WO1999044070A1 - Device for measuring a current by means of a fibre-optic sagnac interferometer - Google Patents

Device for measuring a current by means of a fibre-optic sagnac interferometer Download PDF

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Publication number
WO1999044070A1
WO1999044070A1 PCT/EP1999/000549 EP9900549W WO9944070A1 WO 1999044070 A1 WO1999044070 A1 WO 1999044070A1 EP 9900549 W EP9900549 W EP 9900549W WO 9944070 A1 WO9944070 A1 WO 9944070A1
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Prior art keywords
current
fiber
current measuring
coil
measuring
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PCT/EP1999/000549
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German (de)
French (fr)
Inventor
Eberhard Handrich
Manfred Kemmler
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Litef Gmbh
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Priority to EP99904822A priority Critical patent/EP1058853A1/en
Publication of WO1999044070A1 publication Critical patent/WO1999044070A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/58—Turn-sensitive devices without moving masses
    • G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
    • G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
    • 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

  • the invention relates to a device for current measurement according to the preamble of claim 1, intended in particular for current measurement in high-voltage distributors and networks.
  • the measurement of large currents in the range of, for example, 1 kA to 65 kA with a center of gravity measuring range of about 10 kA is a technical problem if the bandwidth of the measuring frequency is to range from the DC range to, for example, 1 kHz, with a main load in the range of Mains frequency of 50 Hz.
  • the measurement signal can thus be downmixed to the differential frequency (fi - f2) for a technically more controllable synchronous demodulation.
  • Difficulties, in particular inaccuracies in the measurement result with this known type of current measurement with direct signal evaluation (open loop technology) result from the fact that nonlinearities, in particular considerable changes in the scale factor of the Sagnac interferometer, are not taken into account and that the dynamic range, the possible current measuring range is clearly limited.
  • the invention is therefore based on the object of providing a current measuring device of a high accuracy class, in particular for a comparatively wide frequency range and a large current range, with a measurement resolution of approximately 0.1% to at most 1%. - 2 -
  • the invention provides, according to the definition of patent claim 1, a device for current measurement by means of a fiber-optic Sagnac interferometer, in whose light path, which is penetrated by two opposing partial light beams created by beam splitting of a light beam originating from a light source, a fiber-optic one Current measuring coil is used, which is penetrated by the current to be measured or a conductor carrying a proportional proportion of current, and according to the invention is characterized in that the structure of the fiber optic Sagnac interferometer corresponds to a fiber gyroscope with a closed control loop, in which the current measuring coil at least the sensor coil of the gyro partially replaced.
  • the known structure of a fiber-optic gyroscope with digital reset comprises a light source 1, the light of which reaches a fiber path via a first beam splitter 2, a polarizer 3, and a main beam splitter 4, from whose two outputs the two partial lights formed - rays into the opposite ends 5 ⁇ , 52 > so in the opposite direction in a closed light path 5, are irradiated.
  • the closed light path 5 exists in the case of use as a rotation rate sensor.
  • phase modulator 10 is provided at one end of the closed light path, via which the operating point is set on the one hand and the rotation rate is reset or, in the present case, the current value is reset (will be explained in more detail below).
  • the two opposing light beams are reunited after passing through the light path 5 in the main beam splitter and interfere with one another.
  • the returning light beam passes via the polarizer 3 and the first beam splitter 2 to a photodetector 11 with a downstream filter and preamplifier, which feeds a demodulator 12 on the one hand and a synchronous demodulator 13 on the other hand, the reference frequency of which comes from a reference generator 16, which is a on the transit time of the light through the light path 5 tuned signal with randomly distributed Phasensprün- gene of n • ⁇ / 4 supplies with which a signal adder 19, and an AGC amplifier 18 modulates the phase of light at the phase modulator 10 degrees.
  • the phase jumps for odd n provide the reference signal for the synchronous demodulator 13.
  • phase jumps of a reference generator 16 for even n provide the reference signal for the demodulator 12, the output signal of which controls the gain of the AGC amplifier 18 via a filter 17 such that the output signal of the demodulator 12 is zero. This regulates the scale factor of the phase modulator 10 and thus also the scale factor of the output signal.
  • the measuring principle is based on the Faraday effect. The rotation caused by the current through conductor 8 - 4 -
  • the current measuring coil 7, designed as a special fiber coil, is preferably made of a single-mode fiber with a length L, care being taken to ensure that circularly polarized light flows at least preferably in the current measuring coil 7, in order to ensure a maximum effect of the Faraday effect.
  • the sensor coil 6, on the other hand, is shortened by the length L (e.g. 100m-L); it is wound from PM fiber.
  • the resolution is limited to 0.036% of the range due to noise.
  • the current measuring range can be adjusted by the length L of the current measuring coil 7.
  • the "conversion" to the ammeter according to the invention is effected in such a way that two fiber ends of the light path 5 are preferably led out from the center of the sensor coil 6 to minimize the vibration-shock effect, the ⁇ / 4-phase shifter elements 9, 92 and the current measuring coil 7 can be provided inside or outside the housing of the fiber gyroscope.

Abstract

The invention aims to allow the accurate, non-contacting, preferably digital measurement of strong currents, especially in high-voltage distributors and networks. To this end a fibre-optic gyroscope with a closed control loop is used, in which a current measuring coil (7) at least partly replaces the actual sensor coil (6). The measurement principle is based on the Faraday effect. The current measuring device can be used without difficulty for measuring the current in the above kind of supply installation.

Description

Einrichtung zur Strommessung mittels eines faseroptischen Device for measuring current using a fiber optic
Sagnac-InterferometersSagnac interferometer
Die Erfindung betrifft eine Einrichtung zur Strommessung nach dem Ober- begriff des Patentanspruchs 1 , bestimmt insbesondere für die Strommessung in Hochspannungs-Verteilern und -Netzen.The invention relates to a device for current measurement according to the preamble of claim 1, intended in particular for current measurement in high-voltage distributors and networks.
Die Messung von großen Strömen im Bereich von beispielsweise 1 kA bis 65 kA mit einem Schwerpunktme-ßbereich von etwa 10 kA stellt ein technisches Problem dar, wenn die Bandbreite der Meßfrequenz vom DC-Bereich bis beispielsweise 1 kHz reichen soll, mit Hauptlast im Bereich der Netzfrequenz von 50 Hz.The measurement of large currents in the range of, for example, 1 kA to 65 kA with a center of gravity measuring range of about 10 kA is a technical problem if the bandwidth of the measuring frequency is to range from the DC range to, for example, 1 kHz, with a main load in the range of Mains frequency of 50 Hz.
Aus der Druckschrift EP 0 290 780 AI sowie aus DE 31 32 414 AI ist der Vorschlag bekannt, ein faseroptisches Sagnac-Interferometer mittels des eine nicht-reziproke Phasenverschiebung der gegenläufigen Lichtwellen in einer Meßspule verursachenden Faraday-Effekts zur magneto-optischen Strommessung zu nutzen. Speziell die erstgenannte Druckschrift, die den Ausgangspunkt für die Erfindung bildet, beschreibt zur Gewinnung des Meßsignals ein faseroptisches Interferometer in sogenannter Open-Loop-An- ordnung. Dabei werden zur Erhöhung der Meßempfindlichkeit die gegenläufigen durch Strahlteilung entstandenen Teillichtstrahlen vor Eintritt in die Meßspule mit einer Frequenz f2 und die Lichtquelle wird mit einer etwas davon abweichenden Frequenz fi moduliert. Das Meßsignal läßt sich dadurch für eine technisch besser beherrschbare Synchrondemodulation auf die Differenzfrequenz (fi - f2) heruntermischen. Schwierigkeiten, insbesondere Un- genauigkeiten des Meßergebnisses mit dieser bekannten Art der Strommessung bei direkter Signalauswertung (Open-Loop-Technik) ergeben sich daraus, daß Nichtlinearitäten, insbesondere erhebliche Änderungen des Skalen - faktors des Sagnac-Interferometers nicht berücksichtigt werden und daß der Dynamikbereich, also der mögliche Strommeßbereich deutlich eingeschränkt ist.From document EP 0 290 780 AI and from DE 31 32 414 AI the proposal is known to use a fiber optic Sagnac interferometer by means of a non-reciprocal phase shift of the opposing light waves in a measuring coil Faraday effect for magneto-optical current measurement. In particular, the first-mentioned publication, which forms the starting point for the invention, describes a fiber-optic interferometer in a so-called open-loop arrangement in order to obtain the measurement signal. In order to increase the measuring sensitivity, the opposing partial light beams produced by beam splitting are modulated with a frequency f2 before entering the measuring coil and the light source is modulated with a slightly different frequency fi. The measurement signal can thus be downmixed to the differential frequency (fi - f2) for a technically more controllable synchronous demodulation. Difficulties, in particular inaccuracies in the measurement result with this known type of current measurement with direct signal evaluation (open loop technology) result from the fact that nonlinearities, in particular considerable changes in the scale factor of the Sagnac interferometer, are not taken into account and that the dynamic range, the possible current measuring range is clearly limited.
Der Erfindung damit liegt die Aufgabe zugrunde, eine Strommeßeinrichtung hoher Genauigkeitsklasse insbesondere für einen vergleichsweise weiten Frequenzbereich und einen großen Strombereich zu schaffen mit einer Meß- auflösung von etwa 0, 1% bis höchstens 1%. - 2 -The invention is therefore based on the object of providing a current measuring device of a high accuracy class, in particular for a comparatively wide frequency range and a large current range, with a measurement resolution of approximately 0.1% to at most 1%. - 2 -
Zur Lösung dieser Aufgabe sieht die Erfindung gemäß der Definition des Patentanspruchs 1 eine Einrichtung zur Strommessung mittels eines faseroptischen Sagnac-Interferometers vor, in dessen Lichtweg, der von zwei durch Strahlteilung eines von einer Lichtquelle stammenden Lichtstrahls entstan- denen gegenläufigen Teillichtstrahlen durchsetzt wird, eine faseroptische Strommeßspule eingesetzt ist, die von dem zu messenden Strom oder einem dazu proportionalen Stromanteil führenden Leiter durchsetzt ist, und erfindungsgemäß dadurch gekennzeichnet ist, daß der Aufbau des faseroptischen Sagnac-Interferometers einem Faserkreisel mit geschlossener Regelschleife entspricht, bei dem die Strommeßspule die Sensorspule des Kreisels mindestens teilweise ersetzt.To achieve this object, the invention provides, according to the definition of patent claim 1, a device for current measurement by means of a fiber-optic Sagnac interferometer, in whose light path, which is penetrated by two opposing partial light beams created by beam splitting of a light beam originating from a light source, a fiber-optic one Current measuring coil is used, which is penetrated by the current to be measured or a conductor carrying a proportional proportion of current, and according to the invention is characterized in that the structure of the fiber optic Sagnac interferometer corresponds to a fiber gyroscope with a closed control loop, in which the current measuring coil at least the sensor coil of the gyro partially replaced.
Insbesondere die Verwendung eines Faserkreisels mit digitaler Phasenram- penrückstellung gemäß einer vorteilhaften Ausführungsform der Erfindung bildet damit ein neues Meßprinzip zur berührungslosen bzw. kontaktlosen und hochgenauen Strommessung.In particular, the use of a fiber optic gyro with digital phase ramp resetting according to an advantageous embodiment of the invention thus forms a new measuring principle for contactless or contactless and highly precise current measurement.
Ergänzend sei erwähnt, daß die Ausnutzung des für das Meßprinzig maßgeblichen Faraday- Effekts in umgekehrter Richtung also zur Beeinflussung eines Lichtwegs im Sinne eines Phasenschiebers über eine den Lichtweg umschließende Spule (vgl. FR 2 465 199 B l) oder in Verbindung mit Rotationsmeßeinrichtungen auch zur Bestimmung von Druck, Spannung und Torsion bekannt ist (vgl. US 4 436 422).In addition, it should be mentioned that the use of the Faraday effect, which is decisive for the measuring prince, in the opposite direction, that is, for influencing a light path in the sense of a phase shifter via a coil enclosing the light path (cf. FR 2 465 199 B1) or in connection with rotation measuring devices Determination of pressure, tension and torsion is known (cf. US 4,436,422).
Ein Ausführungsbeispiel der Erfindung wird nachfolgend unter Bezug auf die Zeichnung vorgestellt, deren einzige Figur den Prinzip-Blockschaltbild- aufbau eines Faserkreisels mit digitaler Rückstellung zeigt, dessen (Drehra- ten-)Sensorspule erfindungsgemäß "zweckentfremdet" und als Strommeßspule verwendet bzw. um eine solche Strommeßspule ergänzt ist.An embodiment of the invention is presented below with reference to the drawing, the only figure of which shows the basic block diagram structure of a fiber gyroscope with digital reset, the (rotation rate) sensor coil according to the invention "misused" and used as a current measuring coil or around such Current measuring coil is supplemented.
Der bekannte Aufbau eines faseroptischen Kreisels mit digitaler Rückstellung umfaßt eine Lichtquelle 1 , deren Licht in eine Faserstrecke über einen ersten Strahlteiler 2, einen Polarisator 3 auf einen Hauptstrahlteiler 4 gelangt, von dessen beiden Ausgängen aus die entstandenen beiden Teillicht - strahlen in die entgegengesetzten Enden 5 ι , 52 > also in gegenläufige Richtung in einen geschlossenen Lichtweg 5, eingestrahlt werden. Der geschlossene Lichtweg 5 besteht im Falle der Verwendung als Drehratensensor ins- - 3 -The known structure of a fiber-optic gyroscope with digital reset comprises a light source 1, the light of which reaches a fiber path via a first beam splitter 2, a polarizer 3, and a main beam splitter 4, from whose two outputs the two partial lights formed - rays into the opposite ends 5 ι, 52 > so in the opposite direction in a closed light path 5, are irradiated. The closed light path 5 exists in the case of use as a rotation rate sensor. - 3 -
besondere aus einer polarisationserhaltenden Monomodefaser (PM-Faser) mit einer bestimmten Länge von beispielsweise 100 m, die zu einer Sensorspule 6 gewickelt ist. An einem Ende des geschlossenen Lichtwegs ist ein Phasenmodulator 10 vorgesehen, über den einerseits die Arbeitspunktein- Stellung und andererseits die Drehraten-Rückstellung bzw. im vorliegenden Fall die Stromwertrückstellung erfolgt (wird nachfolgend näher erläutert). Die beiden gegenläufigen Lichtstrahlen werden nach Durchlaufen des Lichtwegs 5 im Hauptstrahlteiler wieder vereinigt und interferieren miteinander. Der zurücklaufende Lichtstrahl gelangt über den Polarisator 3 und den er- sten Strahlteiler 2 auf einen Fotodetektor 1 1 mit nachgeschaltetem Filter und Vorverstärker, der einen Demodulator 12 einerseits und einen Syn- chrondemodulator 13 andererseits speist, deren Referenzfrequenz von einem Referenzgenerator 16 stammt, der ein auf die Durchlaufzeit des Lichts durch den Lichtweg 5 abgestimmtes Signal mit statistisch verteilten Phasensprün- gen von n • λ/4 liefert, mit denen über einen Signaladdierer 19 und einen AGC -Verstärker 18 am Phasenmodulator 10 die Lichtphase moduliert wird. Die Phasensprünge für ungerades n liefern das Referenzsignal für den Syn- chrondemodulator 13. Dessen Ausgangssignal kompensiert nach Filterung 14 über eine digitale Kompensation 15 über 19 und den AGC -Verstärker 18 am Phasenmodulator 10 die SAGNAC-Phase, so daß das Kompensationssignal der Drehrate bzw. im vorliegenden Fall dem Strom entspricht, das an einem Ausgang 20 unmittelbar als Digitalsignal zur Verfügung steht.in particular from a polarization-maintaining monomode fiber (PM fiber) with a certain length of, for example, 100 m, which is wound into a sensor coil 6. A phase modulator 10 is provided at one end of the closed light path, via which the operating point is set on the one hand and the rotation rate is reset or, in the present case, the current value is reset (will be explained in more detail below). The two opposing light beams are reunited after passing through the light path 5 in the main beam splitter and interfere with one another. The returning light beam passes via the polarizer 3 and the first beam splitter 2 to a photodetector 11 with a downstream filter and preamplifier, which feeds a demodulator 12 on the one hand and a synchronous demodulator 13 on the other hand, the reference frequency of which comes from a reference generator 16, which is a on the transit time of the light through the light path 5 tuned signal with randomly distributed Phasensprün- gene of n • λ / 4 supplies with which a signal adder 19, and an AGC amplifier 18 modulates the phase of light at the phase modulator 10 degrees. The phase jumps for odd n provide the reference signal for the synchronous demodulator 13. After filtering 14, its output signal compensates for the SAGNAC phase via digital compensation 15 via 19 and the AGC amplifier 18 on the phase modulator 10, so that the compensation signal of the rotation rate or in the present case corresponds to the current that is immediately available as a digital signal at an output 20.
Die Phasensprünge eines Referenzgenerators 16 für gerades n liefern das Referenzsignal für den Demodulator 12, dessen Ausgangssignal über ein Filter 17 die Verstärkung des AGC-Verstärkers 18 so steuert, daß das Ausgangssignal des Demodulators 12 Null ist. Damit wird der Skalenfaktor des Phasenmodulators 10 und damit auch der Skalenfaktor des Ausgangssignals geregelt.The phase jumps of a reference generator 16 for even n provide the reference signal for the demodulator 12, the output signal of which controls the gain of the AGC amplifier 18 via a filter 17 such that the output signal of the demodulator 12 is zero. This regulates the scale factor of the phase modulator 10 and thus also the scale factor of the output signal.
Erfindungsgemäß wird nach dem Grundkonzept der Erfindung die Sensorspule 6, jedoch insbesondere und vorzugsweise eine separate in den geschlossenen Lichtweg 5 eingesetzte oder einsetzbare Strommeßspule 7 als Stromsensor verwendet, die - wie dargestellt - vom Leiter 8 des zu messen- den Stroms bzw. von einem Leiter durchsetzt ist, der einen zum zu messenden Strom proportionalen Stromanteil führt. Das Meßprinzip basiert auf dem Faraday-Effekt. Die vom Strom durch den Leiter 8 verursachte Drehung - 4 -According to the basic concept of the invention, the sensor coil 6, but in particular and preferably a separate current measuring coil 7 inserted or usable in the closed light path 5, is used as the current sensor, which - as shown - from the conductor 8 of the current to be measured or from a conductor is enforced, which leads to a proportion of current proportional to the current to be measured. The measuring principle is based on the Faraday effect. The rotation caused by the current through conductor 8 - 4 -
der Polarisation des Lichts im Lichtweg 5 wird gemessen.the polarization of light in light path 5 is measured.
Die als spezielle Faserspule ausgeführte Strommeßspule 7 ist vorzugsweise aus einer Single-Mode-Faser mit einer Länge L hergestellt, wobei dafür zu sorgen ist, daß in der Strommeßspule 7 zumindest vorzugsweise zirkularpolarisiertes Licht fließt, um eine maximale Wirkung des Faraday-Effekts zu gewährleisten. Die Sensorspule 6 andererseits wird um die Länge L gekürzt (z.B. lOOm-L); sie ist aus PM-Faser gewickelt. Zur Optimierung des Faraday- Effekts und des Meßergebnisses sind vor der Strommeßspule 7 λ/4-Phasen- schieberelemente 9 χ , 92 eingesetzt, insbesondere verwirklicht mittels eines jeweils kurzen Stücks einer schwach doppelbrechenden PM-Faser. Die Spule 7 des Stromsensors wird vorzugsweise aus wärmebehandelter SM-Faser hergestellt; ihre Länge dient zur Anpassung an den jeweiligen Bereich der Stromstärke. Für eine Länge L = 5 m und einen Durchmesser der Strommeß- spule 7 von 5 cm ergeben sich ca. N = 15 Wicklungen. Damit lassen sich folgende Wertebereiche für die Strommessung erzielen:The current measuring coil 7, designed as a special fiber coil, is preferably made of a single-mode fiber with a length L, care being taken to ensure that circularly polarized light flows at least preferably in the current measuring coil 7, in order to ensure a maximum effect of the Faraday effect. The sensor coil 6, on the other hand, is shortened by the length L (e.g. 100m-L); it is wound from PM fiber. To optimize the Faraday effect and the measurement result 7 λ / 4-phase shifter elements 9 χ, 92 are used in front of the current measuring coil, in particular implemented by means of a short piece of weakly birefringent PM fiber. The coil 7 of the current sensor is preferably made of heat-treated SM fiber; their length serves to adapt to the respective range of the current strength. For a length L = 5 m and a diameter of the current measuring coil 7 of 5 cm, there are approximately N = 15 windings. The following value ranges can be achieved for the current measurement:
Empfindlichkeit 3.9 x 10~5 rad/ASensitivity 3.9 x 10 ~ 5 rad / A
Meßbereich (± π/2) + 40 kA Rauschanteil über den gesamtenMeasuring range (± π / 2) + 40 kA noise component over the entire
Meßbereich bei 1 kHz (0,6°/h 14 A.Measuring range at 1 kHz (0.6 ° / h 14 A.
Die Auflösung ist durch Rauschen auf 0,036% des Bereichs beschränkt. Der Strommeßbereich läßt sich durch die Länge L der Strommeßspule 7 anpas- sen.The resolution is limited to 0.036% of the range due to noise. The current measuring range can be adjusted by the length L of the current measuring coil 7.
Bei Verwendung eines bekannten Faserkreisels mit digitaler Rückstellung wird der "Umbau" zum Strommesser gemäß der Erfindung so verwirktlicht, daß zwei Faserenden des Lichtwegs 5 zur Minimierung des Vibrations-Shu- pe-Effekts vorzugsweise von der Mitte der Sensorspule 6 herausgeführt werden, wobei die λ/4-Phasenschieberelemente 9 ι , 92 und die Strommeßspule 7 innerhalb oder außerhalb des Gehäuse des Faserkreisels vorgesehen werden können. When using a known fiber optic gyro with digital reset, the "conversion" to the ammeter according to the invention is effected in such a way that two fiber ends of the light path 5 are preferably led out from the center of the sensor coil 6 to minimize the vibration-shock effect, the λ / 4-phase shifter elements 9, 92 and the current measuring coil 7 can be provided inside or outside the housing of the fiber gyroscope.

Claims

- 5 -Patentansprüche - 5 patent claims
1. Einrichtung zur Strommessung mittels eines faseroptischen Sagnac- Interferometers, in dessen Lichtweg (5), der von zwei durch Strahlteilung ei- 5 nes von einer Lichtquelle (1) stammenden Lichtstrahls entstandenen gegenläufigen Teillichtstrahlen durchsetzt wird, eine faseroptische Strommeßspule (7) eingesetzt ist, die von einem den zu messenden Strom oder einem dazu proportionalen Stromanteil führenden Leiter (8) durchsetzt ist, dadurch gekennzeichnet, daß der Aufbau des faseroptischen Sagnac-Interferometers 10 einem Faserkreisel mit geschlossener Regelschleife entspricht, bei dem die Strommeßspule (7) die Sensorspule (6) mindestens teilweise ersetzt.1. Device for current measurement by means of a fiber-optic Sagnac interferometer, in whose light path (5), which is penetrated by two opposing partial light beams created by beam splitting one from a light source (1), a fiber-optic current measuring coil (7) is used which is traversed by a conductor (8) carrying the current to be measured or a proportion of current proportional thereto, characterized in that the structure of the fiber-optic Sagnac interferometer 10 corresponds to a fiber gyroscope with a closed control loop, in which the current measuring coil (7) and the sensor coil ( 6) at least partially replaced.
..
2. Einrichtung nach Anspruch 1 , dadurch gekennzeichnet, daß in den von den gegenläufigen Teillichtstrahlen durchsetzten Lichtweg (5) jeweils vor 15 den Anschließenden der Strommeßspule (7) ein λ/4-Phasenschieber (9 i t 92) eingesetzt ist.2. Device according to claim 1, characterized in that a λ / 4-phase shifter (9 it 92) is inserted in the light path (5) penetrated by the opposing partial light beams (5) in each case before 15 the connecting ends of the current measuring coil (7).
3. Einrichtung nach Anspruch 2, dadurch gekennzeichnet, daß die λ/4- Phasenschieber (9χ, 92) jeweils durch ein kurzes Stück einer schwach dop- -20 pelbrechenden Faser verwirklicht sind.3. Device according to claim 2, characterized in that the λ / 4-phase shifters (9χ, 92) are each realized by a short piece of a weakly double-20 ple refractive fiber.
-4. Einrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Strommeßspule (7) aus wärmebehandelter Single- Mode-Faser hergestellt ist. 25-4. Device according to one of the preceding claims, characterized in that the current measuring coil (7) is made of heat-treated single-mode fiber. 25
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PCT/EP1999/000549 1998-02-27 1999-01-28 Device for measuring a current by means of a fibre-optic sagnac interferometer WO1999044070A1 (en)

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EP99904822A EP1058853A1 (en) 1998-02-27 1999-01-28 Device for measuring a current by means of a fibre-optic sagnac interferometer

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1998108517 DE19808517A1 (en) 1998-02-27 1998-02-27 Current measurement device
DE19808517.6 1998-02-27

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WO1999044070A1 true WO1999044070A1 (en) 1999-09-02

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Publication number Priority date Publication date Assignee Title
DE10000306B4 (en) * 2000-01-05 2012-05-24 Abb Research Ltd. Fiber optic current sensor
DE10044197B4 (en) * 2000-09-07 2004-08-19 Litef Gmbh Method and device for electro-optical measurement of electrical voltage
DE10112835B4 (en) 2001-03-16 2006-05-11 Litef Gmbh Method and device for current measurement by means of a fiber optic in-line Sagnac interferometer and suitable phase modulator
DE10138154C2 (en) 2001-08-03 2003-06-05 Litef Gmbh Method and device for increasing the long-term operational reliability of a fiber optic interferometer

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