AU2012245173B2

AU2012245173B2 - Sensor for measuring a current in an electric cable

Info

Publication number: AU2012245173B2
Application number: AU2012245173A
Authority: AU
Inventors: Michel Clemence; Erick Contini; Alain Moreux; Frederic Waterlot
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2011-11-10
Filing date: 2012-11-08
Publication date: 2014-07-03
Anticipated expiration: 2032-11-08
Also published as: FR2982673A1; AU2012245173A1; FR2982673B1; CN103197116A; CN103197116B; EP2592426B1; EP2592426A1; EP2592426C0

Abstract

SENSOR FOR MEASURING A CURRENT IN AN ELECTRIC CABLE Sensor (1) for measuring a current in an electric cable, comprising an electrical circuit (4) and a support (6) for the electrical circuit, with the electrical circuit being intended to surround the electric cable during said measurement by forming a loop, the support having an opening (12) and comprising two ends (14, 5 16) located on either side of the opening, the electrical circuit comprising a helical winding. The support is elastically deformable between a first position wherein it is at rest and the two ends are substantially face-to-face, and a second position wherein the two ends are separated from each other in relation to the first position, 10 with the support being sufficiently flexible and being formed in such a way that: - the support can be deformed from the first position towards the second position by pressing manually the opening of the support against the electric cable, in such a way as to pass the electric cable from the outside of the loop towards the inside of the loop, or from the inside of the loop towards the outside of the loop, 15 and - the support spontaneously passes back from the second position to the first position, once the electric cable has passed through the opening. Corresponding method for measuring a current in an electric cable. 20 Figure 1

Description

1 SENSOR FOR MEASURING A CURRENT IN AN ELECTRIC CABLE This invention relates to a sensor for measuring a current in an electric cable of the type comprising an electrical circuit and a support for the electrical circuit, the electrical circuit being intended to surround the electric cable during said measurement by forming a loop, with the support 5 having an opening interrupting the loop and the support comprising two ends located on either side of the opening, the electrical circuit comprising a helical winding. It is known to measure industrial currents, in particular at low or medium frequency, by arranging around the electric cable involved a 10 sensor of the aforementioned type. The electric cable act as the primary of a transformer and the electrical circuit of the sensor acts as the secondary of the transformer. By measuring characteristics of the induced voltage in the secondary of the transformer, it is possible to determine the intensity of the current circulating in the primary of the transformer, i.e. in the electric 15 cable. As such, the document EP-A-0 999 565 describes a device for measuring an electric current. This device comprises a transformer provided with a magnetic circuit in the form of an open coil able to be closed on a cable wherein the current to be measured circulates. This 20 device has the disadvantage that the closing of the coil after passing around the electric cable is carried out manually. When the access is narrow, the closing is difficult and can give rise to problems of safety. Document FR-A-1 478 330 describes a method for measuring industrial currents up to several hundreds of thousands of Hertz using the 25 magnetic field of the current to be measured. It comprises a single-layer low-pitch winding, of constantly straight section, for which the return conductor comes back directly towards the other end of the winding according to its axis, said winding forming a closed loop which surrounds the electric cable of which it is sought to measure the intensity. Such a 2 circuit is called a Rogowski coil. The latter is connected to an RC integrator circuit, which is in turn connected to a measuring device. The described method requires however a manual intervention on the winding in order to close the coil. This is not easy amongst a multitude of electric 5 cables and can give rise to problems of safety for the operator. Document US-A-7 253 603 describes a similar device. The problem of having to manually close the coil is resolved by implementing a "coil" that remains open on a permanent basis. This has the disadvantage that the electrical circuit is then more sensitive to the external electrical fields, 10 which can interfere with the measurement. A purpose of the invention is to provide a sensor for measuring a current in an electric cable of which the implementation is facilitated and secure and which provides a precise measurement of the current. To this effect, the invention has for purpose a sensor for measuring 15 a current in an electric cable of the aforementioned type, wherein the support is elastically deformable between: - a first position wherein it is at rest and the two ends are substantially face-to-face, and - a second position wherein the two ends are separated from each 20 other in relation to the first position, with the support being sufficiently flexible and being formed in such a way that: - the support can be deformed from the first position towards the second position by pressing manually the opening of the support against 25 the electric cable, in such a way as to pass the electric cable from the outside of the loop towards the inside of the loop, or from the inside of the loop towards the outside of the loop, and - the support spontaneously passes back from the second position to the first position, once the electric cable has passed through the 30 opening.

3 Advantageously, the support comprises two external guides to channel the electric cable towards the opening of the support and facilitate the deformation of the support from the first position towards the second position, when the electric cable and the opening of the support are 5 pressed against each other, the electric cable being located outside the loop. Preferably, the sensor also has a handle fixed to the support to press the opening of the support against the electric cable. An element, such as the electric cable, is said to be "inside" the loop when the latter surrounds the element. On the contrary, an element is 10 said to be "outside" the loop when the latter does not surround the element. According to particular embodiments, the sensor can include one or several of the following characteristics taken separately or according to all of the combinations that are technically possible: - the sensor further comprises a handle fixed to the support in order 15 to press the opening of the support against the electric cable; - the electrical circuit forms a Rogowski coil comprising an opening, the opening of the coil being located on either side of the opening of the support; - the support comprises a housing extending along said loop in 20 order to receive the helical winding of the electrical circuit; - the support comprises two internal guides to channel the electric cable towards the opening of the support and facilitate the deformation of the support from the first position towards the second position, when the electric cable and the opening of the support are pressed against each 25 other, the electric cable being located inside the loop; - the sensor comprises an element for maintaining in position the electric cable, with the element for maintaining in position being located inside the loop and comprising a housing to receive the electric cable in a predefined position in relation to the electrical circuit; 30 - the loop formed by the support extending substantially in a plane, the element for maintaining in position comprises two tubular portions 4 located substantially in said plane and each fixed to the support by two ends, with the tubular portions having, taken together, a lyre shape in said plane, with the bulging portion of the lyre constituting the housing of the element for maintaining in position; 5 - the sensor further comprises two magnets located in or on the ends of the support, with the two magnets placed in a relative position such that they exert an attraction on each other when the support is in the first position. The invention also relates to a method for measuring a current in an 10 electric cable, with the method implementing a sensor such as described hereinabove and comprising the following steps: - the electric cable being located outside the loop and the support being located in the first position, the support is manually pressed against the electric cable, the electric cable being in contact with the support on 15 either side of the opening of the support, in such a way as to deform the support from the first position towards the second position and to have the electric cable enter into the loop; and - with the electric cable being located inside the loop and the support having returned to the first position, one or several characteristics 20 of an induced current are measured in the electrical circuit by the current circulating in the electric cable, and a value of the current circulating in the electric cable is deduced using the measured characteristic or characteristics. According to a particular embodiment, the method can further 25 include the following step: the electric cable located inside the loop and the support located in the first position, the support is manually pressed against the electric cable, the electric cable being in contact with the support on either side of the opening of the support, in such a way as to deform the support from the first position towards the second position and 30 to have the electric cable exit the loop.

5 The invention shall be better understood when reading the following description provided solely by way of example and made in reference to the annexed drawings wherein: - Figure 1 shows a sensor according to the invention as a front view; 5 - Figure 2 shows a method according to the invention implementing the sensor shown in Figure 1; - Figure 3 shows a sensor according to a second embodiment of the invention, as a front view; - Figure 4 shows the sensor shown in Figure 3 as a profile view; 10 - Figure 5 shows a method implementing the sensor shown in Figure 3; - Figures 6, 7 and 8 show Rogowski coils constituting embodiments of the electrical circuit of the sensor shown in Figure 1 or of the sensor shown in Figure 3; 15 - Figure 9 shows an alternative of the sensor shown in figures 3 to 5. Figure 1 shows a sensor 1 comprising an electrical circuit 4 comprising a helical winding, a support for the electrical circuit 6 and a handle 8. The support 6 and the handle 8 can be of a single block, in a single material or two different materials. 20 The support 6 comprises a gutter 10 in the shape of a loop extending substantially according to a plane P. The loop is for example substantially symmetrical according to a plane A orthogonal to the plane P. The planes P and A are cut according to a direction D. The support 6 has an opening 12 interrupting the loop on plane A. 25 The support 6 therefore comprises two ends 14, 16 each located on either side of the plane A. The support 6 further comprises two external guides 18, 20 located on either side of the opening 12, two internal guides 22, 24 located on either side of the opening 12 and an element for maintaining in position 26 electric cable located inside the loop. 30 The support 6 comprises two branches 28, 30 starting from a median zone 32 of the support 6 located opposite the opening 12 and 6 extending substantially in the plane P according to two curved shapes, symmetrical to one another in relation to plane A, up to the ends 14, 16. Advantageously, the gutter 10 is of a general oblong shape, extending according to the direction D. According to a particular 5 embodiment, the gutter 10 is substantially circular. The support 6 is elastically deformable between a first position and a second position. In the first position, the support 6 is at rest and the two ends 14, 16 are substantially face-to-face. The loop is then almost closed. 10 Advantageously, the two ends 14, 16 are separated by less than 3 mm in the first position. For example, the two ends 14, 16 are in contact. In figure 2, the support 6 for the sensor 1 shown on the left is in the first position. In figure 2, the support 6 for the sensor 1 shown at the centre is in 15 the second position. In the second position, the two branches 28, 30 are separated from each other in relation to the first position. More precisely, in this example, the two ends 14, 16 of the support are separated from each other substantially in the plane P, according to a direction substantially orthogonal to the direction D. 20 The gutter 10 is made of flexible material, for example of plastic material. The gutter 10 comprises a housing adapted to receive the electrical circuit. In the example shown in Figure 1, the gutter 10 has a U-shaped section. The U opens according to a direction substantially orthogonal to 25 the plane P. According to a particular embodiment, the gutter 10 can be covered, i.e. it can comprise a cover closing the "U". The external guides 18, 20 are fixed on either side of the opening 12 on an external lateral wall 34 of the gutter. The external guides 18, 20 30 extend radially starting from the loop in the plane P.

7 The first external guide 18 has the shape of a triangular wedge as a front view. The second external guide 20 is advantageously in the extension of the handle 8. In other terms, the handle 8 is then fixed on the second 5 external guide 20 and the two have continuity in shape. The two external guides 18, 20 each have a guide surface 36, 38 intended to be in contact with the electric cable when the operator presses the support on the electric cable 40 located outside the loop. These two guide surfaces 36, 38 converge towards the opening 12 of the support 6. 10 Each internal guide 22, 24 comprises an oblique membrane extending substantially according to the plane P, inside the loop formed by the support. Each membrane comprises a guide edge 42, 44 inside the loop, extending from a zone located on one end 14, 16 of the support up to an intermediate zone of the support. The two guide edges 42, 44 15 converge towards the opening 12 of the support. The guide edges 42, 44 are intended to be in contact with the electric cable 40 when the operator presses the support 6 on the electric cable 40 located inside the loop. The element for maintaining in position 26 the electric cable is 20 located inside the loop formed by the support 6 and comprises a housing 46 to receive the electric cable 40 in a predefined position in relation to the electrical circuit 4. More precisely, the element for maintaining in position 26 comprises two tubular portions 48, 50 extending substantially in the plane P. 25 The tubular portions 48, 50 are fixed by one of their ends to the support 6, on the median portion 32 and by the other of their ends on one of the internal guides 22, 24. From a front view, each tubular portion 48, 50 comprises a rectilinear section located on the side of the median zone 32 of the support and an S-shaped section located on the side of the 30 internal guide 22, 24. Considered together, the two tubular portions 48, 50 have in the plane P a lyre shape.

8 The handle 8 is fixed on the end 16 of the support 6 where the electrical connection terminals A and B are located. According to an embodiment, the handle 8 extends substantially in the plane P. Advantageously, the handle extends according to the 5 direction D or according to a direction forming with the direction D a low angle a, for example less than or equal to 300, advantageously chosen equal to approximately 150. The handle 8 is comprised of a material that is more rigid than the support, in such a way that the operator can deform the support 6 by 10 acting on the handle 8 in the manner described hereinbelow. Furthermore, the handle 8 is electrically insulated. For example, the handle 8 has the aspect of a gutter with a U shaped section in continuity of material with the gutter 10 of the support. In the example shown in the figures 1 and 2, the handle 8 15 comprises a substantially rectilinear main portion 52 intended to be held by the operator and a terminal portion 54 integral with the support 6 and forming an obtuse angle with the main portion. The terminal portion 54 advantageously forms the second external guide 20. In the example shown in Figure 1, the electrical circuit 4 is in the 20 housing formed by the gutter 10. The electrical circuit 4 is located in or on the support 6. Advantageously, the electrical circuit 4 extends over the entire length of the loop, from the end 14 of the support to the other end 16. In reference to Figure 6, the electrical circuit 4 comprises a wound 25 conductor wire 56, an input wire 58 and an output wire 60. The input 58 and output 60 wires are located in the handle 8 and are connected respectively to an input terminal A and to an output terminal B of the wound conductor wire 56. Advantageously, the electrical circuit 4 constitutes a Rogowski coil 30 such as shown diagrammatically in figure 6. The input terminal A is located on one end 14 of the support. Starting from this input terminal A, 9 the wire 56 is wound regularly around a nucleus. The winding is helical and extends over the entire loop. The winding stops at a point C located on the other end 16 of the support. Starting from the point C, the wire 56 returns via the inside of the winding to an output terminal B. When the 5 support 6 is in the first position, the first coil and the last coil of the winding are facing each other on either side of the opening 12 of the support 6. The input A and output B terminals of the winding are located on the same end 14 of the support 6. The input 58 and output 60 wires of the electrical circuit 4 located in 10 the handle 8 are connected to a measuring device not shown. Figure 2 shows a method according to the invention implementing the sensor 1 shown in figure 1. This entails for example measuring a current i circulating in the electric cable 40 which is a part of a plurality of cables, for example cable 15 outlets in an electrical cabinet or a transformer. The three sensors 1 shown in Figure 2 show, from left to right, the same sensor 1 in three different positions that it occupies successively during an operation of setting the sensor in place on the electric cable 40. In a first step, using the handle 8 held in the hand, the sensor 1 is 20 displaced in such a way as to bring the support 6 in the vicinity of the electric cable 40 of which it is sought to measure the current i. This is shown by the sensor 1 shown on the left in figure 2. The support 6 is then in the first position. The two external guides 18, 20 of the sensor 1 are placed into 25 contact with the electric cable 40, then a force F1 is exerted on the handle 8 in order to press the support 6 against the electric cable 40. As a reaction, the electric cable 40 exerts forces on the external guides 18, 20, with these forces tending to separate the branches 28, 30 of the support 6 on the opening 12, i.e. provoke an elastic deformation of the support 6 30 towards the second position, shown by the sensor 1 shown at the centre in figure 2.

10 The electric cable 40, then located between the two ends 14, 16 of the support, enters into the loop formed by the support 6 and becomes immobilised in the housing 46 of the element for maintaining in position 26 with a lyre shape. The support 6 then returns spontaneously to its rest 5 position, i.e. the first position, shown by the sensor 1 shown on the right in figure 2. The support 6 and the electrical circuit 4 are then in a quasi-closed position around the electric cable 40. Using the measuring device, the difference in potential V in measured at the terminals A, B of the electrical 10 circuit 4 constituting a Rogowski coil, with this difference in potential V being induced by the electric current i circulating in the electric cable 40. According to a method known per se, the current i circulating in the electric cable 40 is deduced. Once the measurement is taken, the electric cable 40 is removed 15 from the loop by pushing on the handle 8 (force F2) in such a way as to press the electric cable 40 against the internal guides 22, 24 of the support 6. The electric cable 40 exits the housing 46 of the element for maintaining in position 26 in order to come into contact with the guide 20 surfaces 42, 44 of the internal guides 22, 24. The reaction of the electric cable 40 on the guide surfaces 42, 44 of the internal guides 22, 24 separates the ends 14, 16 of the support 6. The support 6 therefore passes from the first position to the second position, shown by the sensor 1 shown at the centre in figure 2. 25 The electric cable 40 then passes through the opening 12 of the support 6 and is located outside the loop. The support 6 returns to its first position shown by the sensor 1 shown on the left in figure 2. Thanks to the sensor 1 according to the invention, it is therefore possible to cause to enter and then cause to exit an electric cable 40 from 30 the loop formed by the support 6, without direct manual intervention on the support 6. The safety of the operator is, therefore, improved. The 11 measurement of the current i circulating in the electric cable 40 is precise because, when it is taken, the loop formed by the support 6 is quasi closed. The handle 8 has the advantage of allowing the operator to keep 5 his hand at a certain distance from the electric cable 40, on which the measurement is concerned, and from neighbouring electric cables 60, 61, 62, while offering the operator an electrical insulation when the handle 8 is manufactured from an insulating material, entirely or in part. Thanks to the handle 8, the electric cable 40 can be reached by the 10 sensor 1, even if it is located for the operator behind several electric cables 60, 61, 62 parallel to the electric cable 40. The sensor 1 can easily work its way between the electric cables 40, 60, 61, 62 by orientating the plane P (plane of the support 6) parallel to the direction of the electric cables 40, 60, 61, 62. Then, once the support 6 is behind the electric cable 15 40 in relation to the operator, a pivoting of the sensor 1 by approximately 900 around an axis materialised by the handle 8 places the sensor 1 in a suitable position in order to cause the electric cable 40 to enter into the loop formed by the support 6. The fixation of the handle 8 on one of the ends 16 of the support 6, 20 with a low angle a in relation to the direction D, makes it possible to cause to enter or exit the electric cable 40 respectively by pulling or by pushing on the handle 8, without having to impose a bending movement on the handle 8. When the electrical circuit 4 constitutes a Rogowski coil, the 25 measurement is a priori substantially independent of the location of the electric cable 40 inside the loop formed by the support 6 and independent of the presence of other cables through which currents are flowing located outside the loop. The gutter 10 of the support 6 makes it possible to protect the 30 electrical circuit 4.

12 The internal 22, 24 and external 18, 20 guides facilitate the passage of the electric cable 40 in the opening 12 of the support 6, from the inside of the loop towards the outside of the loop, and inversely. The element for maintaining in position 26 of the support 6 5 guarantees, thanks to its housing 46, that the electric cable 40 occupies a predetermined position in relation to the support 6, therefore in relation to the electrical circuit 4. As such, if the electrical circuit 4 is not a perfect Rogowski coil (for which the position has no effect on the measurement), the precision and the reproducibility of the measurement are improved. 10 The element for maintaining in position 26 also makes it possible to maintain the sensor 1 on the electric cable 40, which leaves the hands of the operator free during the measurement. The element for maintaining in position 26, having a lyre shape such as described hereinabove, creates a retaining force that contributes 15 in returning the support 6 to the first position when the two ends 14, 16 are separated from each other. Figures 3 to 5 show a second embodiment of the invention. A sensor 100 is shown as a front view in figure 3 and as a profile view in figure 4. The same references are retained for the elements that 20 are structurally identical to those of the first embodiment. The latter shall not be described in detail again. The sensor 100 differs primarily in that the handle 108 is fixed not on one end of the support, but in a region 32 that is substantially diametrically opposite the opening 12 of the support 6. 25 The sensor 100 comprises two external guides 118, 120 which are each independent of the handle 8, which is substantially rectilinear. According to a particular embodiment, the two external guides 118, 120 do not extend in the plane P of the loop formed by the support 6, but each form a given angle with this plane, with the two external guides 118, 30 120 located on either side of the plane P.

13 Due to the position of the handle 108, the electrical circuit 104 is adapted so that the input A and output B terminals are located on the median portion 32 of the support 6. In order to cause the electric cable 40 to enter the loop formed by 5 the support 6, the handle 108 is not pulled in order to press the support 6 against the electric cable 40 as in the first embodiment, but the handle 108 is pushed in order to exert this pressure, as shown in Figure 5. When the support 6 is pressed against the electric cable 40 in order to cause the latter to enter inside the loop formed by the support 6, the 10 support 6 is thus deformed in a particular manner. Indeed, the ends of the support 14, 16 do not separate from each other in the plane P, but substantially orthogonally to the plane P. As such the median zone 32 of the support 6, during the deformation from the first position towards the second position, is not bending as in the first embodiment, but is twisting. 15 Figures 7 and 8 show two possible forms for the electrical circuit 104, 204 in the second embodiment shown in Figures 3 to 5. These circuits 104, 204 are also Rogowski coils. The identical elements retain the same references and only the different elements shall be described. In figure 7, a first helical winding 156 leaves the input terminal A 20 and follows a branch 28 of the support 6 up to a point C1 located at the end of the branch 28. A second helical winding 158 leaves the input terminal A and follows the other branch 30 of the support 6 up to a point C2 located at the end of the branch 30 in question. A junction wire 160 connects the two points C1, C2 by passing through the inside of the two 25 windings 156, 158. The output terminal B is located on the junction wire 160 between the two windings 156, 158. The coils of the windings 156, 158 are oriented so that the induced electromotive forces in the two windings 156, 158 are added constructively to each other in order to form a voltage V between the terminals A and B. 30 In figure 8, a first helical winding 256 leaves the input terminal A and follows a branch 28 of the support 6 up to a point C1 located at the 14 end of the branch 28. A second helical winding 258 leaves the output terminal B and follows the other branch 30 of the support 6 up to a point C2 located at the end of the branch 30 in question. A wire 260 connects the two points C1, C2 by passing through the inside of the two windings 5 256, 258. The coils of the windings 256, 258 are oriented so that the induced electromotive forces in the two windings 256, 258 are added to one another in order to form a voltage V between the terminals A and B. Figure 9 shows a sensor 200 according to the invention, which is an alternative of the sensor 100 shown in figures 3 to 5. The same references 10 are used for similar elements, which will not be described again. The sensor 200 differs from the sensor 100 by the fact that it further comprises two magnets 202, 204 located in the ends 14, 16 of the support 6. The magnets 202, 204 are for example two permanent magnets. The magnets 202, 204 are placed is such a way that they attract 15 each other mutually when the support 6 is in the first position. The magnets 202, 204 as such exert an action tending to bring together the two ends 14, 16, particularly when they are not too far from one another, and to close the loop formed by the support 6 in the first position of the support 6. 20 Alternatively, the electrical circuit 4 is not defined in a gutter 10 arranged in the support 6, but is fixed via other means on the support 6.

Claims

1. A sensor for measuring a current in an electric cable, the sensor comprising an electrical circuit and a support for the electrical circuit, which is intended to surround the electric cable during said measuring by forming a loop, 5 the support having an opening interrupting the loop and the support comprising two ends located on either side of the opening, the electrical circuit comprising a helical winding, wherein the support is elastically deformable between: - a first position in which the support is at rest and the two ends of the support are substantially face-to-face, and 10 - a second position in which the two ends of the support are separated from each other in relation to the first position, the support being sufficiently flexible and being formed in such a way that: - the support can be deformed from the first position towards the second position by pressing manually the opening of the support against the 15 electric cable, in such a way as to cause the electric cable to pass from the outside of the loop towards the inside of the loop, or from the inside of the loop towards the outside of the loop, and - the support spontaneously returns from the second position to the first position, once the electric cable has passed through the opening, 20 the support comprising a first external guide and a second external guide to channel the electric cable towards the opening of the support and facilitate the deformation of the support from the first position towards the second position, when the electric cable and the opening of the support are pressed against each other, the electric cable being located outside the loop, wherein the second 25 external guide is in the extension of the handle.

2. A sensor according to claim 1, wherein the first external guide has the shape of a triangular wedge as a front view. 16

3. A sensor according to claim 1 or 2, wherein the electrical circuit forms a Rogowski coil comprising an opening, the opening of the coil being located on either side of the opening of the support.

4. A sensor according to any one of claims 1 to 3, wherein the support further 5 comprises a housing extending along said loop to receive the helical winding of the electrical circuit.

5. A sensor according to any one of claims 1 to 5, wherein the support comprises two internal guides in order to channel the electric cable towards the opening of the support and facilitate the deformation of the support from the first 10 position towards the second position, when the electric cable and the opening of the support are pressed against each other, the electric cable being located inside the loop.

6. A sensor according to any one of claims 1 to 6, further comprising an element for maintaining in position the electric cable located inside the loop and 15 comprising a housing to receive the electric cable in a predefined position in relation to the electrical circuit.

7. A sensor according to claim 7, wherein the loop formed by the support extends substantially in a plane, and the element for maintaining in position comprises two tubular portions located substantially in said plane and each fixed 20 to the support by two ends, with the tubular portions having, taken together, a lyre shape in said plane, with the bulging portion of the lyre constituting the housing of the element for maintaining in position.

8. A sensor according to any one of claims 1 to 8, c further comprising two magnets located in or on the ends of the support, with the two magnets being 25 placed in a relative position such that the two magnets exert an attraction on each other when the support is in the first position. 17

9. A method for measuring a current circulating in an electric cable, using a sensor as claimed in any one of claims 1 to 8, the method comprising the following steps: - locating the electric cable outside the loop and the support in the first 5 position of the support, and manually pressing the support against the electric cable, the electric cable being in contact with the support on either side of the opening of the support, in such a way as to deform the support from the first position towards the second position and to cause the electric cable to enter into the loop; and 10 - locating the electric cable inside the loop and returning the support to the first position, and measuring one or several characteristics of a current induced in the electrical circuit by the current circulating in the electric cable, and deciding a value of the current circulating in the electric cable using the characteristic or characteristics measured. 15

10. A method for measuring as claimed in claim 9, further comprising: locating the electric cable inside the loop and the support in the first position, manually pressing the support against the electric cable, the electric cable being in contact with the support on either side of the opening of the support, in such a way as to deform the support from the first position towards the second position and to 20 cause the electric cable to exit from the loop. SCHNEIDER ELECTRIC INDUSTRIES SAS WATERMARK PATENT AND TRADE MARKS ATTORNEYS P36768AU00