US3701003A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current transformers with improved coaxial feed
Assignee: General Electric Co
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Filing: 1970-12-14
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Granted: 1972-10-24
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Expires: 1990-12-14
Abstract
Abstract Current transformer apparatus includes a toroidal core with a secondary winding thereabout. A metallic shield and coupling member surrounds the core and has a central longitudinal opening therein for the insertion of a coaxial current carrying conductor, the current of which is to be sensed. The shield and coupling member within the longitudinal opening is laterally slotted about the cylindrical surface thereof to allow direct and close electromagnetic coupling between the coaxial conductor and the core. In one embodiment, an inner shield is provided about the core and is slotted about the exterior periphery thereof. The impedance of the coaxial conductor and the transformer may be matched by a coaxial line extending through the opening in the shield and coupling member to optimize coupling. In another embodiment, a secondary winding terminating resistance is variable by inclusion in a removable coaxial resistance cartridge. Several transformers may be cascaded in tandem by passing the output of one coaxially into the input of another.
Inventors
- 👤 John M Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:53
CPC Classifications
H; H01; H01F; H01F38/00; H01F38/20; H01F38/22; H01F38/28; H01F38/30; H01F38/305
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
116 words
Current transformer apparatus comprising: a toroidal core adapted to surround a conductor, the current of which is to be sensed; a secondary winding about said core; coaxial means for electromagnetically coupling the current carrying conductor with said core and for shielding said core from spurious fields, said coupling and shielding means comprising a metallic shield enclosing said core and said winding and having a hollow cylindrical central section including an aperture for passing the conductor therethrough, said central section including a cylindrical wall which is slotted for effective electromagnetic coupling between said conductor and said core; means terminating said secondary winding with a predetermined resistance; and, means for extracting an electrical signal from said secondary winding.
Claim 2
Dependent Claim
116 words
Current transformer apparatus comprising: a toroidal core adapted to surround a conductor, the current of which is to be sensed; a secondary winding about said core; coaxial means for electromagnetically coupling the current carrying conductor with said core and for shielding said core from spurious fields, said coupling and shielding means comprising a metallic shield enclosing said core and said winding and having a hollow cylindrical central section including an aperture for passing the conductor therethrough, said central section including a cylindrical wall which is slotted for effective electromagnetic coupling between said conductor and said core; means terminating said secondary winding with a predetermined resistance; and, means for extracting an electrical signal from said secondary winding.
Claim 3
Dependent Claim
24 words
The transformer apparatus of claim 1 wherein said core is further surrounded by an inner shield which is slotted about the outer periphery thereof.
Claim 4
Dependent Claim
28 words
The transformer apparatus of claim 1 wherein the slotted shield is provided with oscillation-damping resistances to prevent resonance thereof within the operating frequency range of the transformer apparatus.
Claim 5
Dependent Claim
31 words
The transformer apparatus of claim 1 wherein the resistance terminating said secondary winding is contained in a removable cartridge that is mechanically integral with said means for extracting the electrical signal.
Claim 6
Dependent Claim
80 words
The transformer apparatus of claim 1 further comprising second current transformer apparatus of like structure to the first current transformer apparatus defined in claim 12, said second current transformer apparatus being serially connected with the first current transformer apparatus by fitting the aperture of the central section of the second current transformer apparatus over the signal extraction means of the first current transformer apparatus and Establishing electrical contact between the metallic shields of the first and second current transformer apparatus.
Claim 7
Dependent Claim
20 words
The transformer apparatus of claim 4 wherein said terminating resistance is within the range of approximately 0.1 to 50 ohms.
Claim 8
Dependent Claim
20 words
The transformer apparatus of claim 6 wherein said terminating resistance is in the form of a thin film coaxial resistor.
Claim 9
Dependent Claim
27 words
Transformer apparatus of claim 1 wherein said terminating resistance is preselectable to any desired value by the location thereof in a removable, replacable cartridge within said shield.
Claim 10
Dependent Claim
41 words
The apparatus of claim 8 wherein said removable cartridge contains a complete terminating circuit including reactive elements effective to provide means for causing the rise time characteristic of said transformer apparatus to be acceptable over a wide range of operating frequencies.
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) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |