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US 4,513,274 AGranted
Current transformer for measuring instruments
AssigneeLGZ Landis & Gyr Zug AG
InventorMathis Halder
Life of this patent
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Abstract
The current transformer for instruments for measuring electric currents includes a magnetic core that has two cores and an inductive current divider with three parallel current paths. The current dividers form, together with cores, two current transformer stages whose magnetic fluxes mutually cancel one another. In a current transformer for AC currents having a DC component, the ratio of the ohmic resistances of the individual current paths is in direct relation to their transformation ratio.
Claims6
A current transformer for use in electrical AC current measuring instruments,
- comprising in combination,
- first, second and third current circuits, each circuit including a first winding, and a second winding in series with said first winding, and each winding having respective predetermined numbers of turns,
- first and second cores,
- said first windings forming with said first core a first current transformer stage,
- said second windings forming with said second core a second current transformer stage,
- at least said first and third current circuits being connected in parallel,
- said first and second windings of said first circuit being wound on said first and second cores in a predetermined sense,
- said first winding of said third current circuit being wound on one of said cores in a sense opposite to said predetermined sense,
- said second winding of said third current circuit being wound on the other core in said opposite sense,
- a samll difference existing between the number of turns of said first and second windings of said third current circuit.
7 more elements
Dependencies are inferred from the claim text.