Current Sensor

• US 20020180417A1
• Filed: 04/01/2002
• Published: 12/05/2002
• Est. Priority Date: 04/02/2001
• Status: Active Grant

• Current Assignee: Edward Grellier Colby
• Original Assignee: Sentec Ltd. (Xylem, Inc.)
• Inventors: Storkey, Matthew Emmanuel Milton, Colby, Edward Grellier
• Granted Patent: US 6,734,661 B2
• Time in Patent Office: Days
• US Class Current: 324/117R
• CPC Class Codes: G01R 15/18 using inductive devices, e.g. transformers
• 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 22/00 Arrangements for measuring time integral of electric power or current, e.g. electricity meters

Abstract

A current sensor for measuring one or more currents supplied from a power source to a load, the sensor comprising:

(a) an inlet for connecting to the source;

(b) an outlet for connecting to the load;

(c) one or more conductive paths (94a, 94b, 94c; 250, 260) connected between the inlet and outlet for guiding the one or more currents through the sensor; and

(d) one or more sensors (70) for sensing one or more local magnetic fields generated around the one or more paths (94, 250, 260) by the current flowing therethrough, thereby providing a current measure indicative of the magnitude of the one or more currents.

The sensor is distinguished in that it comprises a plurality of elongate current coil elements (78) arranged in a substantially common plane and arranged to be substantially insensitive to remotely-generated magnetic fields and responsive to the one or more local magnetic fields for generating the current measure, the coil elements (78) being disposed in zones (75, 76, 77) having more than two effective centers (see FIG. 7) and exhibiting mutually opposing responses to the remote field.

The sensor is susceptible for use in a fiscal power meter.

Claims

1. A current sensor for measuring current flowing between a power source and a load, the sensor comprising:

an inlet for connection to the source;

an outlet for connection to the load;

conductor paths connected between the inlet and the outlet for guiding currents through the sensor; and

sensing means associated with each conductor path for sensing current flowing therethrough and for generating a corresponding current measure indicative of the magnitude of the current,

characterised in that each sensing means comprises an array of elongate conductive elements which are, firstly, so arranged as to be each mutually dissimilarly coupled to the local magnetic field generated, in use, by current flowing through the associated conductor path and, secondly, so interconnected as to render the sensing means substantially insensitive to magnetic fields generated remotely therefrom.

2. A sensor according to claim 1, wherein the elongate elements are spatially arranged to be substantially mutually parallel.

3. A sensor according to claim 2, wherein the conductor path associated with the elongate elements is a substantially linear elongate member disposed with its longitudinal axis substantially parallel to those of the elongate elements.

4. A sensor according to claim 1 wherein said conductor paths are integral with corresponding arrays of elongate conductive elements on an insulating substrate.

5. A sensor according to claim 4 wherein the insulating substrate is a printed circuit board and elongate elements are implemented as conductive tracks on the printed circuit board.

6. A sensor according to claim 5, wherein the elongate elements are interconnected on the circuit board substantially without the need to use vias.

7. A sensor according to claim 5, wherein the printed circuit board is a multi-layer board and the elongate elements are duplicated at a plurality of levels in the board with corresponding arrays coupled together.

8. A sensor according to claim 7, wherein the elongate elements are connected alternately between layers.

9. A sensor according to claim 1 wherein the conductor paths are magnetically coupled to their corresponding elongate elements substantially through one or more non-ferromagnetic gap regions.

10. A sensor according to claim 1 wherein the elongate elements are interconnected at regions remote from where they couple magnetically to their corresponding conductor paths.

11. A sensor according to claim 1 wherein a plurality of the conductor paths are disposed on opposing major faces of a plane encompassing the elongate elements.

12. An electrical energy meter comprising a sensor embodying the invention.