DC current sensor

• US 5,523,677 A
• Filed: 10/12/1994
• Issued: 06/04/1996
• Est. Priority Date: 10/12/1993
• Status: Expired due to Term

• Current Assignee: Sumitomo Seika Chemicals Company Limited
• Original Assignee: Sumitomo Seika Chemicals Company Limited
• Inventors: Kawakami, Makoto, Yamaguchi, Shigeru
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): KHOSRAVI, KOURO
• Application Number:
  US08/321,792
• Time in Patent Office: 601 Days
• Field of Search: 324/117 R, 324/127, 330/8, 307/416
• US Class Current: 324/117.00R
• CPC Class Codes: G01R 15/185 with compensation or feedback windings or interacting coils, e.g. 0-flux sensors using galvano-magnetic field sensors G01R15/20; conversion of DC into AC using transductors G01R19/20
• CPC Class Codes: G01R 19/20 using transductors , i.e. a magnetic core transducer the saturation of which is cyclically reversed by an AC source on the secondary side

Abstract

A DC current sensor has a detecting core with a plurality of detecting core members adapted to be divided in a circumferential direction for receiving the lead wire. A pair of annular exciting cores on one of said detecting core members formed of saturable magnetic material has a core intersection inter-connected perpendicularly to the circumferential direction of said detecting core members, and are disposed oppositely in spaced relation with said detecting core members to magnetically saturate a portion thereof by a magnetic flux produced substantially in the perpendicular direction against a magnetic flux in the circumferential direction, produced by the DC current flowing through said lead wire being detected, and to interrupt a magnetic path by the magnetic flux in the circumferential direction periodically. Exciting coils are wound around the exciting cores in negative-phase excitation.

Claims

1. A DC current sensor for detecting DC current in a lead wire without contacting the same comprising:

a detecting core including an annular saturable magnetic material, for receiving the lead wire,

said detecting core including a plurality of detecting core members adapted to be divided, at least, at one portion in a circumferential direction for disposing the lead wire therethrough, on one of said detecting core members, at least, a pair of annular exciting cores formed of saturable magnetic material having a core intersection inter-connected perpendicularly to the circumferential direction of said detecting core members, and being disposed oppositely in spaced relation with said detecting core members, so as to magnetically saturate a portion thereof by a magnetic flux produced substantially in the perpendicular direction against a magnetic flux in the circumferential direction, produced by the DC current flowing through said lead wire being detected, and to interrupt a magnetic path by the magnetic flux in the circumferential direction periodically, and further including exciting coils wound around the exciting cores, said respective exciting coils being connected for negative-phase excitation, and a detecting coil being wound around said exciting cores in a toroidal shape.

2. A DC current sensor in accordance with claim 1, wherein the exciting cores comprise adjacent pairs of rectangular cylindrical elements having adjoining wall portions disposed on opposite sides of said detecting core members.

3. A DC current sensor in accordance with claim 1, wherein each exciting coil is wound around adjoining wall portions of adjacent pair of exciting core members.

4. A DC current sensor in accordance with claim 1, wherein the detecting core member comprises, a pair of I-shaped detecting core members being connected by a portion of the exciting core in a body, and a U-shaped detecting core member formed in the body.

5. A DC current sensor in accordance with claim 4, wherein one end portion of the pair of I-shaped detecting core members is rotatably secured to one end portion of the U-shaped detecting core member in such a manner that, other end of the I-shaped detecting core members are operable to be freely opened and closed.

6. A DC current sensor in accordance with claim 1, wherein a balance volume of an exciting current is disposed between the pair of exciting coils.

7. A DC current sensor in accordance with claim 1, wherein the detecting core members and the exciting core members comprise permalloy.

8. A DC current sensor for detecting current in a lead wire without contacting the same comprising:

a detecting core including an annular saturable magnetic material for receiving the lead wire said detecting core including a plurality of detecting core members adapted to be divided, at least, at one portion in a circumferential direction for disposing said lead wire therethrough, on one of said detecting core members, at least, a pair of exciting cores formed of saturable magnetic material forming an annular shape having a core intersection inter-connected perpendicularly to the circumferential direction of said detecting core members, and being disposed oppositely in spaced relation with said detecting core members, so as to magnetically saturate a portion of said detecting core members by a magnetic flux produced substantially in the perpendicular direction against a magnetic flux in the circumferential direction produced by the DC current flowing through said lead wire being detected, and to interrupt a magnetic path by the magnetic flux in the circumferential direction periodically, and further including exciting coils wound around the exciting cores, said respective exciting coils being connected such that an exciting current having the relative phase difference of 90°

can be applied, the detecting coils being wound around said exciting cores in a toroidal shape, and said respective detecting coils being connected in series in a negative-phase.

9. A DC current sensor in accordance with claim 8, wherein exciting cores comprise two adjacent pairs of rectangular cylindrical members disposed on opposite sides of said detecting core members.

10. A DC current sensor in accordance with claim 8, wherein each exciting coil is wound around adjoining wall portions of the adjacent pairs of exciting core members.

11. A DC current sensor in accordance with claim 8, wherein the detecting core member comprises, a pair of I-shaped detecting core members connected by a portion of the exciting core in a body, and a U-shaped detecting core member formed in the body.

12. A DC current sensor in accordance with claim 11, wherein one end portion of the pair of I-shaped detecting core members is rotatably secured to one end portion of the U-shaped detecting core member in such a manner that, other end portions of the I-shaped detecting core members are operable to be freely opened and closed.

13. A DC current sensor in accordance with claim 8, wherein the 90°

phase circuit of an exciting current is disposed between the pair of exciting coils.

14. A DC current sensor in accordance with claim 8, wherein the detecting core members and the exciting core members comprise permalloy.