Apparatus for sensing current
View Patent ↗A current sensor assembly includes a sensor coil, an electrostatic shield coil, a core, a housing, and a magnetic shield. The sensing coil, electrostatic shield coil, core, housing, and magnetic shield can be of toroidal symmetry and arranged coaxially about a pair of primary current conductors. The conductors can be either asymmetric or symmetric with respect to the geometric center of the remaining sensor assembly. The core and a secondary winding make up a current sensor. The core is cylindrically shaped and fabricated of non-magnetic material. The secondary winding is wound over the cylindrical core to form a toroidally shaped winding. When assembled into the current sensor assembly, the core and windings are disposed around two single turn primary windings through which AC currents to be measured flow. Alternatively, the conductor can be flat and the sensor can be a solid state sensor that includes an electrostatic shield. The conductor can have a magnetic flux concentrator positioned about the conductor in the same region where the sensor is located.
1. A current sensor assembly comprising:
at least one conductor;
a current sensor spaced apart from said conductor, said current sensor comprising a substantially cylindrical core including at least one winding having a substantially toroidal shape; and
an electrostatic shield winding is sensing around winding to form an electrostatic shield coil;
an electrostatic shield surrounding said current sensor;
wherein said sensor surrounds said conductor.
2. A sensor assembly in accordance with claim 1 further comprising a housing and a magnetic shield, said housing positioned around said sensor and said magnetic shield positioned around said housing.
3. A sensor assembly in accordance with claim 2 wherein said sensor, said housing, said magnetic shield, and said electrostatic shield are of toroidal symmetry and arranged coaxially about said conductor.
4. A sensor assembly in accordance with claim 3 wherein said at least one conductor comprises two conductors disposed symmetrically with respect to the remaining sensor assembly.
5. A sensor assembly in accordance with claim 5 wherein said conductors are disposed concentrically with respect to the remaining toroidal assembly.
6. A sensor assembly in accordance with claim 3 wherein said at least one conductor comprises two conductors disposed asymmetrically with respect to the remaining sensor assembly.
7. A sensor assembly in accordance with claim 6 wherein said conductors are disposed side-by-side such that a center of a line joining centers of said conductors is approximately at a geometric center of the remaining toroidal assembly.
8. A sensor assembly in accordance with claim 2 wherein said core is an air core.
9. A current sensor assembly in accordance with claim 1 further comprising a registration unit for maintaining said conductor in registration with respect to said housing.
10. A sensor assembly in accordance with claim 9 wherein said housing includes at least one projection, said registration unit connected to said housing by said project.
11. A sensor assembly in accordance with claim 1 wherein said winding comprises a four layer winding.
12. A current sensor assembly comprising:
at least one conductor;
a solid state current sensor;
a sensing region; and
an electrostatic shield surrounding said one conductor;
wherein said electrostatic shield comprises a conducting shell that at least partially encloses said solid state sensor;
wherein said at least one conductor is disposed to form a generally U shaped structure;
wherein said solid state current sensor is disposed within said at least one conductor so as to form said sensing region.
13. A sensor assembly in accordance with claim 12 further comprising a magnetic flux concentrator as least partially surrounding said one conductor.
14. A sensor assembly in accordance with claim 13 wherein said magnetic flux concentrator comprises at least one of the group consisting of silicon steel, ferrite, and μ-metal.
15. A sensor assembly in accordance with claim 12 wherein said conducting shell comprises at least one of the group consisting of a flex circuit and an insulating material coated by a thin layer of copper.
16. A sensor assembly in accordance with claim 12 wherein said conductor has a rectangular cross section.
17. A sensor assembly in accordance with claim 12 wherein said conductor has a circular cross section.