CURRENT SENSOR FOR MEASURING AN ALTERNATING CURRENT

• US 20180052191A1
• Filed: 03/09/2016
• Published: 02/22/2018
• Est. Priority Date: 03/10/2015
• Status: Active Grant

• Current Assignee: Socomec S A (Socomec Holding)
• Original Assignee: Socomec S A (Socomec Holding)
• Inventors: KERN, Christian
• Granted Patent: US 10,545,178 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils

Abstract

A current sensor provided with an electrical coil (5) made in the form of a printed circuit. Its closed contour is inscribed within a rectangle delimiting a through window (9) for passing a primary conductor (2). It comprises four rectilinear segments (TR) connected two by two by a circular sector (SC), delimited by an interior arc (10) and an exterior arc (11). It comprises, in its circular sectors (SC), additional turns (13), which extend from exterior arc (11) towards an intermediate arc (14) located between interior arc (10) and exterior arc (11). They are inserted between the main turns (12) in such a way that the spacing between two consecutive turns (12, 13) on the exterior arc (11) is equal to spacing (P) of the main turns (12) in rectilinear segments (TR) and that the average turns density is almost constant in electrical coil (5).

Claims

1-17. -17. (canceled)

18. A current sensor (1, 1′

) for measuring an alternating current, the sensor comprising;

at least one electrical coil (5, 50) made in a form of a printed circuit provided on at least one electronic board (4),

an electronic unit (6) for conditioning the signal of the electrical coil and an electrical terminal block (7),

the electrical coil (5, 50) having a closed contour inscribed within a polygon and delimiting in its center a through window (9) for an electrical conductor crossed by the alternating current to be measured, this conductor being called primary conductor (2),

the electrical coil (5, 50) comprising N rectilinear segments (TR) of width L and N circular sectors (SC) of a same width L delimited each by an interior arc (10) of interior radius Ri and an exterior arc (11) of exterior radius Re,

the rectilinear segments (TR) being connected two by two by a circular sector (SC),

the rectilinear segments (TR) being made of turns (12) separated from each other by a constant spacing P, and the circular sectors (SC) being made of turns (12) separated from each other on the interior arc (10) by a constant spacing equal to spacing P and on the exterior arc (11) by a constant spacing larger than spacing P,

wherein the electrical coil (5, 50) comprises additional turns (13, 15) in its circular sectors (SC) with a width (L1, L2) lower than the width (L) of the other turns, called main turns (12), and extending from the exterior arc (11) towards at least one intermediate arc (14, 16) located between the interior arc (10) and the exterior arc (11), the additional turns (13, 15) being inserted between the main turns (12) so that the spacing between two consecutive turns (12, 13, 15) on the exterior arc (11) is substantially equal to spacing P and that the average turns density is almost constant in the electrical coil (5, 50).

19. The current sensor according to claim 18, wherein the electrical coil (5) comprises, in its circular sectors (SC), first additional turns (13) with a width (L1) extending from the exterior arc (11) towards respectively a first intermediate arc (14) located between the interior arc (10) and the exterior arc (11).

20. The current sensor according to claim 18, wherein the electrical coil (50) comprises, in its circular sectors (SC), first additional turns (13) and second additional turns (15) with different respective widths (L1) and (L2) extending from the exterior arc (11) towards respectively a first intermediate arc (14) and a second intermediate arc (16) located between the interior arc (10) and the exterior arc (11).

21. The current sensor according to claim 18, wherein the electrical coil (5, 50) is made in the form of a printed circuit comprising at least a first conductive layer (17) and a second conductive layer (18), superimposed on each other, separated from each other by an insulating core (19) of a substrate (20) of the electronic board (4), and the first and second conductive layers (17, 18) are connected to each other by connecting holes (21) passing through the substrate (20) to form the turns (12, 13, 15) of the electrical coil (5, 50).

22. The current sensor according to claim 21, wherein the current sensor comprises a return conductor having a flat surface substantially equal to that of the electrical coil (5, 50) to cancel interference fields, the return conductor is made in the form of a printed circuit comprising at least a third conductive layer, superimposed on the electrical coil (5, 50) and separated from the electrical coil (5, 50) by an insulating layer of the substrate (20), and the return conductor is serially connected to the electrical coil (5, 50) by connecting holes passing through the substrate (20).

23. The current sensor according to claim 21, wherein the current sensor comprises two electrical coils (5, 50) made in the form of a printed circuit comprising at least four conductive layers (17, 18), the two electrical coils (5, 50) are identical, opposite to and superimposed on each other, separated from each other by a central insulating layer (22) of the substrate, and are serially connected by connecting holes (23) passing through the substrate (20).

24. The current sensor according to claim 18, wherein the current sensor comprises an electrical shield (24).

25. The current sensor according to claim 24, wherein the electrical shield (24) includes at least one upper exterior conductive layer (25) and one lower exterior conductive layer (26) covering the electrical coil (5, 50) and its return conductor, or the electrical coils (5, 50), and separated from the electrical coil(s) (5, 50) and/or from the return conductor by an additional insulating layer (27, 28) of the substrate (20).

26. The current sensor according to claim 24, wherein the electrical shield (24) comprises at least one lateral conductive layer (29) covering the edge of the substrate (20).

27. The current sensor according to claim 24, wherein the electrical shield (24) comprises a conductive housing (30) arranged around the electronic conditioning unit (6).

28. The current sensor according to claim 18, wherein the current sensor is a single-phase and comprises a through window (9) for a primary conductor (2), and the through window (9) is surrounded by at least one electrical coil (5, 50).

29. The current sensor according to claim 18, wherein the current sensor is polyphase and comprises N through windows (9) for N primary conductors (2), and each through window (9) is surrounded by at least one electrical coil (5, 50).

30. The current sensor according to claim 29, wherein the current sensor comprises one electronic board (4) provided with N through windows (9), and the corresponding electrical coils (5, 50) are arranged on the electronic board (4).

31. The current sensor according to claim 29, wherein the current sensor comprises at least two superimposed electronic boards (4a, 4b), comprising each N through windows (9), and the corresponding electrical coils (5, 50) are distributed alternately on the electronic boards (4a, 4b).

32. The current sensor according to claim 31, wherein electronic conditioning unit (6) associated to every electrical coil (5, 50) is arranged in the interval (I) located between the two electronic boards (4), forming intrinsically an electrical shield protecting the electronic conditioning units (6).

33. The current sensor according to claim 18, wherein the current sensor comprises a voltage measuring circuit (40) arranged for measuring the voltage applied to the primary conductor (2).

34. The current sensor according to claim 33, wherein the voltage measuring circuit (40) comprises at least one detection electrode (41) surrounding the through window (9) provided in the electrical coil (5, 50), and the detection electrode (41) is connected to a reference potential by a RC circuit (42, 43, 45) and is made of at least one lateral conductive layer (29) covering the edge of substrate (20) surrounding the through window (9).