US4939448A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric current sensing device of the magnetic field compensationtype
Assignee: Liaisons Electroniques Mecaniques LEM SA
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Filing: 1988-10-14
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Granted: 1990-07-03
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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 an air gap with a magnetic field detector and is coupled with a measuring coil producing a magnetic flux for compensation 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 yoke part of high magnetic permeability is arranged in the vicinity of the air gap inside the measuring coil so as to form a magnetic shunt between the two magnetic circuit portions forming the air gap.
Inventors
- 👤 Claude Gudel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:13
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/14; G01R15/20; G01R15/207
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
146 words
An electric current sensing device to be used for measuring a relatively high current flowing in a primary 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 yoke part of high magnetic permeability arranged inside said measuring coil in the vicinity of said air gap, so as to constitute a magnetic shunt between the two magnetic circuit portions forming said air gap.
Claim 2
Dependent Claim
146 words
An electric current sensing device to be used for measuring a relatively high current flowing in a primary 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 yoke part of high magnetic permeability arranged inside said measuring coil in the vicinity of said air gap, so as to constitute a magnetic shunt between the two magnetic circuit portions forming said air gap.
Claim 3
Dependent Claim
45 words
A device as claimed in claim 1, wherein said yoke 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 yoke part and said portion of the magnetic circuit.
Claim 4
Dependent Claim
42 words
A deivce as claimed in claim 2, wherein said yoke 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.
Claim 5
Dependent Claim
27 words
A device according to claim 3, wherein said yoke part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
Claim 6
Dependent Claim
27 words
A device according to claim 2, wherein said yoke part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
Claim 7
Dependent Claim
42 words
A device as claimed in claim 1, wherein said yoke 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.
Claim 8
Dependent Claim
27 words
A device according to claim 6, wherein said yoke part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
Claim 9
Dependent Claim
28 words
A device as claimed in claim 1, wherein said yoke part extends over a length substantially equal to that of the measuring coil inside which it is arranged.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-02 | 1994-01-01 | 1994-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-02 | 1998-01-01 | 1998-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-02 | 2002-01-01 | 2002-07-03 | $7700.00 | Window Closed / Lapsed |