FR2896592A1 - Alternating current measuring device for conducting wire of electric circuit, has clamp with jaws having recesses to receive coil elements, handles integrated to jaws, and covers blocking elements in recesses and insulating elements - Google Patents

Abstract

The device has a clamp (1) formed of an insulating material and comprising fixed and mobile clamping jaws (2a, 2b) that comprise recesses receiving respective coil elements (9a, 9b), where one coil element is mounted in series with another coil element. A coil is formed around the coil elements, and two handles (5a, 5b) are integrated to the jaws and are articulated with respect to each other around a hinge. Two covers block the coil elements in the recesses, and electrically insulate the coil elements. An independent claim is also included for a method for fabricating a device for measuring alternating current in a conductor such as electric circuit, traversed by electric current.

Description

DEVICE FOR MEASURING THE ALTERNATING CURRENT OF A CONDUCTOR CROSSED BY A

ELECTRIC POWER

  The present invention relates to a device for measuring the alternating current of a conductor traversed by an electric current, such as an electric circuit for example, without requiring the opening of said circuit. In the field of devices for measuring the alternating currents of an electrical circuit for the measurement of electrical consumption for billing purposes for example, so-called magnetic core sensors are well known, this type of sensor having a high accuracy. Nevertheless, the open-circuit sensors using magnetic cores are less precise because of the interruptions of the magnetic circuit and increase the electrical risks by contact between the conductor traversed by the current to be measured and the sensor core, which is generally made of a conductive material. 'electricity.

  Moreover, Rogowski sensors are known that use the principle of Rogowski coils in order to measure the current flowing through a linear conductor, this type of sensor being essentially used for the measurement of strong currents. A Rogowski sensor operates on the principle of a transformer without a magnetic core and comprises a primary conductor such as a portion of an electrical circuit, and a secondary coil consisting of turns of a conductive wire, and placed around the crossed conductor by the current to be measured. The current flowing through the primary conductor generates a magnetic field at any point in space, according to the law of Biot and Savart, whose variations provide an electromotive force in the secondary coil. The integration of this electromotive force by means of electronic amplification and signal processing systems provides an image of the current flowing through the primary conductor. Such Rogowski sensors are described, for example, in German Patent DE 195 05 812 and in US Pat. No. 5,414,400.

  German patent DE 195 05 812 discloses a Rogowski sensor consisting of an annular support pierced at its center to allow passage of the conductor through which the current to be measured and a coil formed around said support. This type of Rogowski sensor has the disadvantage of requiring a large number of operations for its realization and being, therefore, expensive. In addition, this type of sensor requires the opening of the electrical circuit for its implementation on the latter, which is particularly restrictive. US Pat. No. 5,414,400 describes a sensor consisting of a support pierced at its center and a coil made on a printed circuit also pierced at its center to allow passage of the conductor through which the current to be measured. This type of sensor also has the disadvantage of requiring the opening of the electrical circuit for its implementation on the latter, which is particularly restrictive. In addition, printed circuit sensors are inexpensive but they have a reduced number of turns so that they produce an output signal of very low amplitude which makes them unsuitable for the detection of weak currents. In order to overcome these disadvantages, it has already been imagined cheaper sensors and able to be placed on an electrical circuit without opening the latter. This is the case, for example, of the US patent application US 2003/0137388 which describes a device for measuring an alternating current passing through a conductor of the Rogowski sensor type. The device consists of two coils of semi-annular turns made on printed circuits and articulated around a hinge to easily place the device on an electrical circuit without its opening.

  This type of device nevertheless has the disadvantage of not providing a precise measurement of low alternating currents because of the small surface area and the limited number of its turns. One of the aims of the invention is therefore to remedy all these drawbacks by providing a device for measuring an alternating current passing through a small conductor, simple in design, inexpensive, and providing a quick and easy installation. easy on an electrical circuit and a precise measurement of a current even weak.

  For this purpose, and in accordance with the invention, there is provided a device for measuring the alternating current of a conductor traversed by an electric current, such as an electric circuit for example, said device being of the type comprising one or more coils. said Rogowski consisting of one or more elements around which are formed windings comprising turns of a conductive wire; said device is remarkable in that it consists of a clamp obtained in an insulating material comprising two jaws, a so-called fixed jaw having a recess adapted to receive at least one said fixed winding element and a said mobile jaw having a recess adapted to receive at least one movable winding element connected in series with the fixed winding element, a winding being respectively formed around the fixed and movable winding elements, and two handles respectively integral with a jaw and articulated one by relative to the other around a hinge, said jaws having means for closing the recesses adapted to firstly block the winding elements in said recesses and secondly to electrically insulate said winding elements. It is clearly understood that, unlike the devices of the prior art, the blocking of the winding elements and their electrical insulation makes it possible to produce sensors of very small size that can be used in low-voltage electrical panels with high levels of overvoltage, for example category III 600V according to the IEC1010 standard, that is to say a surge of up to 6000 Volts. Other preferred but non-limiting aspects of the dipositif according to the invention are the following: the means for closing the recesses consist of electrically insulating resin in which the winding elements are embedded. - The closing means of the recesses consist of covers and respectively capping said recesses of the fixed jaw and the movable jaw, said covers cooperating with said jaws. - The device comprises an elastic means for moving the handles of the clamp from one another and keep the movable and fixed jaws in the closed position.

  Another object of the invention relates to a method for manufacturing a device for measuring the alternating current of a conductor through which an electric current flows, such as an electric circuit for example, said device being of the type comprising one or more coils. said Rogowski consisting of one or more elements and around which are formed windings comprising turns of a conductive wire; said method is remarkable in that it comprises at least the following steps of: - producing a plurality of so-called identical coil elements around which is formed respectively a winding, - series connection of the windings of said elements, and - positioning of said elements on the one hand in a so-called fixed jaw of a clamp comprising a recess adapted to receive at least two fixed winding elements connected in series, and on the other hand in a said mobile jaw of said clamp comprising a recess adapted to receive at less a movable winding element, said clamp comprising two handles respectively integral with a jaw and hinged relative to each other around a hinge. The realization of each said winding element is carried out according to the following steps of: - driving in rotation of a ring-shaped element of toroidal body around an axis coincident with the axis of the torus, -winding of a conducting wire around said toric body. On the other hand, the rotational drive of the O-ring segment member is synchronized with the rotational drive of the wire reel so as to obtain a determined distribution of the turns on the O-ring segment. According to an alternative embodiment of the method according to the invention, the realization of the winding elements is carried out according to the following steps of: - placing on a mandrel of several elements respectively consisting of a segment of a cylindrical body comprising a central hole and whose ends have cheeks respectively provided with a day, the mandrel through the holes of the elements to form a string of elements whose days are right of each other, - rotation of the mandrel around his axis and winding of a conductive wire around the cylindrical body of each element by translation of a reel parallel to the axis of the mandrel driven in rotation, said translation being synchronized with the rotation of the mandrel.

  Other advantages and features will emerge more clearly from the following description of several alternative embodiments, given by way of non-limiting examples, of the device for measuring an alternating current and of the method of manufacturing said device, with reference to FIGS. attached drawings in which: - Figure 1 is an exploded perspective view of a clamp constituting the device for measuring an alternating current according to the invention, - Figure 2 is a top view of the clamp shown on the Figure 1 in the open position, - Figure 3 is a top view of the clamp shown in Figure 1 in the closed position, - Figure 4 is a side view of a winding element adapted to be placed in the following clamp FIG. 5 is a view from above of a first variant embodiment of the measuring device according to the invention comprising winding elements such as represented in FIG. 4; FIG. a longitudinal sectional view of an alternative embodiment of a winding element of the measuring device according to the invention, - Figure 7 is a side view of the winding element shown in Figure 6, - the FIG. 8 is a view from above of a second variant of the measuring device according to the invention comprising winding elements as shown in FIGS. 6 and 7; FIG. 9 is a diagrammatic representation seen from the side of FIG. a device for manufacturing winding elements according to the invention as shown in FIG. 4; FIG. 10 is a schematic representation seen from above of the device for manufacturing winding elements represented in FIG. 9; FIG. 11 is a schematic representation seen from above of a device for manufacturing winding elements as represented in FIGS. 6 and 7.

  In this exemplary embodiment, a device for measuring the alternating current passing through a conductor wire of an electrical circuit that is particularly suitable for the under-counting of the consumption of an electric circuit will be described with a view to establishing detailed electricity consumption balance sheets. as is detailed in the French patent application FR 04 07011 of the applicant; However, the measuring device according to the invention may find many other applications without departing from the scope of the invention.

  Referring to Figure 1, the measuring device according to the invention comprises a clamp 1 comprising two jaws 2a and 2b articulated around a hinge 3. The clamp 1 comprises a first said fixed jaw 2a having a shape of angular segment of torus about 240 and having a recess 4a adapted to receive at least two so-called fixed winding elements connected in series as will be detailed later. Torus means a body whose volume is generated by the rotation of any closed line, such as a circle or a parallelogram for example, contained in a plane about an axis belonging to said plane and not passing through said closed line. Said clamp 1 comprises a second jaw said mobile 2b having a torus segment shape of about 120 and having a recess 4b adapted to receive at least one said mobile winding element connected in series with the fixed winding elements as will be detailed further. The fixed jaw 2a comprises a handle 5a comprising a recess 6a opening on the one hand at its proximal end in the recess 4a of the fixed jaw 2a and on the other hand at the distal end, known as the free end, of the handle Sa for allow the passage of electrical wires of the winding elements. The movable jaw 2b has a handle 5b articulated to the handle 5a of the fixed jaw 2a around the hinge 3 near its proximal end. Said hinge 3 consists of an elastically deformable blade. It is obvious that the hinge 3 may consist of any other means well known to those skilled in the art without departing from the scope of the invention. The clamp 1 further comprises an elastic means C to separate the handles 5a and 5b from each other and hold the fixed jaws 2a and movable 2b in the closed position as shown in Figure 3. This elastic means C consists of a compression spring whose free ends respectively cooperate with a lug 7a and 7b protruding from the internal flanks of the handles 5a and 5b respectively of the clamp 1.

  It goes without saying that the elastic means C may consist of any other equivalent means. Thus, by exerting pressure on the handles 5a, 5b the movable jaw 2b pivots relative to the fixed jaw 2a around the hinge 3 from a first so-called closed position where the fixed jaw 2a and mobile 2b are in contact with each other. other for forming a closed torus to a second so-called open position where the fixed jaws 2a and mobile 2b are separated by a space allowing the passage of a conductive wire of an electrical circuit, for example, crossed by an alternating current to measure. After the introduction of said conductive wire between the fixed jaws 2a and 2b mobile, with reference to Figure 2, the pressure on the handles Sa, 5b of the clamp is released so that the compression spring C, initially compressed during the opening the jaws 2a, 2b, apart the handles Sa, 5b to their initial position of closure, shown in Figure 3, where the fixed jaw 2a and movable 2b are in contact with each other to form a closed torus.

  Furthermore, the clip 1 comprises covers 8a and 8b which cap the recesses 4a, 4b of the fixed jaw 2a and the movable jaw 2b and their handles 5a and 5b respectively, said covers 8a, 8b cooperating with said wrists 5a, 5b and the jaws 2a, 2b by interlocking or by any other equivalent means, such as by thermo welding for example.

  According to a first variant embodiment of the measuring device according to the invention, with reference to FIGS. 4 and 5, each fixed and movable winding element 9a 9b consists of a segment of a toroidal body 10 having an angular segment of about 120 identical. In this particular embodiment, the toroidal body has a section in radial section in the form of a rectangle; nevertheless, said segment may have any form of closed line such as a circle or a parallelogram for example. The ring body segment 10 is adapted to receive a winding of turns 11 of a conductive wire, shown in dashed lines in FIGS. 4 and 5. Furthermore, the free ends of each fixed and movable winding element comprise a flange 12 said flanges 12 of the same element forming between them an angle of about 120 corresponding to the angular segment of said winding element 9a, 9b.

  The O-ring segment 10 of each winding element 9a, 9b has an annular recess 13 at each of its ends so that each fixed or movable winding element 9a, 9b has at its ends a greater number of turns per unit of length. to the number of turns per unit length of the central portion of said element 9a, 9b. By central part is meant that part of the segment of the toroidal body 10 between its two annular recesses 13. Referring to Figure 4, each fixed winding element 9a or mobile 9b comprises a rod 14, shown in dotted lines, extending normally from one of the flanges 12. This rod 14 allows to retain the winding element 9a or 9b during the realization of winding turns around the O-ring segment 10 as will be seen a little further. After completion of the winding, said rod 14 is removed by any appropriate means. The clamp 1 is adapted to receive two fixed winding elements 9a mounted in series positioned in the fixed jaw 2a so that they extend concentrically to the axis of the torus of the clamp 1 in the closed position. Said gripper 1 receives, moreover, a movable winding element 9b connected in series with the fixed winding elements 9a, the conductive wires passing at the level of the hinge 3. In the same manner as above, the movable winding element 9b is positioned in the movable jaw 2b of the clamp 1 so that it extends concentrically to the axis of the torus of the clamp 1 in the closed position. An electrically insulating resin is advantageously poured into the recesses 4a, 4b of the jaws 2a, 2b of the clamp 1 in such a way that the winding elements 9a, 9b are embedded in said resin. The latter provides locking functions of the winding elements 9a, 9b in the recesses 4a, 4b and electrical insulation of the assembly. Alternatively, the resin may be substituted by covers 8a, 8b blocking the winding elements 9a, 9b in the recesses 4a, 4b and providing electrical insulation of the assembly. Thus, the device according to the invention has no path for a possible electric arc in the air or on the surface of the jaws 2a, 2b of the clamp 1 so that, to obtain the clamp, it is appropriate to choose a dielectric withstand material adapted to overvoltages may appear in the conductor through which the current to be measured.

  In order to achieve the winding of turns 11 around the O-ring segment 10 of a winding element 9a or 9b, the latter is positioned, with reference to FIGS. 9 and 10, on a vertical bracket 15 carried by a horizontal base 16 and driven in rotation about a vertical axis 17 by an electric motor 18. Said bracket 15 comprises retaining means 19 of the winding element 9a, 9b. These retaining means 19 cooperate with the rod 14 of said winding element 9a, 9b in such a way that the axis of the toroidal segment of said winding element 9a, 9b coincides with the vertical axis of rotation of the bracket 15. The device for producing a winding further comprises a reel 20 consisting of a support 21 carrying a reel 22, a wire guide 23 and a counterweight 24, said support 21 being integral with the output shaft of an engine The electric motors 18 and 25 are driven by a control unit 26 in such a way as to synchronize the rotation of the wire guide 23 and the rotation of the bracket 15 in order to obtain a determined distribution of the winding turns on the housing segment. O-ring 10. According to a second alternative embodiment of the measuring device according to the invention, with reference to FIGS. 6 to 8, each winding element 9a, 913 consists of a cheek bobbin 26 comprising a cylindrical body segment 27 pierced at its center by a hole 28 and provided with cheeks 29 at its free ends. Said cheeks 29 consist of discs respectively having a V-shaped day 30, said day flaring from the cylindrical body segment 27 to the peripheral edge of the cheek 29. The day 30 of a cheek 29 s extends to the right of the day 30 of the second cheek 29 of the bobbin 26. Each bobbin 26 is adapted to receive a winding of turns 11 between its cheeks 29.

  Furthermore, with reference to FIG. 8, the clamp 1 is able to receive four fixed winding elements 9a consisting respectively of windings 26 mounted in series and positioned in the fixed jaw 2a so that the cheeks 29 of each winding 26 extend radially in said fixed jaw 2a. Said winders 26 are regularly spaced so that the cheeks 29 of a first bobbin 26 make an angle of about 60 with the cheeks 29 of an adjacent bobbin 26. Said gripper 1 receives, moreover, two movable winding elements 9b consisting of two windings 26 connected in series with the fixed winding elements 9a, the conductive wires passing at the level of the hinge 3. In the same way as previously, the windings 26 are positioned in the movable jaw 2b of the clamp 1 so that the cheeks 29 of each winding 26 extend radially in said movable jaw 2b. In addition, covers 8a, 8b and / or resin block the winding elements 9a, 9b in the recesses 4a, 413 and provide electrical insulation of the assembly. In order to carry out the winding of turns 11 of the windings, the latter are positioned, with reference to FIG. 11, on a generally cylindrical mandrel 31 passing through the holes 28 of the spools 26 to form a string of spools 26, the days 30 of which are at the right from each other, said windings being separated by spacers 32. The mandrel 31 and the coils 26 are rotated about their axis by an electric motor 33 or by any other equivalent means. The device for producing a winding comprises, moreover, a reel 20 consisting of a support 21 carrying a reel 22 and a wire guide 23, said support 21 being integral with a carriage 34 sliding on a rail 34 extending parallel to the mandrel 31. The carriage 34 is driven in translation along the rail 35 by any appropriate means, not shown in Figure 11. Finally, it is obvious that the examples that have just been given are only illustrations particular in no way limiting as to the fields of application of the invention.

Claims (16)

  1. A device for measuring the alternating current of a conductor through which an electric current flows, such as an electric circuit for example, said device being of the type comprising one or more Rogowski coils consisting of one or more elements (9a, 9b) around which are formed coils (11) comprising turns of a conductive wire, characterized in that it consists of a clamp (1) obtained in an insulating material comprising two jaws (2a, 2b), a said fixed jaw (2a) having a recess (4a) adapted to receive at least one so-called fixed winding element (9a) and a said mobile jaw (2b) having a recess (4b) adapted to receive at least one movable winding element (9b) connected in series with the fixed winding element (9a), a winding (11) being formed respectively around the fixed (9a) and movable (9b) winding elements, and two handles (5a, 5b) respectively integral of a jaw (2a, 2b) and articulated with respect to the other around a hinge (3), said jaws (2a, 2b) having means for closing the recesses (4a, 4b) adapted to firstly block the winding elements (9a, 9b) in said recesses (4a , 4b) and on the other hand to electrically insulate said winding elements (9a, 9b).   2. Measuring device according to claim 1 characterized in that the closing means of the recesses (4a, 4b) consist of resin, electrically insulating, in which are embedded the winding elements (9a, 9b).   3. Measuring device according to claim 1 characterized in that the closing means of the recesses (4a, 4b) consist of covers (8a, 8b) to cap said recesses (4a, 4b) of the fixed jaw (2a) and the movable jaw (2b), said covers (8a, 8b) cooperating with said jaws (2a, 2b)   4. Measuring device according to any one of claims 1 to 3 characterized in that it comprises an elastic means (6) to separate the handles (5a, 5b) of the clamp (1) from one another and holding the movable (2b) and fixed (2a) jaws in the closed position.   5. Measuring device according to any one of claims 1 to 4 characterized in that each fixed or movable element (9a, 9b) consists of a segment of a toric body (10) having an identical angular section, said segment of toroidal body (10) receiving a winding (11) of turns.   6. Measuring device according to claim 5 characterized in that the ends of each fixed or movable element (9a, 9b) comprise a flange (12), said flanges (12) forming between them an angle corresponding to the angular segment of said element ( 9a, 9b).   7. Measuring device according to any one of claims 5 or 6 characterized in that each ring body segment (10) has an annular recess (13) at each of its ends.   8. Measuring device according to any one of claims 5 to 7 characterized in that each fixed element (9a) and each movable element (91) are respectively positioned radially in the fixed jaw (2a) and the movable jaw (2b). ) of the clamp (1) so that the axis of each fixed element (9a) and movable (91) extends substantially in the same plane perpendicular to the axis of the hinge (3).   9. Measuring device according to any one of claims 1 to 4 characterized in that each fixed or movable element (9a, 9b) consists of a bobbin (26) comprising a cylindrical body segment (27), said body (27) receiving a winding (11) of turns.   10. Measuring device according to claim 9 characterized in that the ends of each bobbin comprise a cheek (29).   11. Measuring device according to claim 10 characterized in that each cheek (29) comprises a day (30) adapted to allow the passage of the conductive wire forming the turns of the coil (11).   12. Measuring device according to any one of the preceding claims characterized in that each fixed or movable element (9a, 9b) has at its ends a number of turns per unit length greater than the number of turns per unit length of the central portion of said element (919b).   13. A method of manufacturing a device for measuring the alternating current of a conductor traversed by an electric current, such as an electric circuit for example, said device being of the type comprising one or more Rogowski coils consisting of a or several elements (9a, 9b) and around which are formed windings (11) comprising turns of a conductive wire, characterized in that it comprises at least the following steps of: realization of several so-called winding elements (9a, 9b) around which is formed respectively a winding (11), series connection of the windings (1l) of said elements (9a, 9b), and positioning of said elements (9a, 9b) on the one hand in a said bit fixed (2a) of a clamp (1) having a recess (4a) adapted to receive at least two fixed winding elements (9a) connected in series, and secondly in a said mobile jaw (2b) of said clamp (1) having a recess (41) suitable for receiving r at least one movable winding element (9b), said clamp (1) comprising two handles (5a, 5b) respectively integral with a jaw (2a, 2b) and articulated with respect to each other around a hinge (3).   14. A method according to claim 13 characterized in that the realization of each said winding element (9a, 9b) is performed in the following steps of: driving in rotation of a member (9a, 9b) in the form of a segment of toric body about an axis coincident with the axis of the torus, winding a conductive wire around said toric body.   Method according to claim 14, characterized in that the rotational drive of the O-ring segment member (10) is synchronized with the rotational drive of the wire reel (20) so as to obtain determined distribution of the turns on the O-ring segment (10).   16. The method of claim 13 characterized in that the embodiment of the winding elements is performed according to the following steps of: establishment on a mandrel (31) of several elements (9a, 9b) respectively consisting of a segment of a cylindrical body (27) having a central hole (28) and whose ends have cheeks (29) respectively provided with a day (30), the mandrel (31) passing through the holes (28) of the elements (9a, 9b ) to form a string of elements (9a, 9b) whose days (30) are in line with each other, -rotation of the mandrel (31) about its axis and winding a conductive wire around the cylindrical body (27) each element (9a, 9b) by translation of a reel (20) parallel to the axis of the mandrel (31) driven in rotation, said translation being synchronized with the rotation of the mandrel (31).