US4947108A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric current sensing device
Assignee: Liaisons Electroniques Mecaniques LEM SA
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Filing: 1988-10-14
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Granted: 1990-08-07
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Expires: 2008-10-14
Abstract
Abstract A magnetic circuit is coupled with a primary conductor in which flows the current to be sensed. The magnetic circuit has at least one air gap with a magnetic field detector and is coupled with at least one measuring coil producing a magnetic flux for compensating the flux generated by the primary current. The necessary current in the measuring coil to achieve such flux compensation is a measure for the primary current. A magnetic shielding part is provided in the vicinity of the air gap inside the measuring coil.
Inventors
- 👤 Claude Gudel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:59
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/14; G01R15/20; G01R15/207
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
143 words
An electric current sensing device to be used for measuring a relatively high current flowing in a conductor and/or for producing an image thereof, comprising at least one magnetic circuit capable of being magnetically coupled with said primary conductor and having at least one air gap, at least one measuring coil coupled with said magnetic circuit, magnetic field detector means arranged inside said air gap, a control circuit and an associated current source having input terminals coupled with said magnetic field detector means, and having output terminals connected to a series connection of said measuring coil and current measuring and/or displaying means, said sensing device further comprising at least one magnetic shielding part arranged inside said measuring coil in the vicinity of said air gap, so as to surround substantially the whole cross section of the magnetic circuit portions forming said air gap.
Claim 2
Dependent Claim
143 words
An electric current sensing device to be used for measuring a relatively high current flowing in a conductor and/or for producing an image thereof, comprising at least one magnetic circuit capable of being magnetically coupled with said primary conductor and having at least one air gap, at least one measuring coil coupled with said magnetic circuit, magnetic field detector means arranged inside said air gap, a control circuit and an associated current source having input terminals coupled with said magnetic field detector means, and having output terminals connected to a series connection of said measuring coil and current measuring and/or displaying means, said sensing device further comprising at least one magnetic shielding part arranged inside said measuring coil in the vicinity of said air gap, so as to surround substantially the whole cross section of the magnetic circuit portions forming said air gap.
Claim 3
Dependent Claim
45 words
A device as claimed in claim 1, wherein said shielding part is insulated from at least one of said magnetic circuit portions forming the air gap, by a layer of an amagnetic material arranged between said shielding part and said portion of the magnetic circuit.
Claim 4
Dependent Claim
48 words
A device as claimed in claim 1, wherein said shielding part is formed by at least one sheet member of a very small thickness with respect to the dimensions of the cross section of the magnetic circuit portions forming the air gap, and is bent around these portions.
Claim 5
Dependent Claim
48 words
A device as claimed in claim 2, wherein said shielding part is formed by at least one sheet member of a very small thickness with respect to the dimensions of the cross section of the magnetic circuit portions forming the air gap, and is bent around these portions.
Claim 6
Dependent Claim
28 words
A device as claimed in claim 1, wherein said shielding part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
Claim 7
Dependent Claim
27 words
A device according to claim 2, wherein said shielding part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
Claim 8
Dependent Claim
27 words
A device according to claim 3, wherein said shielding part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
Claim 9
Dependent Claim
27 words
A device according to claim 4, wherein said shielding part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
References Cited (Backward Citations)
US2134589A
Cited
US2928048A
Cited
US3885212A
Cited
US4413230A
Cited
US4656418A
Cited
US4700131A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-06 | 1994-02-05 | 1994-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-06 | 1998-02-05 | 1998-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-06 | 2002-02-05 | 2002-08-07 | $7700.00 | Window Closed / Lapsed |