# US 11,994,538 B2 · Current transducer with magnetic core on primary conductor bar > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,538 B2 - Document ID: US11994538B2 - Status: Granted - Kind: B2 - Application number: 17/442,453 - Filed: 2020-03-24 - Published: 2022-05-26 - Granted: 2024-05-28 - Earliest claimed: 2019-03-28 - Assignees: LEM International SA - Applicants: Lem International SA - Inventors: Arnaud Labbe; Gérard Lepine - Web page: https://patentgrep.com/patent/US11994538B2 ## CPC - G01R 15/183: {using transformers with a magnetic core} - G01R 15/202: {using Hall-effect devices (Hall elements in arrangements for measuring electrical power G01R21/08)} - G01R 19/0092: {Measuring current only} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract An open loop electrical current transducer including a primary conductor bar, for carrying a current to be measured, a magnetic core having a U shape formed by an end branch and lateral branches upstanding therefrom to free ends, a magnetic circuit gap formed between inner surfaces of the lateral branches at the free ends of the lateral branches, a magnetic field detector positioned in the magnetic circuit gap, and a housing surrounding the magnetic core and a section of the primary conductor bar extending through the magnetic core and beyond the magnetic core either side thereof. The primary conductor bar includes a central portion having a width (Wc) equal to the width of a magnetic field gap (Wg) such that the central portion is clamped between said lateral branches in an interference force fit. ## Claims ### Claim 1 An open loop electrical current transducer comprising a primary conductor bar for carrying a current to be measured, a magnetic core having a U shape formed by an end branch and lateral branches upstanding therefrom to free ends, a magnetic circuit gap formed between inner surfaces of the lateral branches at the free ends of the lateral branches, a magnetic field detector positioned in the magnetic circuit gap, and a housing surrounding the magnetic core and a section of the primary conductor bar extending through the magnetic core and beyond the magnetic core either side thereof, the primary conductor bar comprising a central portion having a width (Wc) equal to the width of a magnetic field gap (Wg) such that the central portion is clamped between said lateral branches in an interference force fit. ### Claim 2 (depends on 1) The current transducer according to claim 1, wherein the primary conductor bar central portion has a width (Wc) less that a width (W) of the section of primary conductor bar positioned either side of the magnetic core, the central portion formed by a pair of indents from opposing outer edges of the primary conductor bar, wherein each indent receives therein a lateral branch of the magnetic core in a close fit. ### Claim 3 (depends on 2) The current transducer according to claim 2, wherein a length (Li) of the indents in a direction of flow of the primary current, is essentially equal to a length (Lb) of the magnetic core. ### Claim 4 (depends on 2) The current transducer according to claim 2, wherein a width (Wb) of each lateral branch is equal to a width (Wi) of the indents +/−20%. ### Claim 5 (depends on 1) The current transducer according to claim 1, wherein the cross-section of a portion of primary conductor bar mounted within the housing has an essentially flat rectangular shape. ### Claim 6 (depends on 1) The current transducer according to claim 1, wherein the housing comprises a base comprising a magnetic field detector lodging portion inserted within the magnetic circuit gap and comprising a slot receiving the magnetic field detector therein such that the magnetic field detector is held within the magnetic circuit gap, separated from the lateral branches of the magnetic core by an insulating layer. ### Claim 7 (depends on 1) The current transducer according to claim 1, wherein a housing base comprises a magnetic field sensing unit lodging portion allowing translational insertion of the magnetic field sensing unit in the housing base, the housing further comprising a cover mounted over the magnetic field sensing unit lodging portion. ### Claim 8 (depends on 1) The current transducer according to claim 1, wherein the current transducer comprises a connector, the connector comprising a shroud integrally formed with the housing base and comprising terminals overmolded by the housing base and having connection portions connecting to a circuit board of the magnetic field sensing unit. ### Claim 9 (depends on 1) The current transducer according to claim 1, wherein the central portion has a rectangular cross-section and the magnetic core inner surface in close fit around the central portion also has a rectangular shape. ### Claim 10 (depends on 1) The current transducer according to claim 1, wherein the conductor primary conductor bar central portion comprises a base layer and one or more folded over conductor layers with a total width (Wc′) that equal to the width (Wg) of the airgap in the core. ### Claim 11 (depends on 10) The current transducer according to claim 10, wherein the folded over conductor layers are formed from a tongue integrally formed with and extending laterally from an edge of the primary conductor bar, the folding over direction being orthogonal to the direction of flow of the primary current through the airgap. ### Claim 12 An open loop electrical current transducer comprising a primary conductor bar for carrying a current to be measured, a magnetic core having a U shape formed by an end branch and lateral branches upstanding therefrom to free ends, a magnetic circuit gap formed between inner surfaces of the lateral branches at the free ends of the lateral branches, a magnetic field detector positioned in the magnetic circuit gap, and a housing surrounding the magnetic core and a section of the primary conductor bar extending through the magnetic core and beyond the magnetic core either side thereof, wherein a conductor primary conductor bar central portion comprises a base layer and one or more folded over conductor layers with a total width (Wc′) equal to the width (Wg) of the airgap in the core. ### Claim 13 (depends on 12) The current transducer of claim 12, wherein the primary conductor bar central portion has a width (Wc) equal to the width of the magnetic circuit gap (Wg) such that the central portion is clamped with a non-null force between said lateral branches in an interference force fit. ### Claim 14 (depends on 12) The current transducer according to claim 12, wherein the primary conductor bar central portion has a width (Wc) less that a width (W) of the section of primary conductor bar positioned either side of the magnetic core, the central portion formed by a pair of indents from opposing outer edges of the primary conductor bar, wherein each indent receives therein a lateral branch of the magnetic core in a close fit. ### Claim 15 (depends on 14) The current transducer according to claim 14, wherein a length (Li) of the indents in a direction of flow of the primary current, is essentially equal to a length (Lb) of the magnetic core. ### Claim 16 (depends on 14) The current transducer according to claim 14, wherein a width (Wb) of each lateral branch is equal to a width (Wi) of the indents +/−20%. ### Claim 17 (depends on 12) The current transducer according to claim 12, wherein the cross-section of a portion of primary conductor bar mounted within the housing has an essentially flat rectangular shape. ### Claim 18 (depends on 12) The current transducer according to claim 12, wherein the housing comprises a base comprising a magnetic field detector lodging portion inserted within the magnetic circuit gap and comprising a slot receiving the magnetic field detector therein such that the magnetic field detector is held within the magnetic circuit gap, separated from the lateral branches of the magnetic core by an insulating layer. ### Claim 19 (depends on 12) The current transducer according to claim 12, wherein a housing base comprises a magnetic field sensing unit lodging portion allowing translational insertion of the magnetic field sensing unit in the housing base, the housing further comprising a cover mounted over the magnetic field sensing unit lodging portion. ### Claim 20 The current transducer according to claim wherein 12, the current transducer comprises a connector, the connector comprising a shroud integrally formed with the housing base and comprising terminals overmolded by the housing base and having connection portions connecting to a circuit board of the magnetic field sensing unit. ### Claim 21 (depends on 12) The current transducer according to claim 12, wherein the central portion has a rectangular cross-section and the magnetic core inner surface in close fit around the central portion also has a rectangular shape. ### Claim 22 (depends on 12) The current transducer according to claim 12, wherein the folded over conductor layers are formed from a tongue integrally formed with and extending laterally from an edge of the primary conductor bar, the folding over direction being orthogonal to the direction of flow of the primary current through the airgap.