a seamless conductive member, wherein the conductive member by itself is seamless, said single conductive member forms a coil and a central conductor extending through the coil wherein said conductive member forms single homogeneous wire and said homogeneous wire is insulated prior to forming the Rogowski coil. ### Claim 2 (depends on 1) Current measurement apparatus according to claim 1 in which the wire is insulated by insulating material. ### Claim 3 (depends on 2) Current measurement apparatus according to claim 2 in which the insulating material is resistant to physical damage. ### Claim 4 (depends on 2) Current measurement apparatus according to claim 2 in which the complete outer surface of the wire is coated with an insulating material. ### Claim 5 (depends on 4) Current measurement apparatus according to claim 4 in which the complete outer surface of the wire is coated with an insulating material which provides reinforced insulation. ### Claim 6 (depends on 2) Current measurement apparatus according to claim 2 in which the insulating material comprises a wrapping for the wire. ### Claim 7 (depends on 2) Current measurement apparatus according to claim 2 in which the insulating material is an extrusion. ### Claim 8 (depends on 1) Current measurement apparatus according to claim 1 in which the insulation coating is less than or equal to 0.125 mm. ### Claim 9 (depends on 1) Current measurement apparatus according to claim 1 in which the Rogowski coil is formed by providing a straight central conductor section and winding a coil around at least a part of the straight electrical conductor section. ### Claim 10 (depends on 1) Current measurement apparatus according to claim 1 in which the Rogowski coil comprises an inner sheath. ### Claim 11 (depends on 1) Current measurement apparatus according to claim 1 in which the wire comprises copper wire. ### Claim 12 (depends on 1) Current measurement apparatus according to claim 1 in which the Rogowski coil comprises an end wherein the end does not require an insulation cap. ### Claim 13 (depends on 1) Current measurement apparatus according to claim 1 in which the wire comprises a plurality of layers of insulating material. ### Claim 14 (depends on 1) Current measurement apparatus according to claim 1 in which the Rogowski coil comprises a first end and a second end. ### Claim 15 (depends on 14) Current measurement apparatus according to claim 14 in which, in use, the first end is arranged, in use, to locate adjacent to the second end. ### Claim 16 (depends on 14) Current measurement apparatus according to claim 14 in which, a first end member located on the first end is arranged, in use, to engage a second end member located on the second end. ### Claim 17 (depends on 1) Current measurement apparatus according to claim 1 in which a first end member located on one end of the Rogowski coil is arranged, in use, to cooperate with a second end member located on a second end of the Rogowski coil. ### Claim 18 (depends on 1) Current measurement apparatus according to claim 1 in which, in use, a first end of the Rogowski coil is arranged, in use, to cooperate with a second end member located on the second end of the Rogowski coil in order to form a contiguous loop. ### Claim 19 (depends on 1) Current measurement apparatus according to claim 1 in which a first end of the Rogowski coil is arranged to magnetically cooperate with a second end of the Rogowski coil. ### Claim 20 (depends on 16) Current measurement apparatus according to claim 16 in which the first end member comprises a female member and the second end member comprises a male member. ### Claim 21 (depends on 16) Current measurement apparatus according to claim 16 in which the first end member is arranged, in use, to be secured to the second end member solely by magnetic force. ### Claim 22 A method of forming current measurement apparatus comprising forming a Rogowski coil from a seamless conductive member, wherein the conductive member by itself is seamless; forming said seamless conductive member into a coil and a central conductor extending through the coil; insulating said seamless conductive member before forming said coil and central conductor. ### Claim 23 A Rogowski coil having a seamless conductive member, wherein said conductive member by itself is seamless, said seamless conductive member forms a coil and a central conductor extending through a center of the coil, and the seamless conductive element is insulated.