EP0074297B1 - Hybrid compensated current transformer - Google Patents

Hybrid compensated current transformer Download PDF

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Publication number
EP0074297B1
EP0074297B1 EP19820401529 EP82401529A EP0074297B1 EP 0074297 B1 EP0074297 B1 EP 0074297B1 EP 19820401529 EP19820401529 EP 19820401529 EP 82401529 A EP82401529 A EP 82401529A EP 0074297 B1 EP0074297 B1 EP 0074297B1
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Prior art keywords
current
sensor according
frequency
circuit
current sensor
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German (de)
French (fr)
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EP0074297A1 (en
EP0074297B2 (en
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Pierre Schueller
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Merlin Gerin SA
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Merlin Gerin SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase ac
    • H01F38/28—Current transformers
    • H01F38/32—Circuit arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase ac
    • H01F38/28—Current transformers
    • H01F38/30—Constructions
    • H01F2038/305—Constructions with toroidal magnetic core

Definitions

  • the invention relates to a current sensor according to the preamble of claim 1.
  • Such a device of the prior art is described in document DE-B-1,281,545, in which the secondary winding delivers an output voltage proportional to dh / dt, that is to say to the variation of the current primary l 1 during time t.
  • the secondary time constant of such a non-magnetic or magnetic circuit sensor with an air gap is less than 10 microseconds.
  • the output voltage is applied to an integrator circuit RC of the series resistance and capacitor type, intended to deliver a signal more or less proportional to the primary current l 1 .
  • Such a sensor does not cause heating but is not suitable for producing a power signal.
  • Conventional sensors also use current transformers with non-gap magnetic cores, the secondary winding of which delivers a measurement signal proportional to the primary current, the proportionality factor corresponding to the transformation ratio of the transformer.
  • the secondary time constant is greater than 100 milliseconds.
  • This type of transformer is capable of delivering a measurement and power signal, but the section of the magnetic circuit must be large enough to avoid saturation of the magnetic circuit during the passage of large currents in the line. This results in a large size and a high manufacturing cost.
  • the object of the invention is to remedy these drawbacks and to produce an improved inductive current sensor capable of delivering a predetermined secondary power, with reduced heating and without any auxiliary power source for the operation of the electronic equipment.
  • the inductive sensor according to the invention is characterized in that it is of the hybrid type whose secondary time constant t 2 is defined by the relation n 2 / R 0 (R 1 + R 2 ) of between 10 microseconds and 100 milliseconds .
  • the range of values of the time constant t 2 is determined by the total length of the non-magnetic gap (s) between 0.5 and 20 millimeters, and by the value of the load resistance R 2 between 10 and 1000 Ohms.
  • the secondary winding of the hybrid sensor cooperates with a frequency compensation circuit connected to the terminals of the load resistor R 2 , and delivering a measurement image signal whose amplitude is substantially constant when the frequency f of the primary current 1, is within a predetermined range around a central frequency f o of compensation.
  • Said frequency compensation circuit includes a phase shift system for phasing the measurement image signal with the primary current l 1 to be checked when the frequency of the latter corresponds to the central frequency f o .
  • the image signal for measuring the compensation circuit is injected into an electronic processing system delivering a tripping order to a control coil of a circuit breaker when the image signal exceeds a predetermined threshold, l 'supply to the treatment system by means of the uncompensated voltage U 2 taken from the terminals of the load resistor R 2 .
  • the hybrid current sensor 10 comprises a magnetic circuit CM in the form of a torus provided with one or more air gaps 12 of total length e.
  • the magnetic circuit CM is crossed by a line 14 of an alternating current supply network, the line 14 playing the role of primary winding traversed by a current l 1 to be checked.
  • a secondary winding 16 is wound on the toroid and comprises n turns of ohmic resistance R l .
  • a load resistor R 2 is connected to the output terminals of the secondary winding.
  • the secondary time constant t 2 of the hybrid sensor is defined by the relation n 2 / Re (R l + R2), Re being the total reluctance of the magnetic circuit CM.
  • the secondary winding 16 delivers an output current 1 2 representing a vector quantity whose module and phase shift ⁇ relative to the primary current l 1 are illustrated by the diagrams of FIG. 2 as a function of the secondary time constant t 2 and for a given frequency f of the primary current l 1 .
  • the modulus expressed by the ratio nl 2 / l 1 varies between 0 and 1 when the time constant t 2 increases.
  • the sensor is a conventional current transformer.
  • time constants t 2 of less than 10 microseconds the sensor is of the non-magnetic type.
  • the hybrid sensor occupies the intermediate zone.
  • the section of the secondary winding of an inductive sensor being proportional to the product nl 2 ′ it can be seen in FIG. 2 that it is the current transformer where nl 2 is close to l 1 , which requires the most winding volume important and which is therefore the most expensive.
  • the torus has an air gap 12 in FIG. 1 has been replaced by a rectangular magnetic circuit CM with two air gaps 12a, 12b, comprising two elementary U-shaped parts located opposite one another, so as to confine a window crossed by the line 14.
  • a secondary winding 16 single is wound on the magnetic circuit CM.
  • the secondary winding is formed by two coils 16a, 16b connected in series or in parallel, the rest being identical to the sensor of FIG. 3.
  • the relative position of the coils 16a, 16b with respect to the air gaps can be arbitrary.
  • the characteristics of the hybrid sensor 10 according to FIGS. 1 to 3 nevertheless depend on the frequency variation of the current l 1 to be measured.
  • the amplitude and the phase of the output voltage U 2 at the terminals of the secondary winding 16 indeed vary with the frequency. This is why a frequency compensation circuit 18 (FIG. 5) is associated with the hybrid sensor.
  • the frequency compensation circuit 18 (fig. 5) is formed by a series circuit RC connected in parallel to the terminals of the load resistor R 2 .
  • the image signal of the current l 1 to be measured is the voltage U c across the capacitor C.
  • the values of R and C of circuit 18 are defined by the following relation: where f o is the central compensation frequency (55 Hz for example).
  • the compensation circuit 18 is constituted by a series circuit with an inductance Let resistance R, connected in parallel to the terminals of R 2 , the image signal for measuring the current l 1 in this case being the voltage U R at the terminals of resistance R.
  • FIG. 7 compares the amplitudes of the output voltages U 2 and U c before and after the compensation as a function of the frequency f of the current to be measured, the values of the time constant t 2 and of the intensity of the current 1, being data. It will be noted that the amplitude of the image voltage U c is substantially constant when the frequency f of the current l 1 is within a predetermined range around the central frequency f o of compensation. The current l 1 to be measured and the voltage Uc are in phase when the frequency of the current l 1 is equal to the central frequency f o .
  • FIG. 8 represents the application of a compensated hybrid sensor described with reference to FIG. 5, and delivering a combined secondary measurement and supply signal to an electronic control device or static trip device of a circuit breaker with its own current, one of the contacts 20 of which is inserted in line 14.
  • the measurement image signal U c of the compensation circuit 18 is injected into an electronic processing system 22 via a first connecting conductor 24.
  • the uncompensated voltage U 2 of the secondary winding 16 will be advantageously used for supplying the treatment 22 thanks to a second connecting conductor 26.
  • the output of the processing system 22 delivers a tripping order to a control coil 28 which conventionally causes the mechanism to be unlocked. 30 and the opening of the contacts 20 of the protective circuit breaker.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Transformers For Measuring Instruments (AREA)

Description

L'invention est relative à un capteur de courant selon le préambule de la revendication 1.The invention relates to a current sensor according to the preamble of claim 1.

Un tel dispositif de l'art antérieur est décrit dans le document DE-B-1.281.545, dans lequel l'enroulement secondaire délivre une tension de sortie proportionnelle à dh/dt, c'est-à-dire à la variation du courant primaire l1 pendant le temps t. La constante de temps secondaire d'un tel capteur amagnétique ou à circuit magnétique à entrefer est inférieure à 10 microsecondes. La tension de sortie est appliquée à un circuit intégrateur RC du type à résistance et condensateur série, destiné à délivrer un signal plus ou moins proportionnel au courant primaire l1. Un tel capteur ne provoque pas d'échauffement mais n'est pas adapté pour produire un signal de puissance.Such a device of the prior art is described in document DE-B-1,281,545, in which the secondary winding delivers an output voltage proportional to dh / dt, that is to say to the variation of the current primary l 1 during time t. The secondary time constant of such a non-magnetic or magnetic circuit sensor with an air gap is less than 10 microseconds. The output voltage is applied to an integrator circuit RC of the series resistance and capacitor type, intended to deliver a signal more or less proportional to the primary current l 1 . Such a sensor does not cause heating but is not suitable for producing a power signal.

Les capteurs conventionnels utilisent d'autre part des transformateurs de courant à noyaux magnétiques sans entrefer dont l'enroulement secondaire délivre un signal de mesure proportionnel au courant primaire, le facteur de proportionnalité correspondant au rapport de transformation du transformateur. La constante de temps secondaire est supérieure à 100 millisecondes. Ce type de transformateur est capable de délivrer un signal de mesure et de puissance, mais la section du circuit magnétique doit être assez importante pour éviter la saturation du circuit magnétique lors du passage de courants importants dans la ligne. Il en résulte un encombrement important et un coût de fabrication élevé.Conventional sensors also use current transformers with non-gap magnetic cores, the secondary winding of which delivers a measurement signal proportional to the primary current, the proportionality factor corresponding to the transformation ratio of the transformer. The secondary time constant is greater than 100 milliseconds. This type of transformer is capable of delivering a measurement and power signal, but the section of the magnetic circuit must be large enough to avoid saturation of the magnetic circuit during the passage of large currents in the line. This results in a large size and a high manufacturing cost.

L'invention a pour but de remédier à ces inconvénients et de réaliser un capteur de courant inductif perfectionné capable de délivrer une puissance secondaire prédéterminée, avec un échauffement réduit et sans aucune source auxiliaire d'alimentation pour le fonctionnement de l'appareillage électronique.The object of the invention is to remedy these drawbacks and to produce an improved inductive current sensor capable of delivering a predetermined secondary power, with reduced heating and without any auxiliary power source for the operation of the electronic equipment.

Le capteur inductif selon l'invention est caractérisé en ce qu'il est du type hybride dont la constante de temps secondaire t2 est définie par la relation n2/R0(R1 + R2) comprise entre 10 microsecondes et 100 millisecondes. La fourchette des valeurs de la constante de temps t2 est déterminée par la longueur totale de ou des entrefers amagnétiques du noyau comprise entre 0,5 et 20 millimètres, et par la valeur de la résistance de charge R2 comprise entre 10 et 1 000 Ohms.The inductive sensor according to the invention is characterized in that it is of the hybrid type whose secondary time constant t 2 is defined by the relation n 2 / R 0 (R 1 + R 2 ) of between 10 microseconds and 100 milliseconds . The range of values of the time constant t 2 is determined by the total length of the non-magnetic gap (s) between 0.5 and 20 millimeters, and by the value of the load resistance R 2 between 10 and 1000 Ohms.

Selon une caractéristique de l'invention, l'enroulement secondaire du capteur hybride coopère avec un circuit de compensation en fréquence connecté aux bornes de la résistance de charge R2, et délivrant un signal image de mesure dont l'amplitude est sensiblement constante lorsque la fréquence f du courant primaire 1, est comprise dans une fourchette prédéterminée autour d'une fréquence centrale fo de compensation. Ledit circuit de compensation en fréquence comporte un système déphaseur de mise en phase du signal image de mesure avec le courant primaire l1 à contrôler lorsque la fréquence de ce dernier correspond à la fréquence centrale fo.According to a characteristic of the invention, the secondary winding of the hybrid sensor cooperates with a frequency compensation circuit connected to the terminals of the load resistor R 2 , and delivering a measurement image signal whose amplitude is substantially constant when the frequency f of the primary current 1, is within a predetermined range around a central frequency f o of compensation. Said frequency compensation circuit includes a phase shift system for phasing the measurement image signal with the primary current l 1 to be checked when the frequency of the latter corresponds to the central frequency f o .

Selon une autre caractéristique de l'invention, le signal image de mesure du circuit de compensation est injecté dans un système de traitement électronique délivrant un ordre de déclenchement à une bobine de commande d'un disjoncteur lorsque le signal image dépasse un seuil prédéterminé, l'alimentation du système de traitement s'effectuant au moyen de la tension U2 non compensée prélevée aux bornes de la résistance de charge R2.According to another characteristic of the invention, the image signal for measuring the compensation circuit is injected into an electronic processing system delivering a tripping order to a control coil of a circuit breaker when the image signal exceeds a predetermined threshold, l 'supply to the treatment system by means of the uncompensated voltage U 2 taken from the terminals of the load resistor R 2 .

D'autres avantages ressortiront plus clairement de l'exposé qui va suivre de divers modes de réalisation de l'invention, donnés à titre d'exemples non limitatifs et représentés aux dessins annexés, dans lesquels :

  • la figure 1 est une vue schématique d'un capteur de courant hybride à tore selon l'invention ;
  • la figure 2 illustre deux courbes représentatives du module (en traits forts) et du déphasage (en traits pointillés) du courant de sortie 12, en fonction de la constante de temps secondaire t2 du capteur selon la fig. 1, la fréquence f du courant primaire l1 étant de 50 Hz ;
  • les figures 3 et 4 sont deux variantes de réalisation du capteur de courant selon la fig. 1 ;
  • la figure 5 représente le schéma équivalent d'un capteur hybride selon les fig. 2 à 4, équipé d'un circuit de compensation de fréquence ;
  • la figure 6 est une vue partielle de la fig. 5 et montre une variante du circuit de compensation de fréquence ;
  • la figure 7 montre les diagrammes représentatifs des amplitudes des tensions de sortie U2 et Uc du capteur respectivement avant et après la compensation, en fonction de la fréquence f du courant primaire l1 à mesurer ;
  • la figure 8 représente l'application d'un capteur hybride compensé selon l'invention à un dispositif électronique de commande d'un disjoncteur de protection.
Other advantages will emerge more clearly from the description which follows of various embodiments of the invention, given by way of nonlimiting examples and represented in the appended drawings, in which:
  • Figure 1 is a schematic view of a hybrid toroid current sensor according to the invention;
  • FIG. 2 illustrates two curves representative of the module (in strong lines) and of the phase shift (in dotted lines) of the output current 1 2 , as a function of the secondary time constant t 2 of the sensor according to FIG. 1, the frequency f of the primary current l 1 being 50 Hz;
  • Figures 3 and 4 are two alternative embodiments of the current sensor according to FIG. 1;
  • FIG. 5 represents the equivalent diagram of a hybrid sensor according to FIGS. 2 to 4, equipped with a frequency compensation circuit;
  • FIG. 6 is a partial view of FIG. 5 and shows a variant of the frequency compensation circuit;
  • FIG. 7 shows the diagrams representative of the amplitudes of the output voltages U 2 and U c of the sensor respectively before and after the compensation, as a function of the frequency f of the primary current l 1 to be measured;
  • FIG. 8 represents the application of a compensated hybrid sensor according to the invention to an electronic device for controlling a protective circuit breaker.

Sur la figure 1, le capteur de courant hybride 10 comporte un circuit magnétique CM en forme de tore doté d'un ou de plusieurs entrefers 12 de longueur totale e. Le circuit magnétique CM est traversé par une ligne 14 d'un réseau d'alimentation en courant alternatif, la ligne 14 jouant le rôle d'enroulement primaire parcouru par un courant l1 à contrôler. Un enroulement secondaire 16 est bobiné sur le tore et comprend n spires de résistance ohmique Rl. Une résistance de charge R2 est connectée aux bornes de sortie de l'enroulement secondaire. La constante de temps secondaire t2 du capteur hybride est définie par la relation n2/Re(Rl + R2), Re étant la réluctance totale du circuit magnétique CM.In FIG. 1, the hybrid current sensor 10 comprises a magnetic circuit CM in the form of a torus provided with one or more air gaps 12 of total length e. The magnetic circuit CM is crossed by a line 14 of an alternating current supply network, the line 14 playing the role of primary winding traversed by a current l 1 to be checked. A secondary winding 16 is wound on the toroid and comprises n turns of ohmic resistance R l . A load resistor R 2 is connected to the output terminals of the secondary winding. The secondary time constant t 2 of the hybrid sensor is defined by the relation n 2 / Re (R l + R2), Re being the total reluctance of the magnetic circuit CM.

L'enroulement secondaire 16 délivre un courant de sortie 12 représentant une grandeur vectorielle dont le module et le déphasage ϕ par rapport au courant primaire l1 sont illustrés par les diagrammes de la figure 2 en fonction de la constante de temps secondaire t2 et pour une fréquence f donnée du courant primaire l1. Le module exprimé par le rapport nl2/l1 varie entre 0 et 1 lorsque la constante de temps t2 croît. Pour des constantes de temps t2 supérieures à 100 millisecondes, le capteur est un transformateur de courant conventionnel. Pour des constantes de temps t2 inférieures à 10 microsecondes, le capteur est du type amagnétique. Le capteur hybride occupe la zone intermédiaire. La section de l'enroulement secondaire d'un capteur inductif étant proportionnelle au produit nl2' on remarque sur la figure 2 que c'est le transformateur de courant où nl2 est voisin de l1, qui exige le volume de bobinage le plus important et qui est donc le plus coûteux.The secondary winding 16 delivers an output current 1 2 representing a vector quantity whose module and phase shift ϕ relative to the primary current l 1 are illustrated by the diagrams of FIG. 2 as a function of the secondary time constant t 2 and for a given frequency f of the primary current l 1 . The modulus expressed by the ratio nl 2 / l 1 varies between 0 and 1 when the time constant t 2 increases. For time constants t 2 greater than 100 milliseconds, the sensor is a conventional current transformer. For time constants t 2 of less than 10 microseconds, the sensor is of the non-magnetic type. The hybrid sensor occupies the intermediate zone. The section of the secondary winding of an inductive sensor being proportional to the product nl 2 ′ it can be seen in FIG. 2 that it is the current transformer where nl 2 is close to l 1 , which requires the most winding volume important and which is therefore the most expensive.

Un capteur hybride dont la constante de temps t2 est comprise entre 10 microsecondes et 100 millisecondes, nécessite un enroulement secondaire considérablement réduit par rapport à un transformateur de courant équivalent. Ou encore dans un encombrement donné, entre un transformateur de courant conventionnel et un capteur hybride d'intensités nominales primaires identiques, c'est ce dernier qui est le siège de l'échauffement le plus réduit. Il suffira par conséquent de choisir les valeurs de la résistance de charge R2, de la section S du circuit magnétique CM et de la longueur de l'entrefer e pour déterminer la valeur de t2. Des essais ont montré que la longueur totale de l'entrefer e devait être comprise entre 0,5 et 20 millimètres, et la résistance de charge R2 était comprise entre 10 et 1 000 Ohms selon l'intensité du courant nominal l1 à contrôler circulant dans la ligne 14.A hybrid sensor whose time constant t 2 is between 10 microseconds and 100 milliseconds, requires a considerably reduced secondary winding compared to an equivalent current transformer. Or even in a given space, between a conventional current transformer and a hybrid sensor of identical primary nominal intensities, it is the latter which is the seat of the most reduced temperature rise. It will therefore suffice to choose the values of the load resistance R 2 , of the section S of the magnetic circuit CM and of the length of the air gap e to determine the value of t 2 . Tests have shown that the total length of the air gap e must be between 0.5 and 20 millimeters, and the load resistance R 2 is between 10 and 1000 Ohms depending on the intensity of the nominal current l 1 to be checked. running in line 14.

Sur la figure 3, le tore à un entrefer 12 de la fig. 1 a été remplacé par un circuit magnétique CM rectangulaire à deux entrefers 12a, 12b, comprenant deux parties élémentaires en U situées en regard l'une de l'autre, de manière à confiner une fenêtre traversée par la ligne 14. Un enroulement secondaire 16 unique est bobiné sur le circuit magnétique CM.In FIG. 3, the torus has an air gap 12 in FIG. 1 has been replaced by a rectangular magnetic circuit CM with two air gaps 12a, 12b, comprising two elementary U-shaped parts located opposite one another, so as to confine a window crossed by the line 14. A secondary winding 16 single is wound on the magnetic circuit CM.

Selon la figure 4, l'enroulement secondaire est formé par deux bobines 16a, 16b connectées en série ou en parallèle, le reste étant identique au capteur de la fig. 3. La position relative des bobines 16a, 16b par rapport aux entrefers peut être quelconque. Les caractéristiques du capteur hybride 10 selon les figures 1 à 3 dépendent néanmoins de la variation de fréquence du courant l1 à mesurer. L'amplitude et la phase de la tension de sortie U2 aux bornes de l'enroulement secondaire 16 varient en effet avec la fréquence. C'est pourquoi un circuit de compensation 18 (fig. 5) de fréquence est associé au capteur hybride.According to FIG. 4, the secondary winding is formed by two coils 16a, 16b connected in series or in parallel, the rest being identical to the sensor of FIG. 3. The relative position of the coils 16a, 16b with respect to the air gaps can be arbitrary. The characteristics of the hybrid sensor 10 according to FIGS. 1 to 3 nevertheless depend on the frequency variation of the current l 1 to be measured. The amplitude and the phase of the output voltage U 2 at the terminals of the secondary winding 16 indeed vary with the frequency. This is why a frequency compensation circuit 18 (FIG. 5) is associated with the hybrid sensor.

Le circuit de compensation de fréquence 18 (fig. 5) est formé par un circuit série RC branché en parallèle aux bornes de la résistance de charge R2. Le signal image du courant l1 à mesurer est la tension Uc aux bornes du condensateur C. Les valeurs de R et C du circuit 18 sont définies par la relation suivante :

Figure imgb0001
où fo est la fréquence centrale de compensation (55 Hz par exemple).The frequency compensation circuit 18 (fig. 5) is formed by a series circuit RC connected in parallel to the terminals of the load resistor R 2 . The image signal of the current l 1 to be measured is the voltage U c across the capacitor C. The values of R and C of circuit 18 are defined by the following relation:
Figure imgb0001
 where f o is the central compensation frequency (55 Hz for example).

Sur la figure 6, le circuit de compensation 18 est constitué par un circuit série à inductance Let résistance R, branché en parallèle aux bornes de R2, le signal image de mesure du courant l1 étant dans ce cas la tension UR aux bornes de la résistance R.In FIG. 6, the compensation circuit 18 is constituted by a series circuit with an inductance Let resistance R, connected in parallel to the terminals of R 2 , the image signal for measuring the current l 1 in this case being the voltage U R at the terminals of resistance R.

La figure 7 compare les amplitudes des tensions de sorties U2 et Uc avant et après la compensation en fonction de la fréquence f du courant à mesurer, les valeurs de la constante de temps t2 et de l'intensité du courant 1, étant données. On remarque que l'amplitude de la tension image Uc est sensiblement constante lorsque la fréquence f du courant l1 est comprise dans une fourchette prédéterminée autour de la fréquence centrale fo de compensation. Le courant l1 à mesurer et la tension Uc sont en phase lorsque la fréquence du courant l1 est égale à la fréquence fo centrale.FIG. 7 compares the amplitudes of the output voltages U 2 and U c before and after the compensation as a function of the frequency f of the current to be measured, the values of the time constant t 2 and of the intensity of the current 1, being data. It will be noted that the amplitude of the image voltage U c is substantially constant when the frequency f of the current l 1 is within a predetermined range around the central frequency f o of compensation. The current l 1 to be measured and the voltage Uc are in phase when the frequency of the current l 1 is equal to the central frequency f o .

La figure 8 représente l'application d'un capteur hybride compensé décrit en référence à la fig. 5, et délivrant un signal secondaire combiné de mesure et d'alimentation à un dispositif de commande électronique ou déclencheur statique d'un disjoncteur à propre courant dont l'un des contacts 20 est inséré dans la ligne 14. Le signal image de mesure Uc du circuit de compensation 18 est injecté dans un système de traitement 22 électronique par l'intermédiaire d'un premier conducteur de liaison 24. La tension U2 non compensée de l'enroulement secondaire 16 sera utilisée avantageusement pour l'alimentation du système de traitement 22 grâce à un deuxième conducteur 26 de liaison. Lors de l'apparition d'un défaut de surcharge ou de court-circuit sur la ligne 14, la sortie du système de traitement 22 délivre un ordre de déclenchement à une bobine 28 de commande qui provoque d'une manière classique le déverrouillage du mécanisme 30 et l'ouverture des contacts 20 du disjoncteur de protection.FIG. 8 represents the application of a compensated hybrid sensor described with reference to FIG. 5, and delivering a combined secondary measurement and supply signal to an electronic control device or static trip device of a circuit breaker with its own current, one of the contacts 20 of which is inserted in line 14. The measurement image signal U c of the compensation circuit 18 is injected into an electronic processing system 22 via a first connecting conductor 24. The uncompensated voltage U 2 of the secondary winding 16 will be advantageously used for supplying the treatment 22 thanks to a second connecting conductor 26. When an overload or short-circuit fault occurs on line 14, the output of the processing system 22 delivers a tripping order to a control coil 28 which conventionally causes the mechanism to be unlocked. 30 and the opening of the contacts 20 of the protective circuit breaker.

Claims (10)

1. Current sensor (10) for electronically measuring and/or protective equipment intended to control the current in a line (14) of an electrical energy supply system, said inductive sensor coupled with the line and comprising :
- a magnetic circuit or core CM enclosing the line (14) and equipped with at least one amagnetic air-gap (12, 12a, 12b) of predetermined length e, said circuit having a reluctance Re,
- a secondary winding (16, 16a, 16b) wound about the magnetic circuit CM and having a number of winding turns n and an ohmic resistance R1,
- a load resistance connected electrically to the output terminals of the secondary winding and having an ohmic resistance R2, characterized in that the inductive sensor (10) is of hybrid type of which the secondary time constant t2 is defined by the relation n2/Re(Rl + R2) having a value comprised between 10 microseconds and 100 milliseconds.
2. Current sensor according to claim 1, characterized in that the total length e of one/or several amagnetic air-gaps (12, 12a, 12b) of core CM is advantageously comprised between 0.5 and 20 millimeters, and the load resistance R2 value in the neighbourhood of 10 to 1 000 ohms.
3. Current sensor according to claim 1 or 2, characterized in that the secondary winding (16, 16a, 16b) of the hybrid sensor (10) cooperates with a frequency compensating circuit (18) connected to the load resistance R2 terminals, and generating a measuring image signal of which the amplitude is almost constant when the primary current 11 frequency f flowing in the line (14) is comprised in a predetermined bracket about a compensation central frequency fo.
4. Current sensor according to claim 3, characterized in that said frequency compensating circuit (18) comprises a phase-shifter system of phasing the measuring image signal with the primary current l1 to control when the frequency of this last one corresponds to the central frequency fo.
5. Current sensor according to claim 3 or 4, characterized in that the frequency compensating circuit (18) consists of a series circuit comprising a resistance R and a capacitor C, connected in parallel to the load resistance R2 terminals as the image signal of current I, measurement is represented by the voltage Ue between the capacitor C terminals.
6. Current sensor according to claim 5, characterized in that the values of the series circuit resistance R and capacitor C are determined by the time constant RC defined by the relation 1/(2πf0)2t2, fo being the compensation central frequency and t2 the secondary time constant of the hybrid sensor (10).
7. Current sensor according to claim 3 or 4, characterized in that the frequency compensating circuit (18) comprises a series circuit with inductance L and resistance R, connected in parallel to the load resistance R2 terminals, the image signal of current l1 measurement being the voltage UR between the resistance R terminals.
8. Current sensor according to any of the former claims 1 to 7, characterized in that the core CM material is ferromagnetic or sintered.
9. Current sensor according to claim 8, characterized in that the image signal of the compensating circuit (18) measurement is injected into an electronic processing system (22) generating a tripping order to a circuit breaker operation coil (28) when the image signal exceeds a predetermined threshold, the processing system (22) supply being carried out by means of the non compensated voltage U2 taken between the load resistance R2 terminals.
10. Current sensor according to any of the former claims 1 to 9, characterized in that the hybrid sensor (10) core CM comprises two U-shaped elementary portions separated from each other by two air-gaps (12a, 12b) disposed on both sides of the line (14) acting as primary winding.
EP19820401529 1981-08-26 1982-08-13 Hybrid compensated current transformer Expired EP0074297B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8118416 1981-08-26
FR8116416A FR2512264A1 (en) 1981-08-26 1981-08-26 COMPENSATED HYBRID CURRENT SENSOR

Publications (3)

Publication Number Publication Date
EP0074297A1 EP0074297A1 (en) 1983-03-16
EP0074297B1 true EP0074297B1 (en) 1985-11-21
EP0074297B2 EP0074297B2 (en) 1988-12-07

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ID=9261728

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Application Number Title Priority Date Filing Date
EP19820401529 Expired EP0074297B2 (en) 1981-08-26 1982-08-13 Hybrid compensated current transformer

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EP (1) EP0074297B2 (en)
JP (1) JPS5895266A (en)
CA (1) CA1203284A (en)
DE (1) DE3267597D1 (en)
FR (1) FR2512264A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5495169A (en) * 1984-10-12 1996-02-27 Smith; Dayle Clamp-on current sensor
FR2603992B1 (en) * 1986-09-16 1988-10-28 Alsthom DEVICE FOR THE DIGITAL ACQUISITION OF AN ALTERNATIVE ELECTRIC CURRENT FROM A CURRENT TRANSFORMER WITH SATURABLE MAGNETIC CORE
DE3701779A1 (en) * 1987-02-13 1988-08-04 Budapesti Mueszaki Egyetem AS A CURRENT TRANSFORMER, LINEAR TRANSMITTER
JPH01122735A (en) * 1987-11-06 1989-05-16 Nissan Motor Co Ltd Constant speed running device
FR2752996B1 (en) * 1996-09-05 1998-10-02 Schneider Electric Sa CURRENT TRANSFORMER AND PROTECTION RELAY COMPRISING SUCH A TRANSFORMER

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR514999A (en) * 1916-01-10 1921-03-22 Siemens Schuckertwerke Gmbh Current transformer whose load includes a capacitor in order to compensate for the wattage current
DE535000C (en) * 1928-08-11 1931-10-05 Elek Zitaets Act Ges Vorm W La Resonance circuit
FR833139A (en) * 1937-03-02 1938-10-12 Siemens Ag Ring-core current transformer for measuring high frequency currents
FR1142618A (en) * 1956-02-09 1957-09-20 Telemecanique Electrique Method and device for measuring high intensities
CH350710A (en) * 1956-11-09 1960-12-15 Bbc Brown Boveri & Cie Current transformer system for high voltage systems
DE1281545B (en) * 1963-05-29 1968-10-31 Siemens Ag Iron core converter with air gap for current measurement

Also Published As

Publication number Publication date
CA1203284A (en) 1986-04-15
JPH0447271B2 (en) 1992-08-03
DE3267597D1 (en) 1986-01-02
EP0074297A1 (en) 1983-03-16
FR2512264B1 (en) 1983-10-28
EP0074297B2 (en) 1988-12-07
JPS5895266A (en) 1983-06-06
FR2512264A1 (en) 1983-03-04

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