WO2005098458A1 - Current sensor - Google Patents

Current sensor Download PDF

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Publication number
WO2005098458A1
WO2005098458A1 PCT/EP2005/003584 EP2005003584W WO2005098458A1 WO 2005098458 A1 WO2005098458 A1 WO 2005098458A1 EP 2005003584 W EP2005003584 W EP 2005003584W WO 2005098458 A1 WO2005098458 A1 WO 2005098458A1
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WIPO (PCT)
Prior art keywords
winding
current sensor
coupling element
current
sensor according
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PCT/EP2005/003584
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German (de)
French (fr)
Inventor
Michael Naumann
Markus Miklis
Original Assignee
Ellenberger & Poensgen Gmbh
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Publication of WO2005098458A1 publication Critical patent/WO2005098458A1/en

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    • 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
    • G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils

Definitions

  • the invention relates to a current sensor for detecting current changes as a result of arcs in the frequency range between 400 kHz and 60 MHz.
  • a current sensor based on the principle of the Rogowski coil is often used to measure a current flowing through a primary conductor.
  • This sensor which consists of an air coil without a ferromagnetic core, provides an output signal in the form of a voltage that is proportional to the current flowing through the primary conductor.
  • Such a Rogowski coil is therefore also used in particular to detect a time-varying electrical current.
  • the variable magnetic field between the ends of the coil conductor led around the primary conductor induces the voltage which is dependent on the change in the current over time.
  • the Rogowski coil is usually realized by an electrically conductive coil in the form of wire-shaped conductors wound on a toroidal body made of non-ferromagnetic material or by conductor tracks that radially on a non-conductive plate provided with a central hole are arranged running to the center of the hole.
  • the primary conductor carrying the current to be detected is guided centrally through the opening formed by the toroidal body or through the plate hole.
  • Rogowski coil requires a relatively large-area sensor design.
  • the measurable signal level is very small, which requires complex and therefore expensive electronics for signal evaluation.
  • interference fields are also detected with a Rogowski coil.
  • the invention is based on the object of specifying a current sensor which is particularly suitable for detecting events as a result of arcs.
  • the current sensor should reliably detect rapid changes in current or, in particular, steep-edged current increases (dl / dt) with the least possible effort.
  • This object is achieved according to the invention by the features of claim 1.
  • the current sensor comprises a ferromagnetic coupling element and a sensor winding surrounding it with a number of sensor windings, and an excitation winding carrying the current to be detected.
  • a current or voltage signal can be tapped at the connection ends of the sensor winding, which results from the change in slope (d 2 lp / dt 2 ) as a result of high-frequency signal components in the current signal and the damping or amplification as a result of the coupling of the sensor winding to the excitation winding via the ferromagnetic coupling element.
  • This signal is expediently sampled in an analog / digital converter, for example by means of a comparator or 1-bit converter.
  • the detectable frequency range is between approximately 400 kHz and approximately 60 MHz.
  • the essential assembly of the sensor consisting of the sensor winding and the coupling element made of ferromagnetic material, is coupled to the excitation winding by forming a distance via the coupling element.
  • both the sensor and the excitation winding expediently surround the coupling element, forming an insulation distance.
  • the field winding and the sensor winding are arranged next to one another to form a distance on the coupling element.
  • the field winding preferably coaxially surrounds the sensor winding, the coupling element then lying axially in the center of the sensor.
  • This variant has the advantage that a practically arbitrary conductor thickness, ie. H. a winding conductor with a comparatively large conductor diameter can be used.
  • the primary conductor carrying the current to be measured is therefore not passed through a sensor coil, but rather runs on or on the common coupling element adjacent to or above the sensor winding.
  • the excitation winding which carries the current whose rapid current changes are to be recorded, comprises a quarter turn to ten turns.
  • the excitation winding can represent an elongated conductor or comprise half a turn, that is to say a loop open on one side, an entire turn or even several turns.
  • the field winding expediently comprises at least one half be turn, preferably one and a half turns.
  • the number of turns of the secondary winding can be half a turn to fifteen turns or more than fifteen turns.
  • the detectable frequency range from approx. 400 kHz to approx. 60 MHz and the size of the signal that can be picked up at the sensor development are influenced by the mass, the material and the geometry of the coupling element as well as by the number of turns of the excitation or sensor winding and their geometric arrangement ,
  • the coupling element expediently consists of a preferably cylindrical ferrite core, which can also be hollow.
  • a diameter of 1 mm to 10 mm, preferably 2 mm, and a length of 2 mm to 40 mm, preferably 15 mm, are particularly suitable.
  • the number of excitation turns is preferably one and a half, while the number of sensor turns is preferably greater than or equal to four and a half.
  • the mass of the coupling element is between 0.1g and 2g, preferably 0.2g.
  • An evaluation electronics connected to the connection ends of the sensor winding, preferably in the form of an analog / digital converter with downstream signal processing, detects and processes directly the frequency-dependent sensor signal that can be tapped at the connections of the sensor winding, ie. H. a sensor signal with frequency-dependent amplitude. This signal generated by the sensor is larger or higher the higher the slope of the current change. Such a rapid current change (dl / dt) is stored in or by means of the coupling element and is thus damped or amplified.
  • the sensor signal that can be tapped at the connection ends of the sensor winding is standardized by means of the analog / digital converter to an adjustable value, the pulse height or logic voltage and pulse duration of which can be predetermined by a reference signal.
  • the pulse Duration or temporal pulse length of the output signal of the analog / digital converter is determined in particular by the mass of the coupling element and thus by the damping or amplification caused by the current sensor.
  • the samples of the signal digitized by means of the analog / digital converter are expediently counted or summed up.
  • the determined sum then contains a certain count value, which in turn can be assigned to a causal event.
  • the sum is greater, the more events have occurred per time unit of the scan. As a result of the summation, the data rate is reduced.
  • the discrete-time summation also enables simple signal evaluation.
  • the current sensor which is designed with the ferromagnetic coupling element in particular, provides a comparatively high signal level, in contrast to the Rogowski principle, with at the same time very small structural dimensions and therefore a small overall structure.
  • the signal levels are sufficiently high or high that simple processing is possible without further signal amplification.
  • the current sensor does not carry out a proportional current measurement, but reliably detects changes in the current strength in the frequency range to be detected from 400 kHz to ⁇ OMHhz.
  • the sensor winding of the current sensor is galvanically isolated from the current-carrying excitation conductor in a simple and reliable manner during the measurement, without the current sensor having to meet exact symmetry requirements.
  • the design of the sensor winding with respect to the current-carrying conductor is much freer.
  • the current sensor can thus be integrated into a housing with correspondingly small housing dimensions and / or advantageously also into a circuit breaker.
  • the current sensor itself does not require any further components, since due to the high signal level there are no agile signal processing is required.
  • signals in the frequency range from 400 kHz to 60 MHz can be reliably detected with regard to steep-edged current changes without additional filter measures. Practically every arc can be detected, which can always occur when two different voltage potentials on surfaces, conductors or the like. be performed and their electrical insulation to each other is insufficient.
  • Steep-edged current changes such as those generated by electrical consumers in the respective primary conductor, can also be reliably detected.
  • FIG. 1 schematically, in perspective, a current sensor according to the invention connected to a comparator with signal processing
  • FIG. 2a and 2b an end view of a sensor winding or an excitation winding of the current sensor
  • Fig. 3 in a diagram, the damping or amplification of the current sensor depending on the frequency
  • Fig. 4 schematically in a diagram, a current signal with steep-edged current change and a sensor output signal generated by the current sensor and a standardized output signal of the comparator
  • Fig. 5 in the upper part of the diagram a consumer current with interference components and in the lower part of the diagram an event rate as the output signal of the signal processing
  • Fig. 6 in a representation according to Fig. 5 the event rate as the output signal of the signal processing as a result of a switching operation
  • FIG. 7 is a front view of the current sensor according to the invention with the field winding coaxially surrounding the sensor winding.
  • the current sensor 1 comprises a sensor winding or coil 2 which, like an excitation winding 3, is wound around a common coupling element 4.
  • the cylindrical or rod-shaped and ferromagnetic coupling element 4 penetrates both windings 2, 3 in one piece.
  • the sensor winding 2 consisting of a plurality of sensor windings 5 and the excitation winding 3, which may also consist of a plurality of windings 6, are arranged on the coupling element 4, forming a distance a.
  • the coupling element 4 and the two windings 2, 3 are arranged in a sensor housing 7, the connection ends of the excitation winding 3 being guided inside the housing to corresponding connections 8a, 8b.
  • the housing 7 can also be that of an electronic circuit breaker or circuit breaker relay.
  • the distance b between the excitation winding 3 and the corresponding core end 4a of the coupling element 4 is preferably in the range of a few millimeters, eg. B. 2mm to 5mm.
  • the distance b should be equal to the width c of the excitation winding 3 on the coupling element 4.
  • the corresponding distance d between the sensor winding 2 and the opposite core end 4b can be dimensioned in the same order of magnitude.
  • the outer diameter D of the coupling element 4 is between 1 mm and 10 mm, preferably 2 mm.
  • the length L of the coupling element 4 is between 2mm and 40mm, preferably 15mm.
  • the mass of the coupling element is between 0.1g and 2g, preferably 0.2g.
  • the secondary windings 5 of the sensor winding 2 are guided around the coupling element 4 to form an insulation distance f. This in turn depends on the electrical requirements.
  • the insulation distance f is formed by a suitable insulation medium or material, preferably air.
  • the excitation winding 3 is guided around the coupling element 4 with an insulation distance g.
  • the insulation medium is also preferably air.
  • the distances a, f and g are essentially dependent on the electrical and / or thermal insulation requirements specified by the intended use.
  • the number of secondary turns 5 for forming the sensor winding 2 is 1 A.
  • the sensor winding 2 can also have more or fewer turns, for example two to ten turns.
  • the number of excitation windings is V ⁇ in the exemplary embodiment.
  • the excitation winding 3 can be a conductor running at a distance g across the coupling element 4 and carrying the current Ip to be detected.
  • the field winding 3 is the line carrying the current Ip itself or a line section which can be connected to it.
  • a voltage is induced in the sensor winding 2 as a result of a temporal change dlp / dt of the current Ip and on the basis of a concentration of the magnetic field generated by the rapid current change achieved by means of the coupling element 4.
  • a voltage signal S with a relatively high signal level can be tapped at the connection ends 2a, 2b of the sensor winding 2.
  • the gradient change d 2 lp / dt 2 of the rapid current change detected by the current sensor 1 results in a signal S which is greater or stronger the more steeply the current change dlp / dt is.
  • such a rapid current change dlp / dt is stored in or by means of the coupling element 4 and thus extended in time, as is illustrated in FIG. 4.
  • FIG. 4 shows schematically in the upper diagram the course of the detected excitation current Ip over time t with a steep-sided current change dlp / dt from a comparatively lower current value Ipi to a comparatively high current value lp 2 .
  • the middle representation in FIG. 4 shows the signal S at the inputs Ei of an analog / digital converter (A / D converter) 9 in response to the rapid current change or the change in the gradient d 2 lp / dt 2 .
  • Fig. 3 shows the dependence of the attenuation ⁇ of the signal S at the inputs Ei as a function of the frequency f for a sensor winding 2 with 4% turns and an excitation winding 3 with V ⁇ turns and a length L of the coupling element 4 of 15mm with an outer diameter D. of 2mm and a mass of the coupling element 4 of 0.2g.
  • the signal S which can be tapped at the sensor winding 2 is fed to the input Ei of the A / D converter 9, which is expediently designed as a comparator, of an evaluation device or electronics.
  • the further input E 2 of the comparator and thus of the A / D converter 9 designed as a 1 bit converter is a reference signal U R ⁇ f in the form of a voltage of z. B.
  • the A / D conversion converts the input or sensor signal S to the reference or logic voltage U Ref with a pulse width ⁇ t of z.
  • the pulse duration or temporal pulse length ⁇ t of the output signal P of the A / D converter 9 is in particular also determined by the mass of the coupling element 4 and thus by the damping ⁇ or amplification V of the signal S.
  • the sensor signal S normalized as a result of the A / D conversion at the output A of the converter 9 is illustrated in the lower illustration in FIG. 4. It can be seen that the A / D converter or comparator 9 responds to a rapid current increase dlp / dt with a short-time pulse P of the pulse length ⁇ t.
  • the output signals or digital values P of the A / D converter 9 are summed up in a processing device 10 connected downstream of this, hereinafter referred to as signal processing. Its input It is connected to the output A of the A / D converter 9.
  • a corresponding number or event rate R can be tapped off at a time interval at output B of signal processing 10.
  • the respective event rates R can - as shown in FIGS. 5 and 6 - be represented graphically.
  • the A / D converter 9 and the signal processing 10 are also arranged in the sensor housing 7.
  • the output B of the signal processing 10 is routed to a corresponding, analog or digital connection 11, via which the event rates R can be read out.
  • Further connections 12, 13 are provided for the supply voltage U B or ground.
  • FIG. 5 shows several half-waves of an excitation current I with SHF interference as a result of high-frequency signal components. These high-frequency signal components, which are not qualitatively or only extremely difficult to detect with conventional current measurements or can only be detected with high measurement complexity, are detected as such by the current sensor 1.
  • the short-term pulses P are summed in the signal processing 10 for a simplified graphical representation to the event rate R in a time interval.
  • FIG. 6 shows a typical current signal Ip recorded by conventional means as a result of a consumer being switched off.
  • the course of the current signal Ip shows a decrease in the current Ip over time t as a result of the switching off of one of several consumers.
  • the signal shown in the lower part of the diagram shows the event rate R determined by the signal processing 10. The arc generated in the switch for a short time was detected by the current sensor 1.
  • FIG. 7 shows an alternative embodiment of the current sensor 1, in which the excitation winding 3 is not located next to but above the sensor winding 2. This in turn surrounds the coupling element 4.
  • Such a geometric configuration of the current sensor 1 has the advantage that the conductor cross section of the excitation winding 3 can be comparatively large.
  • the current sensor 1 also reliably detects such high-frequency current changes in a current Ip to be detected that would previously have been detectable only with considerable expenditure on measurement technology. Since such steep-edged current changes occur in particular in the event of arcing faults, which lead, for example, as a result of equipotential bonding between two different voltage potentials and e.g. B. neighboring conductors having insulation defects, the current sensor 1 is particularly suitable, particularly because of its small dimensions and simple evaluation, also for detecting arcs in aircraft on-board networks (arc tracking). LIST OF REFERENCE NUMBERS

Abstract

The inventive current sensor (1) for detecting particularly steep-edged current changes (dl/dt) comprises a ferromagnetic coupling element (4) and a sensor winding (2) which surrounds it with a plurality of secondary windings (5), in addition to an excitation winding (3) which guides the current (Ip).

Description

Beschreibung description
Stromsensorcurrent sensor
Die Erfindung bezieht sich auf einen Stromsensor zur Erfassung von Stromänderungen in Folge von Lichtbögen im Frequenzbereich zwischen 400kHz und 60MHz.The invention relates to a current sensor for detecting current changes as a result of arcs in the frequency range between 400 kHz and 60 MHz.
Zur Messung eines durch einen Primärleiter fließenden Stromes wird häufig ein auf dem Prinzip der Rogowski-Spule basierender Stromsensor eingesetzt. Dieser aus einer Luftspule ohne ferromagnetischen Kern bestehende Sensor liefert ein Ausgangssignal in Form einer Spannung, die proportional zum den Primärleiter durchfließenden Strom ist. Eine derartige Rogowski-Spule wird daher insbesondere auch zur Erfassung eines sich zeitlich ändernden elektrischen Stroms eingesetzt. Dabei induziert das variable magnetische Feld zwischen den Enden des um den Primärleiter herumgeführten Spu- lenleiters die von der zeitlichen Änderung des Stromes abhängige Spannung.A current sensor based on the principle of the Rogowski coil is often used to measure a current flowing through a primary conductor. This sensor, which consists of an air coil without a ferromagnetic core, provides an output signal in the form of a voltage that is proportional to the current flowing through the primary conductor. Such a Rogowski coil is therefore also used in particular to detect a time-varying electrical current. The variable magnetic field between the ends of the coil conductor led around the primary conductor induces the voltage which is dependent on the change in the current over time.
Die Rogowski-Spule ist dabei üblicherweise realisiert durch eine auf einen torus- förmigen Körper aus nicht-ferromagnetischem Material gewickelte elektrisch leitende Spule in Form von drahtförmigen Leitern oder durch Leiterbahnen, die auf einer mit ei- nem zentralen Loch versehenen, nicht-leitenden Platte radial zum Lochmittelpunkt verlaufend angeordnet sind. Dabei ist der den zu erfassenden Strom führende Primärleiter durch die vom torusförmigen Körper gebildete Öffnung bzw. durch das Plattenloch zentral hindurchgeführt.The Rogowski coil is usually realized by an electrically conductive coil in the form of wire-shaped conductors wound on a toroidal body made of non-ferromagnetic material or by conductor tracks that radially on a non-conductive plate provided with a central hole are arranged running to the center of the hole. The primary conductor carrying the current to be detected is guided centrally through the opening formed by the toroidal body or through the plate hole.
Der Einsatz einer Rogowski-Spule bedingt jedoch eine relativ großflächige Sensorkonstruktion. Zudem ist der messbare Signalpegel sehr klein, was zur Signalauswertung eine aufwändige und daher kostenintensive Elektronik erfordert. Ferner werden mit einer Rogowski-Spule auch Störfelder erfasst.However, the use of a Rogowski coil requires a relatively large-area sensor design. In addition, the measurable signal level is very small, which requires complex and therefore expensive electronics for signal evaluation. Furthermore, interference fields are also detected with a Rogowski coil.
Der Erfindung liegt die Aufgabe zu Grunde, einen zur Detektion von Ereignissen in Folge von Lichtbögen besonders geeigneten Stromsensor anzugeben. Der Stromsensor soll dabei schnelle Stromänderungen oder insbesondere auch steilflankige Stromanstiege (dl/dt) mit geringstmöglichem Aufwand zuverlässig erfassen. Diese Aufgabe wird erfindungsgemäß gelöst durch die Merkmale des Anspruchs 1. Dazu umfasst der Stromsensor ein ferromagnetisches Koppelelement und eine dieses mit einer Anzahl von Sensorwindungen umgebende Sensorwicklung sowie eine den zu erfassenden Strom führende Erregerwicklung. An den Anschlussenden der Sensorwicklung ist ein Strom- oder Spannungssignal abgreifbar, das aus der Steigungsänderung (d2lp/dt2) infolge hochfrequenter Signalanteile im Stromsignal und der Dämpfung bzw. Verstärkung infolge der Kopplung der Sensorwicklung mit der Erregerwicklung über das ferromagnetische Koppelelement resultiert. Dieses Signal wird zweck- mäßigerweise in einem Analog/Digital-Wandler, beispielsweise mittels eines Kompara- tors oder 1 bit-Wandlers, abgetastet. Der detektierbare Frequenzbereich liegt dabei zwischen ca. 400 kHz und etwa 60 MHz.The invention is based on the object of specifying a current sensor which is particularly suitable for detecting events as a result of arcs. The current sensor should reliably detect rapid changes in current or, in particular, steep-edged current increases (dl / dt) with the least possible effort. This object is achieved according to the invention by the features of claim 1. For this purpose, the current sensor comprises a ferromagnetic coupling element and a sensor winding surrounding it with a number of sensor windings, and an excitation winding carrying the current to be detected. A current or voltage signal can be tapped at the connection ends of the sensor winding, which results from the change in slope (d 2 lp / dt 2 ) as a result of high-frequency signal components in the current signal and the damping or amplification as a result of the coupling of the sensor winding to the excitation winding via the ferromagnetic coupling element. This signal is expediently sampled in an analog / digital converter, for example by means of a comparator or 1-bit converter. The detectable frequency range is between approximately 400 kHz and approximately 60 MHz.
Die aus der Sensorwicklung und dem Koppelelement aus ferromagnetischem Material bestehende wesentliche Baugruppe des Sensors wird unter Bildung eines Abstandes über das Koppelelement mit der Erregerwicklung gekoppelt. Dazu umgeben zweckmäßigerweise sowohl die Sensor- als auch die Erregerwicklung das Koppelelement unter Bildung eines Isolationsabstandes. Die Erregerwicklung und die Sensorwicklung sind dabei unter Bildung eines Abstandes auf dem Koppelelement nebeneinander an- geordnet. Alternativ umgibt die Erregerwicklung die Sensorwicklung vorzugsweise koaxial, wobei dann das Koppelelement axial im Zentrum des Sensors liegt. Diese Variante hat den Vorteil, dass für die Erregerwicklung eine praktisch beliebige Leiterdicke, d. h. ein Wicklungsleiter mit vergleichsweise großem Leiterdurchmesser verwendet werden kann. Die Erregerwicklung, d. h. der den zu messenden Strom führende Pri- märleiter ist somit nicht durch eine Sensorspule hindurchgeführt, sondern verläuft auf oder an dem gemeinsamen Koppelelement benachbart zur bzw. über der Sensorwicklung.The essential assembly of the sensor, consisting of the sensor winding and the coupling element made of ferromagnetic material, is coupled to the excitation winding by forming a distance via the coupling element. For this purpose, both the sensor and the excitation winding expediently surround the coupling element, forming an insulation distance. The field winding and the sensor winding are arranged next to one another to form a distance on the coupling element. Alternatively, the field winding preferably coaxially surrounds the sensor winding, the coupling element then lying axially in the center of the sensor. This variant has the advantage that a practically arbitrary conductor thickness, ie. H. a winding conductor with a comparatively large conductor diameter can be used. The excitation winding, d. H. The primary conductor carrying the current to be measured is therefore not passed through a sensor coil, but rather runs on or on the common coupling element adjacent to or above the sensor winding.
Die Erregerwicklung, die denjenigen Strom führt, dessen schnelle Stromänderungen erfasst werden sollen, umfasst eine viertel Windung bis zehn Windungen. Dabei kann die Erregerwicklung einen langgestreckten Leiter darstellen oder eine halbe Windung, also eine einseitig offene Schlaufe, eine ganze Windung oder auch mehrere Windungen umfassen. Zweckmäßigerweise umfasst die Erregerwicklung mindestens eine hal- be Windung, vorzugsweise eineinhalb Windungen. Bezüglich der Anzahl der Windungen sowohl der Erregerwicklung als auch der Sensorwicklung ist dabei berücksichtigt, dass erkanntermaßen hinsichtlich elektrischer Kriterien möglichst wenige Wind ungen und hinsichtlich signaltechnischer Kriterien möglichst viele Windungen verwendet wer- den.The excitation winding, which carries the current whose rapid current changes are to be recorded, comprises a quarter turn to ten turns. The excitation winding can represent an elongated conductor or comprise half a turn, that is to say a loop open on one side, an entire turn or even several turns. The field winding expediently comprises at least one half be turn, preferably one and a half turns. With regard to the number of turns of both the excitation winding and the sensor winding, it is taken into account that it is recognized that as few turns as possible with regard to electrical criteria and as many turns as possible with regard to signaling criteria are used.
Die Windungszahl der Sekundärwicklung kann eine halbe Windung bis fünfzehn Windungen oder auch größer fünfzehn Windungen sein. Der detektierbare Frequenzbereich von etwa 400kHz bis ca. 60MHz und die Größe des an der Sensorwicl lung abgreifbaren Signals werden beeinflusst durch die Masse, das Material und die Geometrie des Koppelelementes sowie durch die Anzahl der Windungen der Erreg er- bzw. Sensorwicklung und deren geometrische Anordnung.The number of turns of the secondary winding can be half a turn to fifteen turns or more than fifteen turns. The detectable frequency range from approx. 400 kHz to approx. 60 MHz and the size of the signal that can be picked up at the sensor development are influenced by the mass, the material and the geometry of the coupling element as well as by the number of turns of the excitation or sensor winding and their geometric arrangement ,
Das Koppelelement besteht zweckmäßigerweise aus einem vorzugsweise zylindrischen Ferritkern, der auch hohl ausgeführt sein kann. Hinsichtlich der Abmessungen des Koppelelements sind ein Durchmesser von 1mm bis 10mm, vorzugsweise 2mm, und eine Länge von 2mm bis 40mm, vorzugsweise 15mm, besonders geeignet. Die Anzahl der Erregerwindungen beträgt vorzugsweise eineinhalb, während die Anzahl der Sensorwindungen vorzugsweise größer oder gleich viereinhalb ist. Die Masse des Koppel- elementes beträgt zwischen 0,1g und 2g, vorzugsweise 0,2g.The coupling element expediently consists of a preferably cylindrical ferrite core, which can also be hollow. With regard to the dimensions of the coupling element, a diameter of 1 mm to 10 mm, preferably 2 mm, and a length of 2 mm to 40 mm, preferably 15 mm, are particularly suitable. The number of excitation turns is preferably one and a half, while the number of sensor turns is preferably greater than or equal to four and a half. The mass of the coupling element is between 0.1g and 2g, preferably 0.2g.
Eine mit den Anschlussenden der Sensorwicklung verbundene Auswerteelektronik, vorzugsweise in Form eines Analog/Digital-Wandlers mit nachgeschalteter Signalverarbeitung, erfasst und verarbeitet direkt das an den Anschlüssen der Sensorwicklung abgreifbare frequenzabhängige Sensorsignal, d. h. ein Sensorsignal mit freque nzabhängiger Amplitude. Dieses von dem Sensor erzeugte Signal ist dabei um so g rößer oder höher, je steilflankiger die Stromänderung ist. Eine solche schnelle Stromände- rung (dl/dt) wird im oder mittels des Koppelelementes gespeichert und damit gedämpft bzw. verstärkt.An evaluation electronics connected to the connection ends of the sensor winding, preferably in the form of an analog / digital converter with downstream signal processing, detects and processes directly the frequency-dependent sensor signal that can be tapped at the connections of the sensor winding, ie. H. a sensor signal with frequency-dependent amplitude. This signal generated by the sensor is larger or higher the higher the slope of the current change. Such a rapid current change (dl / dt) is stored in or by means of the coupling element and is thus damped or amplified.
Das an den Anschlußenden der Sensorwicklung abgreifbare Sensorsignal wird mittels des Analog/Digital-Wandlers auf einen einstellbaren Wert normiert, dessen Pul shöhe oder Logikspannung und Pulsdauer durch ein Referenzsignal vorgebbar ist. Die Puls- dauer oder zeitliche Pulslänge des Ausgangssignals des Analog/Digital-Wandlers wird insbesondere auch durch die Masse des Koppelelementes und damit durch die mit dem Stromsensor bewirkte Dämpfung bzw. Verstärkung bestimmt.The sensor signal that can be tapped at the connection ends of the sensor winding is standardized by means of the analog / digital converter to an adjustable value, the pulse height or logic voltage and pulse duration of which can be predetermined by a reference signal. The pulse Duration or temporal pulse length of the output signal of the analog / digital converter is determined in particular by the mass of the coupling element and thus by the damping or amplification caused by the current sensor.
Die Abtastwerte des mittels des Analog/Digital-Wandlers digitalisierten Signals wird zweckmäßigerweise gezählt oder aufsummiert. Die ermittelte Summe enthält dann einen bestimmten Zählwert, der wiederum einem ursächlichen Ereignis zugeordnet werden kann. Die Summe ist dabei umso größer, je mehr Ereignisse pro Zeiteinheit der Abtastung aufgetreten sind. In Folge der Summation wird eine Reduktion der Datenrate erreicht. Durch die zeitdiskrete Summation ist zudem eine einfache Signalauswertung ermöglicht.The samples of the signal digitized by means of the analog / digital converter are expediently counted or summed up. The determined sum then contains a certain count value, which in turn can be assigned to a causal event. The sum is greater, the more events have occurred per time unit of the scan. As a result of the summation, the data rate is reduced. The discrete-time summation also enables simple signal evaluation.
Die mit der Erfindung erzielten Vorteile bestehen insbesondere darin, dass der mit dem insbesondere ferromagnetischen Koppelelement ausgeführte Stromsensor im Gegen- satz zum Rogowski-Prinzip bei gleichzeitig sehr geringen konstruktiven Abmessungen und daher kleinem Gesamtaufbau einen vergleichsweise hohen Signalpegel liefert. Die Signalpegel sind ausreichend groß bzw. hoch, so dass eine einfache Verarbeitung ohne weitere Signalverstärkung möglich ist. Der Stromsensor führt dabei keine proportionale Strommessung durch, sondern erfasst zuverlässig Änderungen der Stromstärke im zu detektierenden Frequenzbereich von 400kHz bis ΘOMHhz.The advantages achieved by the invention are, in particular, that the current sensor, which is designed with the ferromagnetic coupling element in particular, provides a comparatively high signal level, in contrast to the Rogowski principle, with at the same time very small structural dimensions and therefore a small overall structure. The signal levels are sufficiently high or high that simple processing is possible without further signal amplification. The current sensor does not carry out a proportional current measurement, but reliably detects changes in the current strength in the frequency range to be detected from 400 kHz to ΘOMHhz.
Zudem ist die Sensorwicklung des Stromsensors auf einfache sowie zuverlässige Art und Weise vom Strom führenden Erregerleiter während der Messung galvanisch getrennt, ohne dass der Stromsensor exakte Symmetrievoraussetzungen erfüllen muß. Daher ist eine im Vergleich zum Rogowski-Sensor wesentlich freiere konstruktive Positionierung der Sensorwicklung zum Strom führenden Leiter erreicht.In addition, the sensor winding of the current sensor is galvanically isolated from the current-carrying excitation conductor in a simple and reliable manner during the measurement, without the current sensor having to meet exact symmetry requirements. Compared to the Rogowski sensor, the design of the sensor winding with respect to the current-carrying conductor is much freer.
Insbesondere aufgrund der sehr geringen Abmessungen des Stromsensors eignet sich dieser besonders vorteilhaft zur Messung von Ereignissen in Systemen, bei denen be- sondere Anforderungen an Gewicht und Volumen gestellt werden. So kann der Stromsensor in ein Gehäuse mit entsprechend geringen Gehäuseabmessungen und/oder vorteilhaft auch in einen Schutzschalter integriert werden. Der Stromsensor selbst benötigt keinerlei weitere Bauelemente, da aufgrund des hohen Signalpegels keine auf- wendige Signalaufbereitung erforderlich ist. Zudem können Signale im Frequenzbereich von 400 kHz bis 60 MHz ohne zusätzliche Filtermaßnahmen zuverlässig hinsichtlich steilflankiger Stromänderungen detektiert werden. Dabei ist praktisch jeder Lichtbogen detektierbar, der immer dann entstehen kann, wenn zwei unterschiedliche Spannungs- potentiale an Flächen, Leitern o.dgl. geführt werden und deren elektrische Isolation zueinander nicht ausreichend ist. Auch sind steilflankige Stromänderungen, wie diese von elektrischen Verbrauchern im jeweiligen Primärleiter erzeugt werden können, zuverlässig detektierbar.In particular due to the very small dimensions of the current sensor, it is particularly advantageously suitable for measuring events in systems in which special requirements are placed on weight and volume. The current sensor can thus be integrated into a housing with correspondingly small housing dimensions and / or advantageously also into a circuit breaker. The current sensor itself does not require any further components, since due to the high signal level there are no agile signal processing is required. In addition, signals in the frequency range from 400 kHz to 60 MHz can be reliably detected with regard to steep-edged current changes without additional filter measures. Practically every arc can be detected, which can always occur when two different voltage potentials on surfaces, conductors or the like. be performed and their electrical insulation to each other is insufficient. Steep-edged current changes, such as those generated by electrical consumers in the respective primary conductor, can also be reliably detected.
Nachfolgend werden Ausführungsbeispiele der Erfindung anhand einer Zeichnung näher erläutert. Darin zeigen:Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. In it show:
Fig. 1 schematisch in perspektivischer Darstellung einen an einem Kom- parator mit Signalverarbeitung angeschlossenen erfindungsge- mäßen Stromsensor,1 schematically, in perspective, a current sensor according to the invention connected to a comparator with signal processing,
Fig. 2a und 2b eine Stirnansicht auf eine Sensorwicklung bzw. auf eine Erregerwicklung des Stromsensors, Fig. 3 in einem Diagramm die Dämpfung bzw. Verstärkung des Stromsensors in Abhängigkeit von der Frequenz, Fig. 4 schematisch in einer Diagrammdarstellung ein Stromsignal mit steilflankiger Stromänderung und ein mittels des Stromsensors generiertes Sensorausgangssignal sowie ein normiertes Ausgangssignal des Komparators, Fig. 5 im oberen Diagrammteil ein Verbraucherstrom mit Störanteilen und im unteren Diagrammteil eine Ereignisrate als Ausgangssignal der Signalverarbeitung, Fig. 6 in einer Darstellung gemäß Fig. 5 die Ereignisrate als Ausgangssignal der Signalverarbeitung in Folge eines Schaltvorgangs, und. Fig. 7 in einer Stirnansicht den erfindungsgemäßen Stromsensor mit die Sensorwicklung koaxial umgebender Erregerwicklung.2a and 2b an end view of a sensor winding or an excitation winding of the current sensor, Fig. 3 in a diagram, the damping or amplification of the current sensor depending on the frequency, Fig. 4 schematically in a diagram, a current signal with steep-edged current change and a sensor output signal generated by the current sensor and a standardized output signal of the comparator, Fig. 5 in the upper part of the diagram a consumer current with interference components and in the lower part of the diagram an event rate as the output signal of the signal processing, Fig. 6 in a representation according to Fig. 5 the event rate as the output signal of the signal processing as a result of a switching operation, and. 7 is a front view of the current sensor according to the invention with the field winding coaxially surrounding the sensor winding.
Einander entsprechende Teile sind in allen Figuren mit den gleichen Bezugszeichen versehen. Gemäß den Figuren 1 und 2 umfasst der Stromsensor 1 eine Sensorwicklung oder - spule 2, die ebenso wie eine Erregerwicklung 3 um ein gemeinsames Koppelelement 4 gewickelt ist. Das zylinder- oder stabförmig ausgebildete und ferromagnetische Koppel- element 4 durchdringt beide Wicklungen 2, 3 einstückig. Dabei sind die aus mehreren Sensorwindungen 5 bestehende Sensorwicklung 2 und die Erregerwicklung 3, die e- benfalls aus mehreren Windungen 6 bestehen kann, unter Bildung eines Abstandes a auf dem Koppelelement 4 angeordnet. Das Koppelelement 4 und die beiden Wicklungen 2, 3 sind in einem Sensorgehäuse 7 angeordnet, wobei die Anschlußenden der Erregerwicklung 3 gehäuseintern an entsprechende Anschlüsse 8a, 8b geführt sind. Das Gehäuse 7 kann auch dasjenige eines elektronischen Schutzschalters oder Schutzschaltrelais sein.Corresponding parts are provided with the same reference symbols in all figures. According to FIGS. 1 and 2, the current sensor 1 comprises a sensor winding or coil 2 which, like an excitation winding 3, is wound around a common coupling element 4. The cylindrical or rod-shaped and ferromagnetic coupling element 4 penetrates both windings 2, 3 in one piece. The sensor winding 2 consisting of a plurality of sensor windings 5 and the excitation winding 3, which may also consist of a plurality of windings 6, are arranged on the coupling element 4, forming a distance a. The coupling element 4 and the two windings 2, 3 are arranged in a sensor housing 7, the connection ends of the excitation winding 3 being guided inside the housing to corresponding connections 8a, 8b. The housing 7 can also be that of an electronic circuit breaker or circuit breaker relay.
Der Abstand b der Erregerwicklung 3 zum entsprechenden Kernende 4a des Koppel- elements 4 liegt vorzugsweise im Bereich weniger Millimeter, z. B. 2mm bis 5mm. Der Abstand b sollte dabei gleich der Breite c der Erregerwicklung 3 auf dem Koppelelement 4 sein. Der entsprechende Abstand d der Sensorwicklung 2 zum gegenüberliegenden Kernende 4b kann in der gleichen Größenordnung dimensioniert sein.The distance b between the excitation winding 3 and the corresponding core end 4a of the coupling element 4 is preferably in the range of a few millimeters, eg. B. 2mm to 5mm. The distance b should be equal to the width c of the excitation winding 3 on the coupling element 4. The corresponding distance d between the sensor winding 2 and the opposite core end 4b can be dimensioned in the same order of magnitude.
Der Außendurchmesser D des Koppelelementes 4 beträgt zwischen 1 mm und 10mm, vorzugsweise 2mm. Die Länge L des Koppelelementes 4 beträgt zwischen 2mm und 40mm, vorzugsweise 15mm. Die Masse des Koppelelementes beträgt zwischen 0,1g und 2g, vorzugsweise 0,2g.The outer diameter D of the coupling element 4 is between 1 mm and 10 mm, preferably 2 mm. The length L of the coupling element 4 is between 2mm and 40mm, preferably 15mm. The mass of the coupling element is between 0.1g and 2g, preferably 0.2g.
Die Sekundärwindungen 5 der Sensorwicklung 2 sind um das Koppelelement 4 unter Bildung eines Isolationsabstandes f herumgeführt. Dieser richtet sich wiederum nach den elektrischen Anforderungen. Der Isolationsabstand f wird durch ein geeignetes I- solationsmedium oder -material, vorzugsweise Luft, gebildet. Die Erregerwicklung 3 ist mit einem Isolationsabstand g um das Koppelelement 4 herumgeführt. Isolationsmedi- um ist hierbei ebenfalls vorzugsweise Luft. Die Abstände a, f und g sind im Wesentlichen abhängig von durch den bestimmungsgemäßen Einsatzzweck vorgegebenen e- lektrischen und/oder thermischen Isolationsanforderungen. Die Anzahl der Sekundärwindungen 5 zur Bildung der Sensorwicklung 2 beträgt im Ausführungsbeispiel 41A Auch kann die Sensorwicklung 2 mehr oder weniger Windungen, beispielsweise zwei bis zehn Windungen aufweisen. Die Anzahl der Erregerwicklungen beträgt im Ausführungsbeispiel VΛ. Auch hier können mehr oder weniger Erre- gei indungen 6 vorgesehen sein. Beispielsweise kann die Erregerwicklung 3 ein im Abstand g quer zum Koppelelement 4 verlaufender und den zu detektierenden Strom Ip führender Leiter sein. Die Erregerwicklung 3 ist die den Strom Ip führende Leitung selbst oder ein mit dieser verbindbarer Leitungsabschnitt.The secondary windings 5 of the sensor winding 2 are guided around the coupling element 4 to form an insulation distance f. This in turn depends on the electrical requirements. The insulation distance f is formed by a suitable insulation medium or material, preferably air. The excitation winding 3 is guided around the coupling element 4 with an insulation distance g. The insulation medium is also preferably air. The distances a, f and g are essentially dependent on the electrical and / or thermal insulation requirements specified by the intended use. In the exemplary embodiment 4, the number of secondary turns 5 for forming the sensor winding 2 is 1 A. The sensor winding 2 can also have more or fewer turns, for example two to ten turns. The number of excitation windings is VΛ in the exemplary embodiment. Here too, more or fewer excitation indications 6 can be provided. For example, the excitation winding 3 can be a conductor running at a distance g across the coupling element 4 and carrying the current Ip to be detected. The field winding 3 is the line carrying the current Ip itself or a line section which can be connected to it.
Bei einer Messung wird in Folge einer zeitlichen Änderung dlp/dt des Stromes Ip sowie aufgrund einer mittels des Koppelelementes 4 erreichten Konzentration des durch die schnelle Stromänderung erzeugten Magnetfeldes in der Sensorwicklung 2 eine Spannung induziert. Infolge einer Verstärkung durch die Magnetfeldkonzentration im ferro- magnetischen Koppelelement 4 ist an den Anschlussenden 2a, 2b der Sensorwicklung 2 ein Spannungssignal S mit relativ hohem Signalpegel abgreifbar. Die vom Stromsensor 1 detektierte Steigungsänderung d2lp/dt2 der schnellen Stromänderung resultiert in einem Signal S, das um so größer oder stärker ist, je steilflankiger die Stromänderung dlp/dt ist. Zeitgleich wird eine solche schnelle Stromänderung dlp/dt im oder mittels des Koppelelementes 4 gespeichert und damit zeitlich verlängert, wie dies in Fig. 4 veran- schaulicht ist.During a measurement, a voltage is induced in the sensor winding 2 as a result of a temporal change dlp / dt of the current Ip and on the basis of a concentration of the magnetic field generated by the rapid current change achieved by means of the coupling element 4. As a result of an amplification by the magnetic field concentration in the ferromagnetic coupling element 4, a voltage signal S with a relatively high signal level can be tapped at the connection ends 2a, 2b of the sensor winding 2. The gradient change d 2 lp / dt 2 of the rapid current change detected by the current sensor 1 results in a signal S which is greater or stronger the more steeply the current change dlp / dt is. At the same time, such a rapid current change dlp / dt is stored in or by means of the coupling element 4 and thus extended in time, as is illustrated in FIG. 4.
Fig. 4 zeigt schematisch im oberen Diagramm den Verlauf des erfassten Erregerstromes Ip über die Zeit t mit einer steilflankigen Stromänderung dlp/dt von einem vergleichsweise niedrigeren Stromwert Ipi zu einem vergleichsweise hohen Stromwert lp2. Die mittlere Darstellung in Fig. 4 zeigt das Signal S an den Eingängen Ei eines Analog/Digital-Wandlers (A/D-Wandler) 9 als Antwort auf die schnelle Stromänderung oder die Änderung der Steigung d2lp/dt2.4 shows schematically in the upper diagram the course of the detected excitation current Ip over time t with a steep-sided current change dlp / dt from a comparatively lower current value Ipi to a comparatively high current value lp 2 . The middle representation in FIG. 4 shows the signal S at the inputs Ei of an analog / digital converter (A / D converter) 9 in response to the rapid current change or the change in the gradient d 2 lp / dt 2 .
Fig. 3 zeigt die Abhängigkeit der Dämpfung θ des Signals S an den Eingängen Ei in Abhängigkeit von der Frequenz f bei einer Sensorwicklung 2 mit 4% Windungen und einer Erregerwicklung 3 mit VΛ Windungen sowie einer Länge L des Koppelelementes 4 von 15mm bei einem Außendurchmesser D von 2mm und einer Masse des Koppelelementes 4 von 0,2g . Das an der Sensorwicklung 2 abgreifbare Signal S wird dem Eingang Ei des zweckmäßigerweise als Komparator ausgeführten A/D-Wandler 9 einer Auswerteeinrichtung o- der -elektronik zugeführt. Dem weiteren Eingang E2 des Komparator und damit des als 1 bit-Wandler ausgeführten A/D-Wandlers 9 wird ein Referenzsignal URΘf in Form einer Spannung von z. B. 50mV bis 300mV zugeführt. Durch die A/D-Wandlung wird das Eingangs- oder Sensorsignal S auf die Referenz- oder Logikspannung URef bei einer Pulsweite Δt von z. B. 10ns bis 100ns normiert. Dadurch können die entsprechenden Ereignisse einfach verarbeitet werden.Fig. 3 shows the dependence of the attenuation θ of the signal S at the inputs Ei as a function of the frequency f for a sensor winding 2 with 4% turns and an excitation winding 3 with VΛ turns and a length L of the coupling element 4 of 15mm with an outer diameter D. of 2mm and a mass of the coupling element 4 of 0.2g. The signal S which can be tapped at the sensor winding 2 is fed to the input Ei of the A / D converter 9, which is expediently designed as a comparator, of an evaluation device or electronics. The further input E 2 of the comparator and thus of the A / D converter 9 designed as a 1 bit converter is a reference signal U RΘf in the form of a voltage of z. B. 50mV to 300mV supplied. The A / D conversion converts the input or sensor signal S to the reference or logic voltage U Ref with a pulse width Δt of z. B. normalized 10ns to 100ns. This makes it easy to process the relevant events.
Die Pulsdauer oder zeitliche Pulslänge Δt des Ausgangssignals P des A/D-Wandlers 9 wird insbesondere auch durch die Masse des Koppelelementes 4 und damit durch die Dämpfung θ bzw. Verstärkung V des Signals S bestimmt. Das infolge der A/D- Wandlung normierte Sensorsignal S am Ausgang A des Wandlers 9 ist in der unteren Darstellung in Fig. 4 veranschaulicht. Erkennbar ist, dass der A/D-Wandler bzw. Komparator 9 auf einen schnellen Stromanstieg dlp/dt mit einem zeitlich kurzen Impuls P der Impulslänge Δt reagiert.The pulse duration or temporal pulse length Δt of the output signal P of the A / D converter 9 is in particular also determined by the mass of the coupling element 4 and thus by the damping θ or amplification V of the signal S. The sensor signal S normalized as a result of the A / D conversion at the output A of the converter 9 is illustrated in the lower illustration in FIG. 4. It can be seen that the A / D converter or comparator 9 responds to a rapid current increase dlp / dt with a short-time pulse P of the pulse length Δt.
Für eine vereinfachte Darstellbarkeit der Ereignisse werden die Ausgangssignale oder Digitalwerte P des A/D-Wandlers 9 in einer diesem nachgeschalteten, nachfolgend als Signalverarbeitung bezeichneten Verarbeitungseinrichtung 10 aufsummiert. Deren Eingang Es ist mit dem Ausgang A des A/D-Wandlers 9 verbunden. Am Ausgang B der Signalverarbeitung 10 ist eine entsprechende Zahl oder Ereignisrate R in einem Zeitintervall abgreifbar. Die jeweiligen Ereignisraten R können - wie in den Fig. 5 und 6 ge- zeigt - graphisch dargestellt werden.For a simplified representation of the events, the output signals or digital values P of the A / D converter 9 are summed up in a processing device 10 connected downstream of this, hereinafter referred to as signal processing. Its input It is connected to the output A of the A / D converter 9. A corresponding number or event rate R can be tapped off at a time interval at output B of signal processing 10. The respective event rates R can - as shown in FIGS. 5 and 6 - be represented graphically.
Der A/D-Wandler 9 und die Signalverarbeitung 10 sind ebenfalls im Sensorgehäuse 7 angeordnet. Der Ausgang B der Signalverarbeitung 10 ist dabei an einen entsprechenden, analogen oder digitalen Anschluß 11 geführt, über den die Ereignisraten R aus- lesbar sind. Weitere Anschlüsse 12, 13 sind für die Versorgungsspannung UB bzw. Masse (Ground) vorgesehen. Fig. 5 zeigt mehrere Halbwellen eines Erregerstroms I mit Störungen SHF in Folge hochfrequenter Signalanteile. Diese, mit herkömmlichen Strommessungen bereits qualitativ nicht oder nur äußerst schwierig bzw. mit hohem messtechnischen Aufwand erkennbaren hochfrequenten Signalanteile werden vom Stromsensor 1 als solche detek- tiert. Die kurzzeitigen Impulse P werden in der Signalverarbeitung 10 für eine vereinfachte graphische Darstellbarkeit zur Ereignisrate R in einem Zeitintervall summiert.The A / D converter 9 and the signal processing 10 are also arranged in the sensor housing 7. The output B of the signal processing 10 is routed to a corresponding, analog or digital connection 11, via which the event rates R can be read out. Further connections 12, 13 are provided for the supply voltage U B or ground. FIG. 5 shows several half-waves of an excitation current I with SHF interference as a result of high-frequency signal components. These high-frequency signal components, which are not qualitatively or only extremely difficult to detect with conventional current measurements or can only be detected with high measurement complexity, are detected as such by the current sensor 1. The short-term pulses P are summed in the signal processing 10 for a simplified graphical representation to the event rate R in a time interval.
Fig. 6 zeigt ein mit herkömmlichen Mitteln erfasstes typisches Stromsignal Ip in Folge des Abschaltens eines Verbrauchers. Anhand des Verlaufes des Stromsignals Ip ist eine Abnahme des Strom Ip über die Zeit t in Folge des Abschaltens eines von mehreren Verbrauchern erkennbar. Das in dem unteren Teil des Diagramms dargestellte Signal zeigt die durch die Signalverarbeitung 10 ermittelte Ereignisrate R. Vom Stromsensor 1 detektiert wurde dabei der in dem Schalter für kurze Zeit erzeugte Lichtbogen.FIG. 6 shows a typical current signal Ip recorded by conventional means as a result of a consumer being switched off. The course of the current signal Ip shows a decrease in the current Ip over time t as a result of the switching off of one of several consumers. The signal shown in the lower part of the diagram shows the event rate R determined by the signal processing 10. The arc generated in the switch for a short time was detected by the current sensor 1.
Figur 7 zeigt eine alternative Ausführungsform des Stromsensors 1 , bei dem die Erregerwicklung 3 nicht neben, sondern über der Sensorwicklung 2 liegt. Diese wiederum umgibt das Koppelelement 4. Eine derartige geometrische Ausgestaltung des Stromsensors 1 hat den Vorteil, dass der Leiterquerschnitt der Erregerwicklung 3 vergleichsweise groß sein kann.FIG. 7 shows an alternative embodiment of the current sensor 1, in which the excitation winding 3 is not located next to but above the sensor winding 2. This in turn surrounds the coupling element 4. Such a geometric configuration of the current sensor 1 has the advantage that the conductor cross section of the excitation winding 3 can be comparatively large.
Anhand dieser Versuchsmessungen ist erkennbar, das mittels des erfindungsgemäßen Stromsensors 1 auch solche hochfrequente Stromänderungen eines zu erfassenden Stromes Ip zuverlässig erfasst werden, die bisher nur mit erheblichem messtechnischen Aufwand detektierbar wären. Da derartige, steilflankige Stromänderung insbesondere auch bei Störlichtbögen auftreten, die beispielsweise in Folge eines Potentialausgleichs zwischen zwei unterschiedliche Spannungspotentiale führenden und z. B. Isolationsdefekte aufweisenden benachbarten Leitern entstehen, eignet sich der Stromsensor 1 , insbesondere aufgrund dessen geringen Abmessungen und der einfachen Auswertung, vorteilhafterweise auch zur Detektion von Lichtbögen in Flugzeug-Bord netzen (arc tra- cking). BezugszeichenlisteOn the basis of these test measurements, it can be seen that the current sensor 1 according to the invention also reliably detects such high-frequency current changes in a current Ip to be detected that would previously have been detectable only with considerable expenditure on measurement technology. Since such steep-edged current changes occur in particular in the event of arcing faults, which lead, for example, as a result of equipotential bonding between two different voltage potentials and e.g. B. neighboring conductors having insulation defects, the current sensor 1 is particularly suitable, particularly because of its small dimensions and simple evaluation, also for detecting arcs in aircraft on-board networks (arc tracking). LIST OF REFERENCE NUMBERS
1 Stromsensor1 current sensor
2 Sensorwicklung2 sensor winding
2a,2b Anschlussende2a, 2b connection end
3 Erregerwicklung3 excitation winding
4 Koppelelement4 coupling element
4a,b Kernende4a, b core end
5 Sensorwindung5 sensor turn
6 Erregerwindung6 excitation turn
8a,b Anschluß8a, b connection
9 A/D-Wandler9 A / D converter
10 Signalverarbeitung10 signal processing
11-13 Anschluß11-13 connection
a-g Abstanda-g distance
Ip Erregerstrom lpi,P2 Stromverlauf t ZeitIp excitation current lpi, P2 current curve t time
A,B AusgangA, B output
D DurchmesserD diameter
E EingangE entrance
L LängeL length
R EreignisrateR event rate
P Ausgangssignal/DigitalwertP output signal / digital value
S SignalS signal
SHF Störanteil SHF interference component

Claims

Ansprüche Expectations
1. Stromsensor (1 ) zur Erfassung von Stromänderungen in Folge von Lichtbögen im Frequenzbereich zwischen 400kHz und 60MHz, mit einem ferromagnetischen s Koppelelement (4) und mit einer diesen mit einer Anzahl von Sekundärwindungen (5) umgebenden Sensorwicklung (2) sowie mit einer den Strom (Ip) führenden Erregerwicklung (3).1.Current sensor (1) for detecting current changes as a result of arcs in the frequency range between 400 kHz and 60 MHz, with a ferromagnetic coupling element (4) and with a sensor winding (2) surrounding it with a number of secondary windings (5) and with a Current (Ip) leading excitation winding (3).
2. Stromsensor nach Anspruch 1 ,0 dadurch gekennzeichnet, dass das Koppelelement (4) eine Masse von 0,1g bis 2g, vorzugsweise 0,2g, aufweist.2. Current sensor according to claim 1, 0 characterized in that the coupling element (4) has a mass of 0.1g to 2g, preferably 0.2g.
5 3. Stromsensor nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Erregerwicklung (3) eine viertel Windung (6) bis zehn Windungen (6) umfasst. 0 4. Stromsensor nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die Sensorwicklung (2) das Koppelement (4) unter Bildung eines Isolationsabstandes (f) umgibt. 5 5. Stromsensor nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Erregerwicklung (3) zur Sensorwicklung (2) beabstandet das Koppelelement (4) umgibt und dabei neben oder über der Sensorwicklung (2) angeordnet ist.0 6. Stromsensor nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass die Erregerwicklung (3) das Koppelelement (4) unter Bildung eines Isolationsabstandes (g) umgibt.5 3. Current sensor according to claim 1 or 2, characterized in that the excitation winding (3) comprises a quarter turn (6) to ten turns (6). 4. Current sensor according to one of claims 1 to 3, characterized in that the sensor winding (2) surrounds the coupling element (4), forming an insulation distance (f). 5. Current sensor according to one of claims 1 to 4, characterized in that the excitation winding (3) at a distance from the sensor winding (2) surrounds the coupling element (4) and is arranged next to or above the sensor winding (2) according to one of claims 1 to 5, characterized in that the field winding (3) surrounds the coupling element (4), forming an insulation distance (g).
7. Stromsensor nach einem der Ansprüche 1 bis 6, s dadurch gekennzeichnet, dass ein an den Anschlußenden (2a, 2b) der Sensorwicklung (2) abgreifbares Signal (S) direkt an einem Eingang (E-ι) eines Analog/Digital-Wandlers (9) zugeführt ist, an dessen weiteren Eingang (E2) ein Referenzsignal (l-Ref) geführt ist. 0 8. Stromsensor nach der Anspruch 7, gekennzeichnet durch einen Spannungswert des Referenzsignal (URef) von 1 mV bis 1000mV, vorzugsweise 50mV bis 300mV. 5 9. Stromsensor nach Anspruch 7 oder 8, dadurch gekennzeichnet, dass die Abtastzeit (Δt) des an den Anschlußeneden (2a, 2b) der Sensorwicklung (2) abgreifbaren Signals (S) 1 ns bis 1000ns, vorzugsweise 20ns, beträgt. 0 10. Stromsensor nach einem der Ansprüche 1 bis 9, gekennzeichnet durch ein Gehäuse (7) mit darin angeordnet einem mit der Sensorwicklung (2) ein- gangsseitig verbundenen Analog/Digital-Wandler (9). 5 11. Stromsensor nach Anspruch 10, gekennzeichnet durch eine dem Analog/Digital-Wandler (9) gehäuseintern nachgeschaltete Signalverarbeitung (10). o 12. Stromsensor nach einem der Ansprüche 1 bis 11 , dadurch gekennzeichnet, dass das Koppelelement (4) ein nicht geschlossener Zylinderkörper ist. 7. Current sensor according to one of claims 1 to 6, s characterized in that a signal (S) which can be tapped at the connection ends (2a, 2b) of the sensor winding (2) directly at an input (E-ι) of an analog / digital converter (9) is supplied, at whose further input (E 2 ) a reference signal (l- R ef) is carried. 8. Current sensor according to claim 7, characterized by a voltage value of the reference signal (U Ref ) of 1 mV to 1000mV, preferably 50mV to 300mV. 9. Current sensor according to claim 7 or 8, characterized in that the sampling time (Δt) of the signal (S) which can be picked up at the connection ends (2a, 2b) of the sensor winding (2) is 1 ns to 1000ns, preferably 20ns. 10. Current sensor according to one of claims 1 to 9, characterized by a housing (7) with an analog / digital converter (9) connected to the sensor winding (2) on the input side. 5 11. Current sensor according to claim 10, characterized by an analog / digital converter (9) inside the housing downstream signal processing (10). 12. Current sensor according to one of claims 1 to 11, characterized in that the coupling element (4) is a non-closed cylinder body.
13. Stromsensor nach einem der Ansprüche 1 bis 12, dadurch gekennzeichnet, dass das Koppelelement (4) ein langgestreckter Zylinderkörper ist.13. Current sensor according to one of claims 1 to 12, characterized in that the coupling element (4) is an elongated cylinder body.
s 14. Stromsensor nach einem der Ansprüche 1 bis 13, dadurch gekennzeichnet, dass das Koppelelement (4) aus ferromagnetischem Material besteht.s 14. Current sensor according to one of claims 1 to 13, characterized in that the coupling element (4) consists of ferromagnetic material.
15. Stromsensor nach einem der Ansprüche 1 bis 14,0 dadurch gekennzeichnet, dass der Außendurchmesser (D) des Koppelelementes (4) zwischen 1mm und 10mm, vorzugsweise 2mm, beträgt.15. Current sensor according to one of claims 1 to 14, characterized in that the outer diameter (D) of the coupling element (4) is between 1mm and 10mm, preferably 2mm.
16. Stromsensor nach einem der Ansprüche 1 bis 15,5 dadurch gekennzeichnet, dass das Koppelelement (4) eine Länge (L) von 2mm bis 40mm, vorzugsweise 15mm, aufweist. 16. Current sensor according to one of claims 1 to 15.5, characterized in that the coupling element (4) has a length (L) of 2mm to 40mm, preferably 15mm.
PCT/EP2005/003584 2004-04-07 2005-04-06 Current sensor WO2005098458A1 (en)

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