Patent US6231587B1 successfully refreshed from Google Patents.
US3708747A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical current transformer
Assignee: Alstom Savoisienne SA
•
Filing: 1971-10-22
•
Granted: 1973-01-02
•
Expires: 1991-10-22
Abstract
Abstract An optical current transformer in which two light beams coming from the same source successively pass through: (1) a first polarizer, a first material having a magnetic rotational power influenced by the electrical current to be measured and a first analyzer, to end up on a photoelectric detector; and (2) a second polarizer, a second material having a magnetic rotational power influenced by a measuring electrical current and a second analyzer, to end up on the same photoelectric detector. The measuring current is dependent on the detector for maintaining a constant flux on the latter. The angle between the polarization planes of the polarizers and the analyzers of each pair is 45*.
Inventors
- 👤 G Lesueur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:20
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/14; G01R15/24; G01R15/245; G01R15/246
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
216 words
An optical current transformer comprising: a. a first light path comprising in sequence: a first polarizer, a first magneto-optical element subject to a magnetic field produced by a current to be measured, a first analyzer whose polarization plane forms an angle of 45* with the polarization plane of said first polarizer, a photoelectric detector for generating a control signal dependent upon the intensity of light impinging thereon; b. a second light path comprising in sequence: a second polarizer, a second magneto-optical element subject to a magnetic field produced by a measuring current, a second analyzer whose polarization plane forms an angle of 45* with said second polarizer, and said photoelectric detector; c. means for generating first and second light beams along said first and second paths, respectively, so that said beams impinge upon said photoelectric detector; d. electronic means responsive to said control current for controlling said measuring current as a function of the intensity of light impinging upon said photodetector to maintain the intensity at a constant value equal to one half of the intensity which would impinge upon said photodetector if the polarization planes of said first and second light beams at the outputs of said first and second magneto-optical elements were merged, respectively, with the polarization planes of said first and second analyzers.
Claim 2
Dependent Claim
216 words
An optical current transformer comprising: a. a first light path comprising in sequence: a first polarizer, a first magneto-optical element subject to a magnetic field produced by a current to be measured, a first analyzer whose polarization plane forms an angle of 45* with the polarization plane of said first polarizer, a photoelectric detector for generating a control signal dependent upon the intensity of light impinging thereon; b. a second light path comprising in sequence: a second polarizer, a second magneto-optical element subject to a magnetic field produced by a measuring current, a second analyzer whose polarization plane forms an angle of 45* with said second polarizer, and said photoelectric detector; c. means for generating first and second light beams along said first and second paths, respectively, so that said beams impinge upon said photoelectric detector; d. electronic means responsive to said control current for controlling said measuring current as a function of the intensity of light impinging upon said photodetector to maintain the intensity at a constant value equal to one half of the intensity which would impinge upon said photodetector if the polarization planes of said first and second light beams at the outputs of said first and second magneto-optical elements were merged, respectively, with the polarization planes of said first and second analyzers.
Claim 3
Dependent Claim
28 words
An optical current transformer according to claim 1 wherein said first and second light beams have the same intensity at the outputs of said first and second polarizers.
Claim 4
Dependent Claim
52 words
An optical current transformer according to claim 1 wherein the planes of polarization of said first and second light beams are rotated through an angle of less than 5* by said first and second polarizers, respectively, and wherein the intensity of said first light beam at the output of said second polarizer.
Claim 5
Dependent Claim
35 words
An optical current transformer according to clAim 1 wherein said electronic means comprises subtractor circuit means responsive to said control signal and to a signal representative of said constant value for controlling said measuring current.
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) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |