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WO1994028429A1 - Method and device for measuring the dynamic components of an electric current in the presence of a continuous component - Google Patents

Method and device for measuring the dynamic components of an electric current in the presence of a continuous component Download PDF

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Publication number
WO1994028429A1
WO1994028429A1 PCT/CH1994/000100 CH9400100W WO9428429A1 WO 1994028429 A1 WO1994028429 A1 WO 1994028429A1 CH 9400100 W CH9400100 W CH 9400100W WO 9428429 A1 WO9428429 A1 WO 9428429A1
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WO
WIPO (PCT)
Prior art keywords
current
transformer
housing
intensity
measured
Prior art date
Application number
PCT/CH1994/000100
Other languages
French (fr)
Inventor
François COSTA
Eric Laboure
Original Assignee
Liaisons Electroniques-Mecaniques Lem S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Liaisons Electroniques-Mecaniques Lem S.A. filed Critical Liaisons Electroniques-Mecaniques Lem S.A.
Priority to DE4493433T priority Critical patent/DE4493433T1/en
Publication of WO1994028429A1 publication Critical patent/WO1994028429A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
    • H01F27/422—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers
    • H01F27/427—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers for current transformers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core

Definitions

  • the present invention relates to a method for measuring dynamic components, at frequencies higher than megahertz, in an electric current (I (t)) flowing in a conductor, this method comprising a first step of transformation by magnetic coupling of the current to be measured ( I / t)) into a first induced current (I ⁇ (t)), and at least a second current transformation step by magnetic coupling in which the input current is the induced current from the preceding transformation step, the current induced from the last transformation step (Is (t)) being measured to obtain an image of the dynamic components of the current to be measured (I (t)).
  • Measuring methods which generally use a current transformer comprising a toroid at the center of which is placed the conductor traversed by the current to be measured and which is provided with a secondary winding with a large number of turns generating an output voltage which can be integrated to provide an image of the current to be measured.
  • the probes produced on this principle have good performance at low frequencies but are not suitable for high frequencies due to the number of turns being too high.
  • a main aim of the present invention is to remedy these drawbacks by proposing a method for measuring dynamic components of an electric current flowing in a conductor, which makes it possible to take account of the presence of a direct component and offers a very high bandwidth.
  • the method is characterized in that, in the first transformation step, the magnetic coupling is obtained by using a relatively high reluctance magnetic circuit to limit the incidence of a direct component of the current to be measured (I (t)) on the measurement of the dynamic components, and that, in each of the successive stages of transformation, the magnetic coupling is obtained by the use of a respective magnetic circuit having a significantly higher reluctance low to minimize the cutoff frequency, low measurement.
  • the magnetic coupling is obtained by the use of a magnetic circuit made of a material with high magnetic permeability, comprising at least one air gap.
  • the magnetic field in said air gap can be measured to obtain a measurement of the DC component of the current to be measured.
  • the measurement device comprises a set of at least two intensity transformers arranged in cascade comprising a first intensity transformer having the conductor traversed by the current to be measured as its primary, and a last current transformer having a secondary winding closed on a measurement impedance, each transformer following the first having for primary a conductor electrically shorting the secondary winding of the preceding transformer, and it is characterized, according to a form of embodiment, in that the magnetic circuit of the first intensity transformer (Tl) is made of a ferromagnetic material having a sufficiently low relative permeability to limit to a desired level the impact of a continuous component of the current to be measured on the measurement dynamic components, and that the magnetic circuits of the intensity transformers of rank greater than one (T2) are made of a ferromagnetic material having a significantly higher relative permeability.
  • the device is characterized in that the magnetic circuits of the intensity transformers are made of a ferromagnetic material having a relatively high permeability and that the magnetic circuit of the first intensity transformer (Tl) comprises at minus an air gap. It can then include means for measuring the magnetic field in said air gap.
  • FIG. 1 shows schematically the general arrangement of a device according to the invention
  • FIG. 2 is a sectional view of a measuring device implementing the method according to the invention.
  • FIG. 3 is a perspective view of a measuring device according to the invention
  • - Figure 4 is a sectional view of a housing arranged to contain the components of the measuring device according to the invention
  • FIG. 5 illustrates an example of internal mounting of a device according to the invention
  • FIG. 6 represents an experimental validation arrangement of a measurement device according to the invention.
  • FIG. 7 shows two current waveforms corresponding respectively to a measurement by inductive probe and to a measurement carried out with the device according to the invention.
  • a measuring device 1 comprises a first transformer T1 constituted for example by a magnetic circuit 4 of toroidal shape, having for primary a conductor 2 crossed by the current I (t) that one wishes to measure and for secondary a winding 5 comprising several turns, for example ten, and a second transformer T2 comprising a magnetic circuit 3, for example also of toroidal shape.
  • This second transformer T2 placed in a plane orthogonal to the plane of the first transformer Tl, has for primary a single conductor 9 passing through the center of the torus 3, connected on the one hand, to a first terminal of the secondary winding 5 of the first transformer Tl, and on the other hand, to the second terminal of said secondary winding 5 through a short circuit 6.
  • the second transformer T2 also has a secondary winding 7 wound around the toroid 3 and connected to a measurement impedance 8 traversed by an output current Is (t) which is the image of the current I (t) to be measured.
  • the ferrite constituting the magnetic circuit 4 of the first transformer Tl has a low relative permeability, in particular to avoid, in the targeted measurement range, saturation by the DC component of the current to be measured I (t), and too strong influence of this component on the low cut-off frequency, while the ferrite constituting the following toroid 3, or more generally all of the following tori in cascade, has a much higher permeability to ensure the lowest possible low cut-off frequency.
  • the current to be measured I (t) is applied to the primary 2 of the first intensity transformer Tl whose secondary 5, traversed by a current Il (t), is placed in short circuit through the primary 9, 6 of the second transformer of intensity T2.
  • the method according to the invention thus makes it possible to obtain:
  • a compact measuring device 20 comprises a first measuring module 35 containing in particular the two intensity transformers T1 , T2 and a second module 34 containing in particular the load resistor 8 and connection means 33 of the measurement device to external equipment (not shown), with reference to FIGS. 2 to 5.
  • the first module 35 comprises, with reference to the sectional view of FIG. 2, a first housing 25 designed to receive the first intensity transformer Tl and a second housing 26 designed to receive the second transformer T2 and a common mode filtering torus Tm.
  • these two housings 25, 26 are made in a non-magnetic conductive part 49 which provides the electromagnetic shielding of the measuring device.
  • the first intensity transformer Tl is placed around a ring 21 of non-magnetic material with a radius substantially equal to or less than the radius of the interior passage of the wound toroid 5 and of length less than the height of the housing 25 of so that a predetermined spacing e separates the free end of this ring 21 from the wall of the first housing 25 which is opposite.
  • This spacing equal for example to 1/10 mm, is provided to ensure that the ring 21, which is electrically connected to the shield 49, is not in electrical short circuit with this shield, which would have the effect of creating a loop surrounding the magnetic circuit 4.
  • the non-magnetic ring 21 makes it possible to eliminate the primary / secondary capacitance and to decrease the primary leakage inductance at high frequency (HF).
  • the conductor through which the current to be measured is placed in the housing 31 formed by the inner part of the non-magnetic ring.
  • the second housing 26 communicates with the first housing 25 through a narrow passage 27 sufficient to allow the passage of the conductors 9, 6 connected to the terminals of the secondary winding 5.
  • the aforementioned conductors pass through the central hole of the torus Tm of common mode filtering intended to reduce the circulation currents in the shielding part 49 of the measuring device.
  • the secondary current 5 of the first intensity transformer T1 constitutes the primary current of the second intensity transformer T2.
  • the first conductor 9 which constitutes the primary conductor of the second intensity transformer T2, is arranged coaxially and so as to produce a short circuit through the part 28 of the shielding piece 49 which surrounds the second intensity transformer T2 and which is connected electrically to the second conductor 6.
  • the measuring device 20 produced in practice is presented externally, with reference to FIG. 3, in the form of a parallelepipedic box consisting of a first box 35 and a second box 34 separated from the first by a copper plate 30 ; these two boxes having an identical section and being made of the same non-magnetic conductive material, for example Durai.
  • the first box 35 traversed by a cylindrical housing 31, intended to receive the conductor 2 which is the object of the current measurement, is closed by a flat cover 38 comprising a cylindrical hole 39 coinciding with the cylindrical housing 31 and four holes 37a, 37b, 37c, 37d placed at the four corners of said cover 38 and arranged to allow the screwing of this cover relative to the first housing 35.
  • the copper plate 30, having a surface greater than the common section of the first and second housings 35, 34 constitutes for the measuring device according to the invention a mass reference.
  • the second housing 34 provided in particular for receiving the measurement resistor 8, comprises two holes 61, 62 allowing the mechanical connection of the assembly constituted by the first housing 35, the copper plate 30 and the second housing 34, and a connector 33 of coaxial type comprising an external armature 57 electrically connected via the body of the second housing 34 to a first terminal of the measurement resistor 8, and an internal coaxial core 36 electrically connected to the second terminal of said resistance 8.
  • the voltage observed at the level of the connector 33 is an image of the current passing through the secondary winding of the intensity transformer T2.
  • the first and second housings 35, 34 are produced by machining homogeneous parallelepipedal blocks of the same material, for example Durai, in which recesses are made to receive the constituent elements of the measuring device according to the invention.
  • FIG. 4 represents a top view of the bare housings 35, 34 which constitute both the structures for receiving the components and an electromagnetic shielding.
  • the first housing 35 comprises a first annular housing 41 designed to receive the first intensity transformer Tl and having in its internal part the non-magnetic ring 21, a second housing 42, of substantially parallelepiped shape, intended to receive the torus Tm common mode filtering and a device for coaxial connection of the secondary winding of the first current transformer Tl to the primary conductor of the second current transformer T2, and a third housing 43, of cylindrical shape, intended to receive the second transformer of intensity T2.
  • the second housing 42 communicates with the first housing by a small hollowed-out passage of depth substantially less than the depth of the first and second housing and designed to allow the passage of the conductors connected to the secondary winding of the first current transformer Tl.
  • the third recess 43 communicates with the second housing 42 by a small circular hole 60 for receiving a threaded rod (not shown in Figure 4) acting between the coaxial conductor 1 * secondary winding of the first current transformer Tl and the primary of the second intensity transformer T2.
  • the first housing 35 also includes four threaded holes 37a, 37b, 37c, 37d designed to receive four screws (not shown) intended for fixing the cover 38 (cf. FIG. 3) relative to said first housing 35, and two threaded holes 47 , 48 designed to receive two screws (not shown) for fixing the second housing 34 and the copper plate 30 to the first housing 35.
  • the copper plate 30 comprises two fixing holes 63, 64 respectively opposite the holes 47, 48 formed in the first housing and holes 62, 61 made in the second housing 34, a main hole 45 provided for the passage of a threaded rod and an auxiliary hole provided for the passage of the output conductors of the secondary winding of the second current transformer T2 .
  • the second housing 34 comprises a housing 46 designed to receive the measurement resistor 8, a hole 44 made on its end wall and situated in the axis of the main hole 45 of the copper plate 30, and of the communication hole 60 between the second and third housings 42, 43, and holes 62, 61 respectively opposite the holes 63, 64 of the copper plate and the holes 47, 48 of the first housing 35, these holes 62, 61 being provided for receiving screw.
  • the first intensity transformer Tl is placed in the housing 41.
  • a first insulating element 51 for example a thin insulating film, is placed between the outer periphery of the first intensity transformer Tl and the wall 71 of the cylindrical housing 41
  • the secondary winding 5 is preferably made up of a small number of turns, for example ten, so as to limit the value of the parasitic inductances and capacitances. These turns are distributed uniformly over the toroidal magnetic circuit 4 and preferably produced by placing several elementary conductors, for example four, in parallel, in order to reduce the leakage inductance of the intensity transformer T1 and the resistance by skin effect.
  • the parallel conductors are combined to respectively constitute the conductor 9 intended to be connected to the conductive rod of a screw 56 and the conductor 6 intended to be connected to the coaxial shield constituted by a part of the first housing 35.
  • These two conductors 9, 6 pass into the internal orifice of the filtering torus Tm in common mode and then are connected respectively to a first washer 52 and to a second washer 54 separated from each other by an insulating washer 53, all of these three washers 52, 54, 53 being held in contact against a wall of the second housing 42 by a fixing system comprising the screw 56, a nut 55 located in the second housing 42 and at contact of the first washer 52, and the head 70 of the screw 56, located in the housing 46 of the second housing 34 and in contact with the copper plate 30.
  • the second intensity transformer T2 is placed in the third housing 43 of the first housing 35 and galvanically isolated from the internal walls of the third housing by an insulating film 51 '. Its secondary winding 7 is arranged in substantially the same way as the secondary winding of the first transformer T1: low number of turns, conductors placed in parallel and uniform distribution over the toroid.
  • the output conductors of the secondary winding 7 are passed through the auxiliary hole 65 of the copper plate 30 and terminate in the housing 46 of the second housing 34 to be connected to the terminals of the measurement resistor 8, the value of which can for example be chosen equal to 50 ohms.
  • a first terminal 72 of the measurement resistor 8 is electrically connected to the base 58 of the connector 33, while the second terminal 73 of the resistance 8 is electrically connected to the core 36 of said connector 33.
  • the latter is fixed to the side wall of the second housing 34 by a nut 74 and its base 58 is in electrical contact with the second housing 34 and the copper plate 30. It is thus possible to provide a mounting with an insulating washer 59 on the outside and a nut 74 made of material non-conductive, for example nylon. Many other arrangements of the output connector can be envisaged for delivering the voltage across the measurement resistor to the outside of the measurement device.
  • the magnetic circuit of the first intensity transformer Tl is, in the present example, made of ferrite material having a low relative permeability (for example, Ni-Z having a ⁇ R of approximately 300) and therefore not very sensitive to a direct component of the primary current.
  • the circuit of the second intensity transformer T2, and more generally of any other cascade transformers, is made of Zn-Mn ferrite material having a much higher permeability so that the cut-off frequency is as low as possible.
  • FIG. 1B shows such an alternative embodiment of the device in FIG. 1a, according to which the magnetic circuit 4 'of the first transformer T' ⁇ has an air gap 10.
  • a Hall cell 11 is placed in the air gap 10 and is connected, by means of conductors represented by line 12, to a measuring device 13 for measuring the DC component or components at low frequencies.
  • the presence of a current I (t) in the conductor 2 has the effect of generating a magnetic induction in the magnetic circuit 4 of the first transformer Tl. If the current I (t) varies temporally, the variation of the magnetic induction causes the creation of an induced current Il (t) in the secondary winding. This induced current flows through the conductors * 9 and 6 passing through the center of the filter core in common mode Tm and contributes to magnetize the magnetic circuit 3 of the second intensity transformer T2. A variable magnetic induction appears in the magnetic circuit 3 in response to the flow of current in the conductors 6 and 9, and contributes to the creation of an induced current i s (t) in the secondary winding 7 of the second transformer of intensity T2 which is closed on the measurement resistor 8.
  • the voltage observed at the terminals of the measurement resistor 8 is then a homothetic image of the current since the different physical quantities: current, magnetic induction, voltage are linked by linear relations.
  • the materials used for the magnetic circuits of the intensity transformers are chosen so that a quasi-perfect linearity is observed between the primary current and the secondary current.
  • the low relative permeability of the material used for the magnetic circuit of the first current transformer makes it possible to avoid saturation due to the existence of a continuous component of the current to be measured.
  • cascade current transformers, two in the example described makes it possible to use secondary windings with a small number of turns and consequently to significantly reduce the value of the parasitic components appearing in the equivalent assembly of the device.
  • the measuring device 20 has been used in an experimental validation setup 80 comprising a continuous power source 81, a filtering capacitor 82, a load 85, in particular an inductive load such as an electric motor. direct current, a freewheeling diode 84 mounted in antiparallel on the load 85, and a power transistor 86, for example a MOSFET transistor.
  • the drain of transistor 86 is connected to a terminal of the load 85 connected to the anode of the freewheeling diode 84, its gate is connected to a gate control circuit 83 and its source is connected to the ground of the assembly.
  • the source current I (t) is measured on the one hand by the measuring device 20 according to the invention, and on the other hand, by observation of the voltage drop across a calibrated inductance L present between the source and mass and very low value.
  • the voltage Vs (t) generated by the measuring device 20 is multiplied by a coefficient (1 /) to deliver a dynamic image I ⁇ (t) of the current to be measured I (t).
  • the voltage drop across the inductance L is observed by means of a probe 87, possibly attenuating if the peak voltage level justifies it, and is then integrated to deliver an image I R (t) of the current I (t ) to measure.
  • This measurement method which does not however offer any galvanic isolation, can provide, because of its simplicity of implementation, a reference measurement making it possible to validate the method according to the invention.
  • measuring devices having a low sensitivity to electromagnetic disturbances and high performance.
  • the following characteristics have been obtained for a measuring device actually produced:

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Abstract

The method comprises a first step for converting by magnetic coupling the current (I(t)) to be measured into a first induced current (I1(t)), and a second magnetic coupling current conversion step, in which the input current is the induced current from the first conversion step, and the induced current from the second conversion step (Is(t)) is applied to a measurement impedance (8) to provide an image of the dynamic component of the current (I(t)) to be measured.

Description

PROCEDE ET DISPOSITIF POUR LA MESURE DE COMPOSANTES METHOD AND DEVICE FOR MEASURING COMPONENTS
DYNAMIQUES D'UN COURANT ELECTRIQUE EN PRESENCEDYNAMICS OF AN ELECTRIC CURRENT IN THE PRESENCE
D'UNE COMPOSANTE CONTINUEOF A CONTINUOUS COMPONENT
La présente invention concerne un procédé pour la mesure de composantes dynamiques, à fréquences supérieures au Mégahertz, dans un courant électrique (I(t)) circulant dans un conducteur, ce procédé comprenant une première étape de transformation par couplage magnétique du courant à mesurer (I/t)) en un premier courant induit (Iι(t)), et au moins une deuxième étape de transformation de courant par couplage magnétique dans laquelle le courant d'entrée est le courant induit de 1'étape de transformation précédente, le courant induit de la dernière étape de transformation (Is (t) ) étant mesuré pour obtenir une image des composantes dynamiques du courant à mesurer (I(t)).The present invention relates to a method for measuring dynamic components, at frequencies higher than megahertz, in an electric current (I (t)) flowing in a conductor, this method comprising a first step of transformation by magnetic coupling of the current to be measured ( I / t)) into a first induced current (Iι (t)), and at least a second current transformation step by magnetic coupling in which the input current is the induced current from the preceding transformation step, the current induced from the last transformation step (Is (t)) being measured to obtain an image of the dynamic components of the current to be measured (I (t)).
Elle vise également un dispositif de mesure mettant en oeuvre ce procédé.It also relates to a measurement device implementing this method.
La mesure de courant représente actuellement un( maillon essentiel dans de nombreux dispositifs de régulation, automatismes industriels et en métrologie. On attend de plus en plus d'une mesure de courant qu'elle soit exploitable dans une large bande de fréquence et en présence ou non d'une composante continue. Ceci est dû au développement considérable des équipements d'électronique de puissance à haute fréquence, notamment des alimentations à découpage, où les bandes passantes des signaux à observer atteignent plusieurs centaines de MHz. En effet, lors des commutations, des oscillations créées par l'existence de capacités et d'inductances parasites peuvent atteindre des fréquences de plusieurs dizaines de MHz, justifiant une bande passante de plusieurs centaines de MHz pour observer correctement ces phénomènes. Par ailleurs, on observe des besoins 'grandissants en équipements de mesure destinés aux études de compatibilité électromagnétique (CEM) .Current measurement represents at present a (link essential in many control devices, automation and industrial metrology. It is expected that more and more a measure of current that it is operable in a wide frequency band and in the presence or not of a DC component. This is due to the considerable development of high frequency power electronic equipment, in particular switching power supplies, where the bandwidths of the signals to be observed reach several hundreds of MHz. , oscillations created by the existence of parasitic capacitances and inductances can reach frequencies of several tens of MHz, justifying a bandwidth of several hundreds of MHz to correctly observe these phenomena. In addition, there is an increasing need for measurement equipment intended for electromagnetic compatibility (EMC) studies.
On connaît des procédés de mesure qui mettent généralement en oeuvre un transformateur de courant comprenant un tore au centre duquel est placé le conducteur parcouru par le courant à mesurer et qui est doté d'un enroulement secondaire à grand nombre de spires générant une tension de sortie qui peut être intégrée pour fournir une image du courant à mesurer. Les sondes réalisées sur ce principe présentent de bonnes performances à basse fréquence mais ne sont pas appropriées aux hautes fréquences du fait d'un nombre de spires trop élevé.Measuring methods are known which generally use a current transformer comprising a toroid at the center of which is placed the conductor traversed by the current to be measured and which is provided with a secondary winding with a large number of turns generating an output voltage which can be integrated to provide an image of the current to be measured. The probes produced on this principle have good performance at low frequencies but are not suitable for high frequencies due to the number of turns being too high.
On connaît également des procédés de mesure de courant par effet Hall performants à basse fréquence mais présentant une bande passante insuffisante limitée par les performances de l'asservissement interne de courant mis en oeuvre. Il existe aussi des sondes de mesure combinant une sonde à effet Hall et un transformateur de courant, qui présentent une bande passante du continu jusqu'à plusieurs dizaines de MHz mais sont très sensibles à l'environnement électromagnétique.There are also known efficient Hall effect current measurement methods at low frequency but having an insufficient bandwidth limited by the performance of the internal current control implemented. There are also measurement probes combining a Hall effect probe and a current transformer, which have a continuous bandwidth up to several tens of MHz but are very sensitive to the electromagnetic environment.
Il existe également un procédé de mesure mettant en oeuvre une fibre optique comme élément sensible au courant. Ce procédé, basé sur l'effet Faraday, permet la mesure de courants très élevés dans d'excellentes conditions d'isolation, avec une grande bande passante et une bonne précision et est actuellement utilisé dans des applications à tension et courant élevés.There is also a measurement method using an optical fiber as a current-sensitive element. This method, based on the Faraday effect, allows the measurement of very high currents under excellent isolation conditions, with a large bandwidth and good precision and is currently used in high voltage and current applications.
On connaît aussi un procédé consistant à mesurer la tension aux bornes d'une résistance traversée par le courant à mesurer dans un ' dispositif d'électronique. La bande passante correspondant à ce procédé est uniquement limitée par l'effet de peau dans 1*élément résistif. Mais ce procédé présente l'inconvénient de ne pas assurer d'isolation entre la partie puissance et le dispositif de mesure. Un but principal de la présente invention est de remédier à ces inconvénients en proposant un procédé permettant de mesurer des composantes dynamiques d'un courant électrique circulant dans un conducteur, qui permette de tenir compte de la présence d'une composante continue et offre une très grande bande passante.Also known is a method comprising measuring the voltage across a resistor through which the current to be measured in an 'electronic device. The bandwidth corresponding to this process is only limited by the skin effect in the resistive element. However, this method has the drawback of not ensuring isolation between the power part and the measuring device. A main aim of the present invention is to remedy these drawbacks by proposing a method for measuring dynamic components of an electric current flowing in a conductor, which makes it possible to take account of the presence of a direct component and offers a very high bandwidth.
Suivant l'invention, le procédé est caractérisé en ce que, dans la première étape de transformation, le couplage magnétique est obtenu par mise en oeuvre d'un circuit magnétique à réluctance relativement élevée pour limiter à un niveau voulu l'incidence d'une composante continue du courant à mesurer (I(t)) sur la mesure des composantes dynamiques, et que, dans chacune des étapes successives de transformation, le couplage magnétique est obtenu par mise en oeuvre d'un circuit magnétique respectif présentant une réluctance sensiblement plus faible pour minimiser la fréquence de coupure, basse de la mesure.According to the invention, the method is characterized in that, in the first transformation step, the magnetic coupling is obtained by using a relatively high reluctance magnetic circuit to limit the incidence of a direct component of the current to be measured (I (t)) on the measurement of the dynamic components, and that, in each of the successive stages of transformation, the magnetic coupling is obtained by the use of a respective magnetic circuit having a significantly higher reluctance low to minimize the cutoff frequency, low measurement.
Selon une forme de mise en oeuvre de ce procédé, dans la première étape de transformation, le couplage magnétique est obtenu par la mise en oeuvre d'un circuit magnétique en un matériau à perméabilité magnétique élevée, comportant au moins un entrefer. Dans ce cas, l'on peut mesurer le champ magnétique dans ledit entrefer pour obtenir une mesure de la composante continue du courant à mesurer.According to one form of implementation of this method, in the first transformation step, the magnetic coupling is obtained by the use of a magnetic circuit made of a material with high magnetic permeability, comprising at least one air gap. In this case, the magnetic field in said air gap can be measured to obtain a measurement of the DC component of the current to be measured.
Le dispositif de mesure, mettant en oeuvre le procédé selon l'invention, comprend un ensemble d'au moins deux transformateurs d'intensité disposés en cascade comportant un premier transformateur d'intensité ayant pour primaire le conducteur parcouru par le courant à mesurer, et un dernier transformateur d'intensité possédant un enroulement secondaire fermé sur une impédance de mesure, chaque transformateur suivant le premier ayant pour primaire un conducteur court-circuitant électriquement l'enroulement secondaire du transformateur précédent, et il est caractérisé, selon une forme de réalisation, en ce que le circuit magnétique du premier transformateur d'intensité (Tl) est réalisé en un matériau ferromagnétique présentant une perméabilité relative suffisamment faible pour limiter à un niveau voulu l'incidence d'une composante continue du courant à mesurer sur la mesure des composantes dynamiques, et que les circuits magnétiques des transformateurs d'intensité de rang supérieur à un (T2) sont réalisés en un matériau ferromagnétique présentant une perméabilité relative sensiblement plus élevée.The measurement device, implementing the method according to the invention, comprises a set of at least two intensity transformers arranged in cascade comprising a first intensity transformer having the conductor traversed by the current to be measured as its primary, and a last current transformer having a secondary winding closed on a measurement impedance, each transformer following the first having for primary a conductor electrically shorting the secondary winding of the preceding transformer, and it is characterized, according to a form of embodiment, in that the magnetic circuit of the first intensity transformer (Tl) is made of a ferromagnetic material having a sufficiently low relative permeability to limit to a desired level the impact of a continuous component of the current to be measured on the measurement dynamic components, and that the magnetic circuits of the intensity transformers of rank greater than one (T2) are made of a ferromagnetic material having a significantly higher relative permeability.
Suivant une autre forme d'exécution, le dispositif est caractérisé en ce que les circuits magnétiques des transformateurs d'intensité sont réalisés en un matériau ferromagnétique présentant une perméabilité relativement élevée et que le circuit magnétique du premier transformateur d'intensité (Tl) comporte au moins un entrefer. Il peut alors •comporter des moyens pour mesurer le champ magnétique dans ledit entrefer.According to another embodiment, the device is characterized in that the magnetic circuits of the intensity transformers are made of a ferromagnetic material having a relatively high permeability and that the magnetic circuit of the first intensity transformer (Tl) comprises at minus an air gap. It can then include means for measuring the magnetic field in said air gap.
D'autres particularités et avantages de l'invention apparaîtront dans la description donnée ci-après d'exemples de réalisation illustrés aux dessins annexés dans lesquels:Other features and advantages of the invention will appear in the description given below of exemplary embodiments illustrated in the appended drawings in which:
- la figure la montre schématiquement l'agencement général d'un dispositif selon l'invention;- The figure shows schematically the general arrangement of a device according to the invention;
- la fig. lb montre, également schématiquement, une variante d'exécution du dispositif de la figure la;- fig. lb shows, also schematically, an alternative embodiment of the device of Figure la;
- la figure 2 est une vue en coupe d'un dispositif de mesure mettant en oeuvre le procédé selon l'invention;- Figure 2 is a sectional view of a measuring device implementing the method according to the invention;
- la figure 3 est une vue en perspective d'un dispositif de mesure selon l'invention; - la figure 4 est une vue en coupe d'un boîtier agencé pour contenir les composants du dispositif de mesure selon l'invention;- Figure 3 is a perspective view of a measuring device according to the invention; - Figure 4 is a sectional view of a housing arranged to contain the components of the measuring device according to the invention;
- la figure 5 illustre un exemple de montage interne d'un dispositif selon l'invention;- Figure 5 illustrates an example of internal mounting of a device according to the invention;
la figure 6 représente un montage de validation expérimental d'un dispositif de mesure selon l'invention; etFIG. 6 represents an experimental validation arrangement of a measurement device according to the invention; and
la figure 7 montre deux formes d'onde de courant correspondant respectivement à une mesure par sonde induetive et à une mesure effectuée avec le dispositif selon l'invention.FIG. 7 shows two current waveforms corresponding respectively to a measurement by inductive probe and to a measurement carried out with the device according to the invention.
On va maintenant expliquer le procédé de mesure selon l'invention en décrivant un mode particulier de réalisation d'un dispositif selon l'invention, en référence aux figures la à 5.We will now explain the measurement method according to the invention by describing a particular embodiment of a device according to the invention, with reference to Figures la to 5.
Le procédé utilisé dans 1'invention consiste en la mise en cascade d'au moins deux transformateurs d'intensité dont les circuits magnétiques sont constitués de ferrites de performances différentes. Ainsi, en référence à la figure la, un dispositif de mesure 1 selon 1*invention comprend un premier transformateur Tl constitué par exemple d'un circuit magnétique 4 de forme torique, ayant pour primaire un conducteur 2 traversé par le courant I (t) que l'on souhaite mesurer et pour secondaire un enroulement 5 comprenant plusieurs spires, par exemple dix, et un second transformateur T2 comprenant un circuit magnétique 3, par exemple également de forme torique. Ce second transformateur T2, placé dans un plan orthogonal au plan du premier transformateur Tl, a pour primaire un unique conducteur 9 passant dans le centre du tore 3, relié d'une part, à une première borne de 1'enroulement secondaire 5 du premier transformateur Tl, et d'autre part, à la seconde borne dudit enroulement secondaire 5 à travers un court-circuit 6. Le second transformateur T2 possède également un enroulement secondaire 7 bobiné autour du tore 3 et relié à une impédance de mesure 8 parcouru par un courant de sortie Is(t) qui' est 1''image du courant I (t) à mesurer.The method used in the invention consists in cascading at least two intensity transformers, the magnetic circuits of which consist of ferrites of different performance. Thus, with reference to FIG. 1a, a measuring device 1 according to the invention comprises a first transformer T1 constituted for example by a magnetic circuit 4 of toroidal shape, having for primary a conductor 2 crossed by the current I (t) that one wishes to measure and for secondary a winding 5 comprising several turns, for example ten, and a second transformer T2 comprising a magnetic circuit 3, for example also of toroidal shape. This second transformer T2, placed in a plane orthogonal to the plane of the first transformer Tl, has for primary a single conductor 9 passing through the center of the torus 3, connected on the one hand, to a first terminal of the secondary winding 5 of the first transformer Tl, and on the other hand, to the second terminal of said secondary winding 5 through a short circuit 6. The second transformer T2 also has a secondary winding 7 wound around the toroid 3 and connected to a measurement impedance 8 traversed by an output current Is (t) which is the image of the current I (t) to be measured.
La ferrite constituant le circuit magnétique 4 du premier transformateur Tl présente une faible perméabilité relative, notamment pour éviter, dans la gamme de mesure visée, une saturation par la composante continue du courant à mesurer I(t), et une trop forte influence de cette composante sur la fréquence de coupure basse, alors que la ferrite constituant le tore suivant 3, ou plus généralement 1'ensemble des tores suivants en cascade, présente une perméabilité beaucoup plus élevée pour assurer une fréquence de coupure basse la plus petite possible.The ferrite constituting the magnetic circuit 4 of the first transformer Tl has a low relative permeability, in particular to avoid, in the targeted measurement range, saturation by the DC component of the current to be measured I (t), and too strong influence of this component on the low cut-off frequency, while the ferrite constituting the following toroid 3, or more generally all of the following tori in cascade, has a much higher permeability to ensure the lowest possible low cut-off frequency.
Le courant à mesurer I(t) est appliqué au primaire 2 du premier transformateur d'intensité Tl dont le secondaire 5, parcouru par un courant Il(t), est placé en court-circuit à travers le primaire 9, 6 du second transformateur d'intensité T2.The current to be measured I (t) is applied to the primary 2 of the first intensity transformer Tl whose secondary 5, traversed by a current Il (t), is placed in short circuit through the primary 9, 6 of the second transformer of intensity T2.
Cet agencement est répété lorsque plusieurs transformateurs d'intensité sont cascades. L'enroulement secondaire du dernier transformateur d'intensité est fermée sur une impédance de mesure.This arrangement is repeated when several intensity transformers are cascaded. The secondary winding of the last current transformer is closed on a measurement impedance.
Le procédé selon l'invention permet ainsi d'obtenir:The method according to the invention thus makes it possible to obtain:
- une très large bande passante (de quelques KHz à quelques 100 MHz) ,- a very wide bandwidth (from a few KHz to a few 100 MHz),
- une gamme de courant efficace étendue (jusqu'à 1000 A efficace) ,- a wide effective current range (up to 1000 A effective),
- une très faible sensibilité de la bande passante à la composante continue du courant mesuré,- a very low sensitivity of the passband to the DC component of the measured current,
- une très faible susceptibilité électromagnétique. Dans un. exemple pratique de réalisation de l'invention mettant en oeuvre deux transformateurs d'intensité Tl, T2 selon l'agencement décrit en figure la, un dispositif de mesure 20 compact comprend un premier module de mesure 35 contenant notamment les deux transformateurs d'intensité Tl, T2 et un second module 34 contenant notamment la résistance de charge 8 et des moyens de connexion 33 du dispositif de mesure à des équipements extérieurs (non représentés) , en référence aux figures 2 à 5. Le premier module 35 comprend, en référence à la vue en coupe de la figure 2, un premier logement 25 conçu pour recevoir le premier transformateur d'intensité Tl et un second logement 26 conçu pour recevoir le second transformateur T2 et un tore Tm de filtrage de mode commun. Ces deux logements 25, 26 sont réalisés dans une pièce conductrice amagnétique 49 qui assure le blindage électromagnétique du dispositif de mesure. Dans le premier logement 25, le premier transformateur d'intensité Tl est placé autour d'un anneau 21 en matériau amagnétique de rayon sensiblement égal ou inférieur au rayon du passage intérieur du tore bobiné 5 et de longueur inférieure à la hauteur du logement 25 de sorte qu'un espacement prédéterminé e sépare l'extrémité libre de cet anneau 21 de la paroi du premier logement 25 qui est en vis à vis. Cet espacement, égal par exemple à 1/10 mm, est prévu pour faire en sorte que l'anneau 21, qui est relié électriquement au blindage 49, ne soit pas en court-circuit électrique avec ce blindage, ce qui aurait pour effet de créer une boucle entourant le circuit magnétique 4. L'anneau amagnétique 21, permet de supprimer la capacité primaire/secondaire et de diminuer 1'inductance de fuite primaire en haute fréquence (HF) . Le conducteur traversé par le courant à mesurer est placé dans le logement 31 constitué par la partie intérieure de l'anneau amagnétique. Le second logement 26 communique avec le premier logement 25 par un passage 27 étroit suffisant pour permettre le passage des conducteurs 9, 6 reliés aux bornes de l'enroulement secondaire 5. Dans ce second logement 26, les conducteurs précités transitent dans le trou central du tore Tm de filtrage en mode commun prévu pour diminuer les courants de circulation dans la pièce de blindage 49 du dispositif de mesure. Le courant du secondaire 5 du premier transformateur d'intensité Tl constitue le courant primaire du second transformateur d'intensité T2. Celui-ci est placé dans le second logement de telle façon que l'axe de symétrie du tore de ce second transformateur d'intensité T2 est orthogonal à l'axe de symétrie du tore du premier transformateur d'intensité Tl. Le premier conducteur 9, qui constitue le conducteur primaire du second transformateur d'intensité T2, est disposé coaxialement et de façon à réaliser un court-circuit à travers la partie 28 de la pièce de blindage 49 qui entoure le second transformateur d'intensité T2 et qui est reliée électriquement au second conducteur 6.- a very low electromagnetic susceptibility. In one. practical example of embodiment of the invention using two intensity transformers T1, T2 according to the arrangement described in FIG. la, a compact measuring device 20 comprises a first measuring module 35 containing in particular the two intensity transformers T1 , T2 and a second module 34 containing in particular the load resistor 8 and connection means 33 of the measurement device to external equipment (not shown), with reference to FIGS. 2 to 5. The first module 35 comprises, with reference to the sectional view of FIG. 2, a first housing 25 designed to receive the first intensity transformer Tl and a second housing 26 designed to receive the second transformer T2 and a common mode filtering torus Tm. These two housings 25, 26 are made in a non-magnetic conductive part 49 which provides the electromagnetic shielding of the measuring device. In the first housing 25, the first intensity transformer Tl is placed around a ring 21 of non-magnetic material with a radius substantially equal to or less than the radius of the interior passage of the wound toroid 5 and of length less than the height of the housing 25 of so that a predetermined spacing e separates the free end of this ring 21 from the wall of the first housing 25 which is opposite. This spacing, equal for example to 1/10 mm, is provided to ensure that the ring 21, which is electrically connected to the shield 49, is not in electrical short circuit with this shield, which would have the effect of creating a loop surrounding the magnetic circuit 4. The non-magnetic ring 21 makes it possible to eliminate the primary / secondary capacitance and to decrease the primary leakage inductance at high frequency (HF). The conductor through which the current to be measured is placed in the housing 31 formed by the inner part of the non-magnetic ring. The second housing 26 communicates with the first housing 25 through a narrow passage 27 sufficient to allow the passage of the conductors 9, 6 connected to the terminals of the secondary winding 5. In this second housing 26, the aforementioned conductors pass through the central hole of the torus Tm of common mode filtering intended to reduce the circulation currents in the shielding part 49 of the measuring device. The secondary current 5 of the first intensity transformer T1 constitutes the primary current of the second intensity transformer T2. This is placed in the second housing in such a way that the axis of symmetry of the torus of this second intensity transformer T2 is orthogonal to the axis of symmetry of the torus of the first intensity transformer Tl. The first conductor 9 , which constitutes the primary conductor of the second intensity transformer T2, is arranged coaxially and so as to produce a short circuit through the part 28 of the shielding piece 49 which surrounds the second intensity transformer T2 and which is connected electrically to the second conductor 6.
Le dispositif de mesure 20 réalisé en pratique se présente extérieurement, en référence à la figure 3, sous la forme d'un boîtier parallélépipédique constitué d'un premier boîtier 35 et d'un second boîtier 34 séparé du premier par une plaque de cuivre 30; ces deux boîtiers présentant une section identique et étant réalisés dans le même matériau conducteur amagnétique, par exemple du Durai. Le premier boîtier 35, traversé par un logement cylindrique 31, destiné à recevoir le conducteur 2 objet de la mesure de courant, est refermé par un couvercle plan 38 comprenant un trou cylindrique 39 coïncident avec le logement cylindrique 31 et quatre trous 37a, 37b, 37c, 37d placés aux quatre coins dudit couvercle 38 et agencés pour permettre le vissage de ce couvercle par rapport au premier boîtier 35. La plaque de cuivre 30, présentant une surface supérieure à la section commune des premier et second boîtiers 35, 34 constitue pour le dispositif de mesure selon l'invention une référence de masse. Le second boîtier 34, prévu notamment pour recevoir la résistance de mesure 8, comprend deux trous 61, 62 permettant la solidarisation mécanique de 1'ensemble constitué par le premier boîtier 35, la plaque de cuivre 30 et le second boîtier 34, et un connecteur 33 de type coaxial comprenant une armature externe 57 reliée électriquement via le corps du second boîtier 34 à une première borne de la résistance de mesure 8, et une âme coaxiale interne 36 reliée électriquement à la seconde borne de ladite résistance 8. Ainsi, la tension observée au niVeau du connecteur 33 est une image du courant traversant l'enroulement secondaire du transformateur d'intensité T2.The measuring device 20 produced in practice is presented externally, with reference to FIG. 3, in the form of a parallelepipedic box consisting of a first box 35 and a second box 34 separated from the first by a copper plate 30 ; these two boxes having an identical section and being made of the same non-magnetic conductive material, for example Durai. The first box 35, traversed by a cylindrical housing 31, intended to receive the conductor 2 which is the object of the current measurement, is closed by a flat cover 38 comprising a cylindrical hole 39 coinciding with the cylindrical housing 31 and four holes 37a, 37b, 37c, 37d placed at the four corners of said cover 38 and arranged to allow the screwing of this cover relative to the first housing 35. The copper plate 30, having a surface greater than the common section of the first and second housings 35, 34 constitutes for the measuring device according to the invention a mass reference. The second housing 34, provided in particular for receiving the measurement resistor 8, comprises two holes 61, 62 allowing the mechanical connection of the assembly constituted by the first housing 35, the copper plate 30 and the second housing 34, and a connector 33 of coaxial type comprising an external armature 57 electrically connected via the body of the second housing 34 to a first terminal of the measurement resistor 8, and an internal coaxial core 36 electrically connected to the second terminal of said resistance 8. Thus, the voltage observed at the level of the connector 33 is an image of the current passing through the secondary winding of the intensity transformer T2.
Dans la forme de réalisation pratique décrite en référence à la figure 4, les premier et second boîtiers 35, 34 sont réalisés par usinage de blocs homogènes parallélépipédiques d'un même matériau, par exemple du Durai, dans lesquels des évidements sont pratiqués pour recevoir les éléments constitutifs du dispositif de mesure selon l'invention. La figure 4 représente une vue de dessus des boîtiers 35, 34 nus qui constituent à la fois des structures d'accueil des composants et un blindage électromagnétique. Ainsi, le premier boîtier 35 comprend un premier logement annulaire 41 conçu pour recevoir le premier transformateur d'intensité Tl et présentant dans sa partie intérieure l'anneau amagnétique 21, un second logement 42, de forme sensiblement parallélépipédique, destiné à recevoir le tore Tm de filtrage en mode commun et un dispositif de connexion coaxial de l'enroulement secondaire du premier transformateur d'intensité Tl au conducteur primaire du second transformateur d'intensité T2, et un troisième logement 43, de forme cylindrique, destiné à recevoir le second transformateur d'intensité T2. Le second logement 42 communique avec le premier logement par un petit passage évidé de profondeur sensiblement plus faible que la profondeur des premier et second logements et conçu pour permettre le passage des conducteurs reliés à l'enroulement secondaire du premier transformateur d'intensité Tl. Le troisième logement 43 communique avec le second logement 42 par un petit orifice circulaire 60 destiné à recevoir une tige filetée ( non représentée sur la figure 4) faisant fonction de conducteur coaxial entre 1*'enroulement secondaire du premier transformateur d'intensité Tl et le primaire du second transformateur d'intensité T2. Le premier boîtier 35 comprend également quatre trous filetés 37a, 37b, 37c, 37d prévus pour recevoir quatre vis (non représentées) destinées à la fixation du couvercle 38 (cf. figure 3) par rapport audit premier boîtier 35, et deux trous filetés 47, 48 prévus pour recevoir deux vis (non représentées) de fixation du second boîùier 34 et de la plaque de cuivre 30 au premier boîtier 35. La plaque de cuivre 30 comprend deux trous de fixation 63, 64 respectivement en regard des trous 47, 48 ménagés dans le premier boîtier et des trous 62, 61 ménagés dans le second boîtier 34, un trou principal 45 prévu pour le passage d'une tige filetée et d'un trou auxiliaire prévu pour le passage des conducteurs de sortie de l'enroulement secondaire du second transformateur d'intensité T2. Le second boîtier 34 comprend un logement 46 prévu pour recevoir la résistance de mesure 8, un trou 44 réalisé sur sa paroi d'extrémité et situé dans l'axe du trou principal 45 de la plaque de cuivre 30, et du trou 60 de communication entre les second et troisième logements 42, 43, et des trous 62, 61 respectivement en regard des trous 63, 64 de la plaque de cuivre et des trous 47, 48 du premier boîtier 35, ces trous 62, 61 étant prévus pour recevoir des vis de fixation.In the practical embodiment described with reference to FIG. 4, the first and second housings 35, 34 are produced by machining homogeneous parallelepipedal blocks of the same material, for example Durai, in which recesses are made to receive the constituent elements of the measuring device according to the invention. FIG. 4 represents a top view of the bare housings 35, 34 which constitute both the structures for receiving the components and an electromagnetic shielding. Thus, the first housing 35 comprises a first annular housing 41 designed to receive the first intensity transformer Tl and having in its internal part the non-magnetic ring 21, a second housing 42, of substantially parallelepiped shape, intended to receive the torus Tm common mode filtering and a device for coaxial connection of the secondary winding of the first current transformer Tl to the primary conductor of the second current transformer T2, and a third housing 43, of cylindrical shape, intended to receive the second transformer of intensity T2. The second housing 42 communicates with the first housing by a small hollowed-out passage of depth substantially less than the depth of the first and second housing and designed to allow the passage of the conductors connected to the secondary winding of the first current transformer Tl. third recess 43 communicates with the second housing 42 by a small circular hole 60 for receiving a threaded rod (not shown in Figure 4) acting between the coaxial conductor 1 * secondary winding of the first current transformer Tl and the primary of the second intensity transformer T2. The first housing 35 also includes four threaded holes 37a, 37b, 37c, 37d designed to receive four screws (not shown) intended for fixing the cover 38 (cf. FIG. 3) relative to said first housing 35, and two threaded holes 47 , 48 designed to receive two screws (not shown) for fixing the second housing 34 and the copper plate 30 to the first housing 35. The copper plate 30 comprises two fixing holes 63, 64 respectively opposite the holes 47, 48 formed in the first housing and holes 62, 61 made in the second housing 34, a main hole 45 provided for the passage of a threaded rod and an auxiliary hole provided for the passage of the output conductors of the secondary winding of the second current transformer T2 . The second housing 34 comprises a housing 46 designed to receive the measurement resistor 8, a hole 44 made on its end wall and situated in the axis of the main hole 45 of the copper plate 30, and of the communication hole 60 between the second and third housings 42, 43, and holes 62, 61 respectively opposite the holes 63, 64 of the copper plate and the holes 47, 48 of the first housing 35, these holes 62, 61 being provided for receiving screw.
On va maintenant décrire l'assemblage des différents éléments du dispositif de mesure selon l'invention au sein des boîtiers, en référence à la figure 5.We will now describe the assembly of the various elements of the measuring device according to the invention within the housings, with reference to FIG. 5.
Le premier transformateur d'intensité Tl est placé dans le logement 41. Un premier élément isolant 51, par exemple un film isolant de faible épaisseur, est placé entre la périphérie extérieure du premier transformateur d'intensité Tl et la paroi 71 du logement cylindrique 41. L'enroulement secondaire 5 est de préférence constitué d'un faible nombre de spires, par exemple dix, de façon à limiter la valeur des inductances et capacités parasites. Ces spires sont réparties uniformément sur le circuit magnétique torique 4 et réalisées de préférence par mise en parallèle de plusieurs conducteurs élémentaires, par exemple quatre, afin de réduire l'inductance de fuite du transformateur d'intensité Tl et la résistance par effet de peau. A la sortie de l'enroulement secondaire 5, les conducteurs en parallèle sont réunis pour constituer respectivement le conducteur 9 destiné à être relié à la tige conductrice d'une vis 56 et le conducteur 6 destiné à être relié au blindage coaxial constitué par une partie du premier boîtier 35. Ces deux conducteurs 9, 6 passent dans l'orifice intérieur du tore Tm de filtrage en mode commun puis-sont reliés respectivement à une première rondelle 52 et à une seconde rondelle 54 séparées l'une de l'autre par une rondelle isolante 53, l'ensemble de ces trois rondelles 52, 54, 53 étant maintenu en contact contre une paroi du second logement 42 par un système de fixation comprenant la vis 56, un écrou 55 situé dans le second logement 42 et au contact de la première rondelle 52, et la tête 70 de la vis 56, située dans le logement 46 du second boîtier 34 et au contact de la plaque de cuivre 30. Le second transformateur d'intensité T2 est placé dans le troisième logement 43 du premier boîtier 35 et isolé galvaniquement des parois internes du troisième logement par un film isolant 51' . Son enroulement secondaire 7 est agencé sensiblement de la même façon que 1'enroulement secondaire du premier transformateur Tl: faible nombre de spires, conducteurs mis en parallèle et répartition uniforme sur le tore. Les conducteurs de sortie de l'enroulement secondaire 7 sont passés à travers le trou auxiliaire 65 de la plaque de cuivre 30 et aboutissent dans le logement 46 du second boîtier 34 pour être reliés aux bornes de la résistance de mesure 8, dont la valeur peut par exemple être choisie égale à 50 ohms. Une première borne 72 de la résistance de mesure 8 est reliée électriquement à l'embase 58 du connecteur 33, tandis que la seconde borne 73 de la résistance 8 est reliée électriquement à l'âme 36 dudit connecteur 33. Ce dernier est fixé à la paroi latérale du second boîtier 34 par un écrou 74 et son embase 58 est en contact électrique avec le second boîtier 34 et la plaque de cuivre 30. On peut ainsi prévoir un montage avec une rondelle isolante 59 du côté extérieur et un écrou 74 en matériau non conducteur, par exemple en Nylon. Bien d'autres agencements du connecteur de sortie peuvent être envisagés pour délivrer à l'extérieur du dispositif de mesure la tension aux bornes de la résistance de mesure.The first intensity transformer Tl is placed in the housing 41. A first insulating element 51, for example a thin insulating film, is placed between the outer periphery of the first intensity transformer Tl and the wall 71 of the cylindrical housing 41 The secondary winding 5 is preferably made up of a small number of turns, for example ten, so as to limit the value of the parasitic inductances and capacitances. These turns are distributed uniformly over the toroidal magnetic circuit 4 and preferably produced by placing several elementary conductors, for example four, in parallel, in order to reduce the leakage inductance of the intensity transformer T1 and the resistance by skin effect. At the outlet of the secondary winding 5, the parallel conductors are combined to respectively constitute the conductor 9 intended to be connected to the conductive rod of a screw 56 and the conductor 6 intended to be connected to the coaxial shield constituted by a part of the first housing 35. These two conductors 9, 6 pass into the internal orifice of the filtering torus Tm in common mode and then are connected respectively to a first washer 52 and to a second washer 54 separated from each other by an insulating washer 53, all of these three washers 52, 54, 53 being held in contact against a wall of the second housing 42 by a fixing system comprising the screw 56, a nut 55 located in the second housing 42 and at contact of the first washer 52, and the head 70 of the screw 56, located in the housing 46 of the second housing 34 and in contact with the copper plate 30. The second intensity transformer T2 is placed in the third housing 43 of the first housing 35 and galvanically isolated from the internal walls of the third housing by an insulating film 51 '. Its secondary winding 7 is arranged in substantially the same way as the secondary winding of the first transformer T1: low number of turns, conductors placed in parallel and uniform distribution over the toroid. The output conductors of the secondary winding 7 are passed through the auxiliary hole 65 of the copper plate 30 and terminate in the housing 46 of the second housing 34 to be connected to the terminals of the measurement resistor 8, the value of which can for example be chosen equal to 50 ohms. A first terminal 72 of the measurement resistor 8 is electrically connected to the base 58 of the connector 33, while the second terminal 73 of the resistance 8 is electrically connected to the core 36 of said connector 33. The latter is fixed to the side wall of the second housing 34 by a nut 74 and its base 58 is in electrical contact with the second housing 34 and the copper plate 30. It is thus possible to provide a mounting with an insulating washer 59 on the outside and a nut 74 made of material non-conductive, for example nylon. Many other arrangements of the output connector can be envisaged for delivering the voltage across the measurement resistor to the outside of the measurement device.
Le circuit magnétique du premier transformateur d'intensité Tl est, dans le présent exemple, réalisé en matériau ferrite présentant une faible perméabilité relative (par exemple, Ni-Z ayant unμR d'environ 300) et donc peu sensible à une composante continue du courant primaire. Le circuit du secon transformateur d'intensité T2, et plus généralement des éventuels autres trans-formateurs en cascade, est réalisé en matériau ferrite Zn-Mn présentant une perméabilité beaucoup plus élevée pour que la fréquence de coupure soit la plus basse possible.The magnetic circuit of the first intensity transformer Tl is, in the present example, made of ferrite material having a low relative permeability (for example, Ni-Z having a μ R of approximately 300) and therefore not very sensitive to a direct component of the primary current. The circuit of the second intensity transformer T2, and more generally of any other cascade transformers, is made of Zn-Mn ferrite material having a much higher permeability so that the cut-off frequency is as low as possible.
Il est à noter qu'au lieu d'utiliser, dans le premier transformateur, un circuit magnétique continu à faible perméabilité, on peut utiliser un circuit en un matériau à haute perméabilité, mais présentant un entrefer. Dans un tel cas, il est aussi possible de loger, dans cet entrefer, un détecteur de champ magnétique tel qu'une cellule de Hall, pour permettre la mesure de la composante continue du courant tel que cela a été décrit dans le brevet US 5,146,156.It should be noted that instead of using, in the first transformer, a continuous magnetic circuit with low permeability, it is possible to use a circuit made of a material with high permeability, but having an air gap. In such a case, it is also possible to house, in this air gap, a magnetic field detector such as a Hall cell, to allow the measurement of the DC component of the current as described in US Pat. No. 5,146,156 .
La figure lb montre une telle variante de réalisation du dispositif de la figure la, selon laquelle le circuit magnétique 4' du premier transformateur T ' λ présente un entrefer 10. Une cellule de Hall 11 est placée dans l'entrefer 10 et est reliée, au moyen de conducteurs représentés par la ligne 12, à un dispositif de mesure 13 pour la mesure de la composante continue ou de composantes à basses fréquences.FIG. 1B shows such an alternative embodiment of the device in FIG. 1a, according to which the magnetic circuit 4 'of the first transformer T' λ has an air gap 10. A Hall cell 11 is placed in the air gap 10 and is connected, by means of conductors represented by line 12, to a measuring device 13 for measuring the DC component or components at low frequencies.
On va maintenant décrire le fonctionnement du dispositif de mesure selon l'invention en référence aux figures la, 3 et 5 et présenter un mode de validation expérimentale en référence au figures 6 et 7.We will now describe the operation of the measuring device according to the invention with reference to FIGS. 1a, 3 and 5 and present an experimental validation mode with reference to FIGS. 6 and 7.
La présence d'un courant I (t) dans le conducteur 2 a pou effet de générer une induction magnétique dans le circuit magnétique 4 du premier transformateur Tl. Si le courant I(t) varie temporellement, la variation de l'induction magnétiqu entraîne la création d'un courant induit Il(t) dan l'enroulement secondaire. Ce courant induit parcoure le conducteurs * 9 et 6 passant par le centre du tore de filtrage en mode commun Tm et contribue à magnétiser le circuit magnétique 3 du second transformateur d'intensité T2. Une induction magnétique variable apparaît dans le circuit magnétique 3 en réponse à la circulation du courant dans les conducteurs 6 et 9, et contribue à la création d'un courant induit is(t) dans l'enroulement secondaire 7 du second transformateur d'intensité T2 qui est refermé sur la résistance de mesure 8. La tension observée aux bornes de la résistance de mesure 8 est alors une image homothétique du courant puisque les différentes grandeurs physiques: courant, induction magnétique, tension sont liées par des relations linéaires. En effet, les matériaux utilisés pour les circuits magnétiques des transformateurs d'intensité sont choisis de telle sorte qu'une linéarité quasi-parfaite soit observée entre le courant primaire et le courant secondaire. La faible perméabilité relative du matériau utilisé pour le circuit magnétique du premier transformateur d'intensité permet d'éviter une saturation due à l'existence d'une composante continue du courant à mesurer. La mise en oeuvre de transformateurs d'intensité en cascade, deux dans l'exemple décrit, permet d'utiliser des enroulements secondaires à faible nombre de spires et par conséquent de réduire sensiblement la valeur des composants parasites apparaissant dans le montage équivalent du dispositif.The presence of a current I (t) in the conductor 2 has the effect of generating a magnetic induction in the magnetic circuit 4 of the first transformer Tl. If the current I (t) varies temporally, the variation of the magnetic induction causes the creation of an induced current Il (t) in the secondary winding. This induced current flows through the conductors * 9 and 6 passing through the center of the filter core in common mode Tm and contributes to magnetize the magnetic circuit 3 of the second intensity transformer T2. A variable magnetic induction appears in the magnetic circuit 3 in response to the flow of current in the conductors 6 and 9, and contributes to the creation of an induced current i s (t) in the secondary winding 7 of the second transformer of intensity T2 which is closed on the measurement resistor 8. The voltage observed at the terminals of the measurement resistor 8 is then a homothetic image of the current since the different physical quantities: current, magnetic induction, voltage are linked by linear relations. Indeed, the materials used for the magnetic circuits of the intensity transformers are chosen so that a quasi-perfect linearity is observed between the primary current and the secondary current. The low relative permeability of the material used for the magnetic circuit of the first current transformer makes it possible to avoid saturation due to the existence of a continuous component of the current to be measured. The use of cascade current transformers, two in the example described, makes it possible to use secondary windings with a small number of turns and consequently to significantly reduce the value of the parasitic components appearing in the equivalent assembly of the device.
Le dispositif de mesure 20 selon l'invention a été mis en oeuvre dans un montage 80 de validation expérimentale comprenant une source d'alimentation continue 81, un condensateur de filtrage 82, une charge 85, notamment une charge inductive telle qu'un moteur électrique à courant continu, une diode de roue libre 84 montée en antiparallèle sur la charge 85, et un transistor de puissance 86, par exemple un transistor MOSFET. Le drain du transistor 86 est relié à une borne de la charge 85 connectée à l'anode de la diode de roue libre 84, sa grille est reliée à un circuit de commande de grille 83 et sa source est reliée à la masse du montage. Le courant de source I(t) est mesuré d'une part par le dispositif 20 de mesure selon l'invention, et d'autre part, par observation de la chute de tension aux bornes d'une inductance L calibrée présente entre la source et la masse et de très faible valeur. La tension Vs(t) générée par le dispositif de mesure 20 est multipliée par un coefficient (1/ ) pour délivrer une image dynamique Iτ(t) du courant à mesurer I(t) .The measuring device 20 according to the invention has been used in an experimental validation setup 80 comprising a continuous power source 81, a filtering capacitor 82, a load 85, in particular an inductive load such as an electric motor. direct current, a freewheeling diode 84 mounted in antiparallel on the load 85, and a power transistor 86, for example a MOSFET transistor. The drain of transistor 86 is connected to a terminal of the load 85 connected to the anode of the freewheeling diode 84, its gate is connected to a gate control circuit 83 and its source is connected to the ground of the assembly. The source current I (t) is measured on the one hand by the measuring device 20 according to the invention, and on the other hand, by observation of the voltage drop across a calibrated inductance L present between the source and mass and very low value. The voltage Vs (t) generated by the measuring device 20 is multiplied by a coefficient (1 /) to deliver a dynamic image I τ (t) of the current to be measured I (t).
La chute de tension aux bornes de l'inductance L est observée au moyen d'une sonde 87, éventuellement atténuatrice si le niveau crête de tension le justifie, et est ensuite intégrée pour délivrer une image IR(t) du courant I (t) à mesurer. Ce procédé de mesure, qui n'offre cependant aucun isolement galvanique, peut fournir du fait de sa simplicité de mise en oeuvre, une mesure de référence permettant de valider le procédé selon 1'invention.The voltage drop across the inductance L is observed by means of a probe 87, possibly attenuating if the peak voltage level justifies it, and is then integrated to deliver an image I R (t) of the current I (t ) to measure. This measurement method, which does not however offer any galvanic isolation, can provide, because of its simplicity of implementation, a reference measurement making it possible to validate the method according to the invention.
Si on étudie la réponse en courant à un front montant appliqué sur la grille du transistor 86 provoquent la conduction de ce dernier, on obtient les formes d'onde 7.a et 7.b correspondant respectivement aux courants IR(t) et Iτ(t) obtenus avec la sonde inductive à intégration et avec le dispositif de mesure selon l'invention. On constate une très bonne correspondance entre la forme d'onde de référence IR(t) et la forme d'onde Iτ(t) issue du dispositif selon l'invention, qui met en évidence les performances du dispositif selon l'invention en termes de bande passante et de précision.If we study the current response to a rising edge applied to the gate of transistor 86 cause the conduction of the latter, we obtain the waveforms 7.a and 7.b corresponding respectively to the currents I R (t) and I τ (t) obtained with the inductive integration probe and with the measuring device according to the invention. There is a very good correspondence between the reference waveform I R (t) and the waveform I τ (t) from the device according to the invention, which highlights the performance of the device according to the invention in terms of bandwidth and accuracy.
Il est ainsi possible de réaliser des dispositifs de mesure présentant une faible sensibilité aux perturbations électromagnétiques et des performances élevées. A titre d'exemple, on a pu obtenir pour un dispositif de mesure effectivement réalisé, les caractéristiques suivantes:It is thus possible to produce measuring devices having a low sensitivity to electromagnetic disturbances and high performance. By way of example, the following characteristics have been obtained for a measuring device actually produced:
une sensibilité de 100 mV/A sur une charge de 50 Ohms;a sensitivity of 100 mV / A on a load of 50 Ohms;
une bande passante (à -3 dB) : de 4 kHz à 300 MHz; une faible sensibilité au courant continu: un courant continu de 20 A élève la fréquence de coupure basse d'un facteur 2; et un courant efficace vrai nominal de 50 A. a bandwidth (at -3 dB): from 4 kHz to 300 MHz; low sensitivity to direct current: a direct current of 20 A raises the low cut-off frequency by a factor of 2; and a nominal true effective current of 50 A.

Claims

REVENDICATIONS
1. Procédé pour la mesure de composantes dynamiques, à fréquences supérieures au Mégahertz, dans un courant électrique (I(t)) circulant dans un conducteur (2), ce procédé comprenant une première étape de transformation par couplage magnétique du courant à mesurer (I(t)) en un premier courant induit dι(t)), et au moins une deuxième étape de transformation de courant par couplage magnétique dans laquelle le courant d'entrée est le courant induit de l'étape de transformation précédente, le courant induit de la dernière étape de transformation (Is(t)) étant mesuré pour obtenir une image des composantes dynamiques du courant à mesurer (I(t)), caractérisé en ce que, dans la première étape de transformation, le couplage magnétique est obtenu par mise en oeuvre d'un circuit magnétique (4) à réluctance relativement élevée pour limiter à un niveau voulu l'incidence d'une composante continue du courant à mesurer (I(t)) sur la1. Method for measuring dynamic components, at frequencies higher than megahertz, in an electric current (I (t)) flowing in a conductor (2), this method comprising a first step of transformation by magnetic coupling of the current to be measured ( I (t)) into a first induced current dι (t)), and at least a second current transformation step by magnetic coupling in which the input current is the induced current from the previous transformation step, the current armature of the last transformation step (Is (t)) being measured to obtain an image of the dynamic components of the current to be measured (I (t)), characterized in that, in the first transformation step, the magnetic coupling is obtained by implementing a relatively high reluctance magnetic circuit (4) to limit to a desired level the incidence of a direct component of the current to be measured (I (t)) on the
•mesure des composantes dynamiques, et que, dans chacune des étapes successives de transformation, le couplage magnétique est obtenu par mise en oeuvre d'un circuit magnétique respectif (3) présentant une réluctance sensiblement plus faible pour minimiser la fréquence de coupure basse de la mesure. • measurement of the dynamic components, and that, in each of the successive transformation steps, the magnetic coupling is obtained by implementing a respective magnetic circuit (3) having a significantly lower reluctance to minimize the low cut-off frequency of the measured.
2. Procédé selon la revendication 1, caractérisé en ce que, dans la première étape de transformation, le couplage magnétique est obtenu par la mise en oeuvre d'un circuit magnétique en un matériau à perméabilité magnétique élevée, omportant au moins un entrefer.2. Method according to claim 1, characterized in that, in the first transformation step, the magnetic coupling is obtained by the use of a magnetic circuit made of a material with high magnetic permeability, including at least one air gap.
3. Procédé selon la revendication 2, caractérisé en ce que l'on mesure le champ magnétique dans ledit entrefer pour obteni une mesure de la composante continue du courant à mesurer.3. Method according to claim 2, characterized in that the magnetic field is measured in said air gap to obtain a measurement of the DC component of the current to be measured.
4. Dispositif pour la mesure de composantes dynamiques, fréquences supérieures au Mégahertz, dans un courant électriqu (I(t)) circulant dans un conducteur (2), caractérisé en ce qu'i comprend un ensemble d'au moins deux transformateurs d'intensit (Tl, T2) de courant disposés en cascade, un premier transformateur d'intensité (Tl) ayant pour primaire le conducteur (2) * parcouru par le courant à mesurer, et un dernier transformateur d'intensité (T2) possédant un enroulement secondaire (7) fermé sur une impédance de mesure (8), chaque transformateur suivant le premier ayant pour primaire un conducteur court-circuitant électriquement l'enroulement secondaire du transformateur précédent, caractérisé en ce que le circuit magnétique (4) du premier transformateur d'intensité (Tl) est réalisé en un matériau ferromagnétique présentant une perméabilité relative suffisamment faible pour limiter à un niveau voulu l'incidence d'une composante continue du courant à mesurer sur la mesure des composantes dynamiques, et que les circuits magnétiques (3) des transformateurs d'intensité de rang supérieur à un (T2) sont réalisés en un matériau ferromagnétique présentant une perméabilité relative sensiblement plus élevée.4. Device for measuring dynamic components, frequencies higher than Megahertz, in an electric current (I (t)) flowing in a conductor (2), characterized in that i comprises a set of at least two transformers of intensifies (Tl, T2) of current arranged in cascade, a first intensity transformer (Tl) having for its primary the conductor (2) * traversed by the current to be measured, and a last intensity transformer (T2) having a secondary winding (7) closed on a measurement impedance (8), each transformer following the first having for primary a conductor electrically shorting the secondary winding of the preceding transformer, characterized in that the magnetic circuit (4) of the first transformer intensity (Tl) is made of a ferromagnetic material having a sufficiently low relative permeability to limit to a desired level the impact of a continuous component of the current to be measured on the measurement of the dynamic components, and that the magnetic circuits (3) intensity transformers of rank greater than one (T2) are made of a ferromagnetic material having a significantly higher relative permeability lifted.
5. Dispositif pour la mesure de composantes dynamiques, à fréquences supérieures au Mégahertz, dans un courant électrique (I(t)) circulant dans un conducteur (2), caractérisé en ce qu'il comprend un ensemble d'au moins deux transformateurs d'intensité de courant disposés en cascade, un premier transformateur d'intensité ayant pour primaire le conducteur parcouru par le courant à mesurer, et un dernier transformateur ' d'intensité possédant un enroulement secondaire fermé sur une impédance de mesure, chaque transformateur suivant le premier ayant pour primaire un conducteur court-circuitant électriquement l'enroulement secondaire du transformateur précédent, caractérisé en ce que les circuits magnétiques des transformateurs d'intensité sont réalisés en un matériau ferromagnétique présentant une perméabilité relativement élevée et que le circuit magnétique du premier transformateur d'intensité (Tl) comporte au moins un entrefer.5. Device for measuring dynamic components, at frequencies higher than megahertz, in an electric current (I (t)) flowing in a conductor (2), characterized in that it comprises a set of at least two transformers d intensity of current arranged in cascade, a first current transformer having primary to the conductor through which the current to be measured, and a final processor 'intensity having a closed secondary winding on a measuring impedance, each processor according to the first having for primary a conductor electrically shorting the secondary winding of the preceding transformer, characterized in that the magnetic circuits of the intensity transformers are made of a ferromagnetic material having a relatively high permeability and that the magnetic circuit of the first transformer intensity (Tl) comprises at least one air gap.
6. Dispositif selon la revendication 5, caractérisé en c qu'il comporte des moyens pour mesurer le champ magnétique dan ledit entrefer. 6. Device according to claim 5, characterized in that it comprises means for measuring the magnetic field in said air gap.
7. Dispositif selon l'une quelconque des revendications 4 à7. Device according to any one of claims 4 to
6, caractérisé en ce que l'enroulement secondaire (5) du premier transformateur d'intensité (Tl) comprend un nombre prédéterminé de spires constituées par la mise en parallèle d'un nombre prédéterminé de conducteurs élémentaires et réparties régulièrement sur le circuit magnétique (4) dudit premier transformateur (Tl) .6, characterized in that the secondary winding (5) of the first intensity transformer (Tl) comprises a predetermined number of turns constituted by the parallel connection of a predetermined number of elementary conductors and distributed regularly over the magnetic circuit ( 4) of said first transformer (Tl).
8. Dispositif selon l'une quelconque des revendications 4 à8. Device according to any one of claims 4 to
7, caractérisé en ce qu'il comprend en outre, au niveau de chaque liaison entre l'enroulement secondaire (5) d'un transformateur d'intensité (Tl) et le primaire du transformateur d'intensité suivant (T2) réalisée au moyen de deux conducteurs (9, 6), un tore (Tm) de filtrage de mode commun traversé en son centre par ces deux conducteurs (9, 6) .7, characterized in that it further comprises, at each connection between the secondary winding (5) of an intensity transformer (Tl) and the primary of the following intensity transformer (T2) produced by means two conductors (9, 6), a common mode filtering torus (Tm) crossed in its center by these two conductors (9, 6).
9. Dispositif selon l'une quelconque des revendications 4 à9. Device according to any one of claims 4 to
8, caractérisé en ce qu'il comprend en outre des moyens (35) pour blinder au moins une partie des composants dudit dispositif et notamment les transformateurs d'intensité.8, characterized in that it further comprises means (35) for shielding at least part of the components of said device and in particular the current transformers.
10. Dispositif selon la revendication 9, caractérisé en ce qu'il comrend un boîtier (35) réalisé en matériau amagnétique conducteur et conçu pour contenir une partie des composants (Tl, T2, Tm) dudit dispositif (1), ce boîtier (35) étant pourvu d'un trou (31) pour recevoir le conducteur (2) traversé par le courant à mesurer (I(t) ) .10. Device according to claim 9, characterized in that it comprises a box (35) made of non-conductive non-magnetic material and designed to contain part of the components (Tl, T2, Tm) of said device (1), this box (35 ) being provided with a hole (31) for receiving the conductor (2) through which the current to be measured (I (t)) passes.
11. Dispositif selon la revendication 8, caractérisé en ce que le circuit magnétique (4) du premier transformateur d'intensité (Tl) est un tore présentant une fenêtre circulaire sensiblement en correspondance avec le trou (31) dudit boîtier (35), et en ce qu'un anneau amagnétique conducteur (21) est prévu à l'intérieur de ladite fenêtre pour recevoir le conducteur (2) traversé par le courant à -mesurer (I(t)), cet anneau (21) ayant l'une de ses extrémités en contact mécanique et électrique ave une première portion de paroi interne (49) du boîtier (35) .11. Device according to claim 8, characterized in that the magnetic circuit (4) of the first intensity transformer (Tl) is a toroid having a circular window substantially in correspondence with the hole (31) of said housing (35), and in that a conductive non-magnetic ring (21) is provided inside said window to receive the conductor (2) through which the current to be measured (I (t)) passes, this ring (21) having one of its ends in mechanical and electrical contact with a first portion of the internal wall (49) of the housing (35).
12. Dispositif selon la revendication 11, caractérisé en c que l'autre extrémité de l'anneau est espacée d'une second portion de paroi interne du boîtier (35) .12. Device according to claim 11, characterized in that the other end of the ring is spaced from a second portion of the inner wall of the housing (35).
13. Dispositif selon l'une quelconque des revendications 4 12, caractérisé en ce qu'il comprend un premier boîtier (35) pou contenir les deux transformateurs d'intensité (Tl, T2) , et u second boîtier (34) contenant l'impédance de mesure (8) et de moyens de sortie (33) pour acquérir la tension aux bornes d ladite impédance de mesure (8), ces deux boîtiers (35, 34) étan réalisés dans un matériau amagnétique conducteur et séparés pa une pièce conductrice intermédiaire (30) , notamment en cuivre, prévue pour une connexion de masse.13. Device according to any one of claims 4 to 12, characterized in that it comprises a first housing (35) for containing the two intensity transformers (T1, T2), and a second housing (34) containing the measurement impedance (8) and output means (33) for acquiring the voltage across said measurement impedance (8), these two tin boxes (35, 34) made of a non-conductive magnetic material and separated by a conductive part intermediate (30), in particular made of copper, provided for a ground connection.
14. Dispositif selon la revendication 13, caractérisé en c que le premier boîtier (35) comporte un premier logement (41) d forme sensiblement cylindrique pour recevoir le premie transformateur d'intensité (Tl) , et un second logement (42) pou recevoir des moyens de connexion intermédiaire (52, 53, 54, 55) entre le premier transformateur d'intensité (Tl) et le secon transformateur d'intensité (T2) , ce second logement (42 communiquant avec le premier logement (41) par un premier passag (27).14. Device according to claim 13, characterized in that the first housing (35) comprises a first housing (41) of substantially cylindrical shape for receiving the first intensity transformer (Tl), and a second housing (42) for receiving intermediate connection means (52, 53, 54, 55) between the first intensity transformer (T1) and the second intensity transformer (T2), this second housing (42 communicating with the first housing (41) by a first pass (27).
15. Dispositif selon la revendication 14, caractérisé en c que le premier boîtier (35) comporte en outre un troisièm logement (43), ayant sensiblement la forme d'un cylindre d'ax perpendiculaire à l'axe du premier logement (41), pour recevoi le second transformateur d'intensité (T2), ce troisième logemen (43) communiquant avec le second logement (42) par un trou (60 ménagé dans la paroi qui les sépare et ayant pour paroi la pièc conductrice intermédiaire (30) . 15. Device according to claim 14, characterized in that the first housing (35) further comprises a third housing (43), having substantially the shape of an axis cylinder perpendicular to the axis of the first housing (41) , to receive the second intensity transformer (T2), this third housing (43) communicating with the second housing (42) through a hole (60 formed in the wall which separates them and having for wall the intermediate conductive part (30) .
16. Dispositif selon la revendication 15 , ' caractérisé en ce que les moyens de connexion intermédiaire comprennent une première pièce centrale (56) reliée par un premier conducteur (9) à une première borne de l' enroulement secondaire (5) et placée dans la fenêtre du second transformateur d' intensité (T2) , et une seconde pièce (54 ) réalisant, en coopération avec une portion du premier boîtier (35) et la pièce conductrice intermédiaire (30) , un court-circuit coaxial autour de' la première pièce centrale (56) de façon à réaliser une boucle de courant autour du circuit magnétique (3) du second transformateur d' intensité (T2) , cette seconde pièce (54) étant reliée par un second conducteur (6) à la seconde borne de l ' enroulement secondaire ( 5) du premier transformateur d' intensité (Tl) . 16. Device according to claim 15, 'characterized in that the intermediate connection means comprise a first central part (56) connected by a first conductor (9) to a first terminal of the secondary winding (5) and placed in the window of the second current transformer (T2), and a second part (54) providing, in cooperation with a portion of the first housing (35) and the conductive part intermediate (30), a coaxial shorting around 'the first central part (56) so as to form a current loop around the magnetic circuit (3) of the second current transformer (T2), this second part (54) being connected by a second conductor (6) to the second terminal of. the secondary winding (5) of the first current transformer (Tl).
PCT/CH1994/000100 1993-06-01 1994-05-31 Method and device for measuring the dynamic components of an electric current in the presence of a continuous component WO1994028429A1 (en)

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FR9306518A FR2706040B1 (en) 1993-06-01 1993-06-01 Current measurement method and device implementing this method.
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Publication number Priority date Publication date Assignee Title
EP2293308A3 (en) * 2004-10-29 2014-08-20 Aperam Alloys Imphy Nanocrystalline core for electricity meter
EP3208816A1 (en) * 2016-02-17 2017-08-23 General Electric Technology GmbH Current transformer having secondary transformation components into its base
CN109834521A (en) * 2019-01-23 2019-06-04 南京航空航天大学 A kind of non-contact rotary ultrasonic machining Dynamic Signal extraction element

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FR2706040A1 (en) 1994-12-09
DE4493433T1 (en) 1995-07-20
CH689765A5 (en) 1999-10-15

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