Current sensors
First Claim
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1. Apparatus for sensing the magnitude of a current flowing therethrough, comprising:
- a member having a plurality of current-carrying first element portions each having substantially the same resistance R1, and a second current-carrying element portion, coplanar with at least one of said first element portions, having a meander-line geometry and a second resistance R2 ;
each of said first element portion resistance R1 being less than the resistance R2 of said second element portion;
said second element portion being electrically connected in parallel with at least one of said first element portions;
said plurality of first element portions being arranged to each provide an induced current in the second element portion of magnitude and phase selected to substantially cancel one another; and
means associated with the second element portion for transforming the magnitude of current flowing through said second element portion to a sensor output current related to the total current flowing through said member by the ratio of the second resistance R2 and the first resistance R1.
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Abstract
A sensor for measuring large magnitudes of A.C. current utilizes a conductive member having a higher-resistance element parallelled by a pair of elements with lower, and substantially equal, resistance and so arranged as to cause cancellation of magnetic field effects upon the higher-resistance element due to a flow of current through the lower-resistance elements. Thermal-effect compensation of the higher-resistance element of the sensor is also disclosed. Active load termination of a current-sensing transformer, positioned about the higher-resistance element, is used.
72 Citations
15 Claims
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1. Apparatus for sensing the magnitude of a current flowing therethrough, comprising:
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a member having a plurality of current-carrying first element portions each having substantially the same resistance R1, and a second current-carrying element portion, coplanar with at least one of said first element portions, having a meander-line geometry and a second resistance R2 ;
each of said first element portion resistance R1 being less than the resistance R2 of said second element portion;
said second element portion being electrically connected in parallel with at least one of said first element portions;
said plurality of first element portions being arranged to each provide an induced current in the second element portion of magnitude and phase selected to substantially cancel one another; andmeans associated with the second element portion for transforming the magnitude of current flowing through said second element portion to a sensor output current related to the total current flowing through said member by the ratio of the second resistance R2 and the first resistance R1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification