WO1994023306A1 - Dispositif optique permettant de mesurer un courant electrique avec des lignes de transmission entrelacees - Google Patents

Dispositif optique permettant de mesurer un courant electrique avec des lignes de transmission entrelacees Download PDF

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Publication number
WO1994023306A1
WO1994023306A1 PCT/DE1994/000251 DE9400251W WO9423306A1 WO 1994023306 A1 WO1994023306 A1 WO 1994023306A1 DE 9400251 W DE9400251 W DE 9400251W WO 9423306 A1 WO9423306 A1 WO 9423306A1
Authority
WO
WIPO (PCT)
Prior art keywords
transmission path
light
faraday
transmission
arrangement according
Prior art date
Application number
PCT/DE1994/000251
Other languages
German (de)
English (en)
Inventor
Thomas Bosselmann
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to DE9421402U priority Critical patent/DE9421402U1/de
Publication of WO1994023306A1 publication Critical patent/WO1994023306A1/fr

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Classifications

    • 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
    • G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
    • G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
    • G01R15/246—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect based on the Faraday, i.e. linear magneto-optic, effect

Definitions

  • Optical measuring arrangement for measuring an electrical current with intertwined transmission lines
  • the invention relates to an arrangement for measuring an electrical current in a current conductor according to the preamble of claim 1, which is known for example from WO 91/01501.
  • Optical measuring arrangements for measuring an electrical current in a current conductor using the Faraday effect are known, which are also referred to as magneto-optical current transformers.
  • the Faraday effect is the rotation of the plane of polarization of linearly polarized light as a function of a magnetic field.
  • the angle of rotation is proportional to the path integral over the magnetic field along the path covered by the light with the Verdet constant as the proportion constant.
  • the Verdet constant depends on the material in which the light runs and on the wavelength of the light.
  • a Faraday element made of a material having the Faraday effect, such as glass is now assigned to the current conductor.
  • the Faraday element can be constructed from one or more solid bodies with which a closed light path can be formed around the current conductor to suppress external interference fields (EP-B 0 088 419 or US 5 008 611).
  • an optical fiber can be provided as the Faraday element, which surrounds the current conductor in the form of a measuring winding.
  • Linearly polarized light is sent through a transmission unit through the Faraday element.
  • the magnetic field generated by the electric current causes the plane of polarization of the light in the Faraday element to rotate, which is generated by an evaluation unit can be evaluated as a measure of the strength of the magnetic field and thus of the strength of the electrical current. If the Faraday element represents a quasi-closed path for the linearly polarized light around the current conductor, the polarization rotation angle is in good approximation directly proportional to the current strength.
  • Two types of such magneto-optical current transformers are known, namely the transmission type and the reflection type.
  • the transmission type the light is coupled into one end of the Faraday element and then coupled out again at the other end, so that the light passes through the Faraday element only once.
  • the reflection type the other end of the Faraday element is mirrored, so that the light coupled in at the first end is reflected at this other mirrored end, the Faraday element passes through a second time in the opposite direction and is coupled out again at the first end. Because of the non-reciprocity of the Faraday effect, the plane of polarization of the light is rotated again in the same direction in the same direction during the reverse pass. The angle of rotation is thus twice as large for the same Faraday element as for the transmission type. A beam expensive is provided to separate the coupled-in and coupled-out light.
  • the measured values of the polarization rotation can be falsified by external interference induction fields due to the Faraday effect.
  • interference fields can occur, for example, in the case of multiphase line branches through the adjacent current conductors.
  • the first end of the fiber, which is provided for coupling the light in and out, and the mirrored, other end are arranged in close proximity to one another. An almost closed light path is thus obtained in the fiber.
  • the invention is based on the object of specifying an arrangement for measuring an electrical current in a conductor using the Faraday effect, which can be designed as a reflection or transmission type and in which the measurement errors in the transmission links are further reduced can.
  • FIG. 1 shows an embodiment of an arrangement for measuring an electric current using the Faraday effect of the reflection type
  • FIG. 2 shows an exemplary embodiment of such a measuring arrangement of the transmission type
  • FIG. 1 and 2 are a current conductor with 2, a light waveguide with 3 and a transmission and evaluation unit with 4.
  • the optical waveguide 3 preferably concentrically surrounds the current conductor 2 in at least one measurement winding 3C.
  • several measuring windings 3C are connected in series as a fiber coil.
  • FIG. 2 shows an embodiment with only one measuring turn 3C.
  • a first end 3A of the optical waveguide 3 is connected to the transmitting and evaluating unit 4, and the second end 3E is designed to be light-reflecting, preferably by arranging a mirror 30 at this end 3E or by mirroring the end 3E.
  • the first transmission path 3B of the optical waveguide 3 lying between the first end 3A and the measuring winding 3C and the second transmission path 3D lying between the other end 3E and the measuring winding 3C are now interwoven with one another such that at least one crossing point Pl for their light paths is formed.
  • N crossing points P1, P2,..., PN are preferably provided with N> 1. This measure creates quasi-closed light loops through which no electrical current flows and in which therefore due to of the Flooding Law no Faraday rotation of the polarization plane of the 3B and 3D propagating linear polarized light can take place. Interference magnetic fields can be suppressed in this way.
  • the light loops are preferably chosen to be as small as possible by adapting the number N of the crossing points P1 to PN to the lengths of the transmission paths 3B and 3D.
  • the other end 3E of the transmission link 3D is preferably arranged in the immediate vicinity of the transmission link 3B and generally also to the first end 3A.
  • a further quasi-closed light loop is thus formed between the crossing point PN closest to the end 3E along the light paths and the end 3E.
  • the interweaving of the two transmission links 3B and 3D can also be carried out in an arrangement of the transmission type in which the other end 3E of the optical waveguide 3 is not mirrored, but is optically coupled to a corresponding connection of the transmitting and evaluating unit 4 .
  • Such a transmission type arrangement is shown in FIG. 2 shown.
  • a further light loop can be formed by arranging the end of a transmission path 3B or 3D in the immediate vicinity of the other transmission path 3B or 3D.
  • the transmission and evaluation unit 4 preferably contains a light source 41, an optoelectric converter 43 and evaluation electronics 44.
  • a beam splitting device 42 is additionally provided between the first transmission path 3B and the light source 41 and the converter 43 for separate on and off couple the linearly polarized light coming from the light source 41 and the light that has passed through the measuring winding 3C with a rotated plane of polarization.
  • the linearly polarized light from the light source 41 is coupled directly into the first transmission path 3B, passes through the measurement winding 3C provided as a Farag element and is coupled directly into the converter 43 from the second transmission path 3D.
  • the light source 41 preferably contains a laser diode with a corresponding electrical supply.
  • the optoelectric converter 43 preferably comprises a Wollaston prism 43A and two corresponding receiving photodiodes 43B and 43C for converting the ordinary or extraordinarily borrowed light beam coming from the Wollaston prism.
  • Receiving photodiodes 43B and 43C are preferably connected to the evaluation electronics 44 via assigned amplifiers 43D and 43E and evaluated there, for example, as a differential measurement signal.
  • the measures according to the invention can also be used advantageously in other optical measuring arrangements for current measurement.
  • a Faraday element assigned to the current conductor 2 generally bodies made of the materials having the Faraday effect, for example glass, can be provided.
  • a single, coherent Faraday body or an arrangement of individual, optically connected Faraday sub-bodies is preferably provided such that a closed light path is formed around the current conductor 2 with the Faraday body or the arrangement of the sub-bodies.
  • Such a Faraday body or such a Faraday measuring arrangement is known for example from EP-B-0 088 419 or US 5 008 611.
  • the transmission links 3B and 3D are then formed with separate optical waveguides, preferably made of the same material, via which linearly polarized light can be transmitted and which are optically coupled to the Fara day element.
  • Such separate, polarization-maintaining optical waveguides as transmission links can also be provided in embodiments with one or more measurement windings 3C as a Faraday element.
  • a polarization-maintaining optical waveguide Single-mode optical fibers such as HiBi (high birefringence) fibers or polarization-neutral LoBi (low birefringence) fibers are used.
  • the transmission links 3B and 3D have an intrinsic birefringence that is not negligible compared to the Faraday rotation caused by the current, a measurement error can also occur due to interference magnetic fields even with a closed light loop.
  • an even number of light loops formed with the two transmission links is therefore provided.
  • the opposite, alternating sense of rotation of the light in each of the light loops additionally achieves a compensation effect for the additional measurement errors that can occur in the transmission links due to intrinsic linear birefringence.
  • An even number of light loops can be achieved by choosing an odd number N ⁇ 3 from crossing points Pl to PN or by an even number N> 2 from crossing points Pl to PN selects and at the same time arranges one end facing away from the Faraday element of one of the two transmission links in spatial proximity to the other transmission link, so that an additional, quasi-closed light loop is thus formed.

Abstract

L'invention concerne un dispositif permettant de mesurer un courant électrique en se servant de l'effet Faraday, qui comprend un guide d'ondes lumineuses (3) qui est guidé dans au moins une spire de mesure (3C) autour du conducteur (2) parcouru par le courant, et une unité d'émission et d'évaluation (4) servant à injecter la lumière polarisée linéairement dans le guide d'ondes lumineuses (3) et à l'en faire sortir. Selon l'invention, les deux sections de transport du courant (3B et 3D) sont entrelacées entre les extrémités (3A et 3E) du guide d'ondes lumineuses (3) et la spire de mesure (3C), de manière à ce que leurs chemins optiques se croisent au moins en un point d'intersection (P1), ce qui permet d'éviter l'apparition d'erreurs de mesure dues à des champs magnétiques parasites. L'invention prévoit de préférence une pluralité de points d'intersection et un nombre correspondant de petites boucles optiques afin de supprimer les valeurs mesurées faussées, dues à la biréfringence linéaire intrinsèque.
PCT/DE1994/000251 1993-04-06 1994-03-10 Dispositif optique permettant de mesurer un courant electrique avec des lignes de transmission entrelacees WO1994023306A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE9421402U DE9421402U1 (de) 1993-04-06 1994-03-10 Optische Meßanordnung zum Messen eines elektrischen Stromes mit verflochtenen Übertragungsleitungen

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19934311328 DE4311328A1 (de) 1993-04-06 1993-04-06 Optische Meßanordnung zum Messen eines elektrischen Stromes mit verflochtenen Übertragungsleitungen
DEP4311328.1 1993-04-06

Publications (1)

Publication Number Publication Date
WO1994023306A1 true WO1994023306A1 (fr) 1994-10-13

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DE (2) DE4311328A1 (fr)
WO (1) WO1994023306A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996038735A1 (fr) * 1995-05-31 1996-12-05 The University Of Sydney Transducteur a fibres optiques

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19621654A1 (de) * 1996-05-30 1997-12-04 Abb Research Ltd Magneto-optischer Stromsensor
IT1288763B1 (it) * 1996-10-17 1998-09-24 Umberto Sardo Apparecchio a circuito ottico ritracciante per la misura di grandezze fisiche insensibile a perturbazioni ambientali

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0088419A1 (fr) * 1982-03-08 1983-09-14 Hitachi, Ltd. Dispositif pour mesurer optiquement un courant
EP0108012A1 (fr) * 1982-10-28 1984-05-09 Commissariat à l'Energie Atomique Dispositif de mesure d'intensité électrique à effet Faraday
EP0290780A1 (fr) * 1987-04-10 1988-11-17 Alsthom Dispositif de mesure d'intensité d'un courant électrique par effet Faraday mis en oeuvre au sein d'un interféromètre de Sagnac
WO1991001501A1 (fr) * 1989-07-19 1991-02-07 Mwb Messwandler-Bau Ag Dispositif a fibres optiques pour mesurer l'intensite d'un courant electrique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0088419A1 (fr) * 1982-03-08 1983-09-14 Hitachi, Ltd. Dispositif pour mesurer optiquement un courant
EP0108012A1 (fr) * 1982-10-28 1984-05-09 Commissariat à l'Energie Atomique Dispositif de mesure d'intensité électrique à effet Faraday
EP0290780A1 (fr) * 1987-04-10 1988-11-17 Alsthom Dispositif de mesure d'intensité d'un courant électrique par effet Faraday mis en oeuvre au sein d'un interféromètre de Sagnac
WO1991001501A1 (fr) * 1989-07-19 1991-02-07 Mwb Messwandler-Bau Ag Dispositif a fibres optiques pour mesurer l'intensite d'un courant electrique

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996038735A1 (fr) * 1995-05-31 1996-12-05 The University Of Sydney Transducteur a fibres optiques
US6034522A (en) * 1995-05-31 2000-03-07 The University Of Sydney Fibre optic transducer incorporating an extraneous factor compensation referencing system

Also Published As

Publication number Publication date
DE9421402U1 (de) 1995-10-19
DE4311328A1 (de) 1994-10-13

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