DE2816263A1 - Earth fault monitoring system for cable networks - uses fifth harmonic current detector with heavy fundamental suppression - Google Patents
Earth fault monitoring system for cable networks - uses fifth harmonic current detector with heavy fundamental suppressionInfo
- Publication number
- DE2816263A1 DE2816263A1 DE19782816263 DE2816263A DE2816263A1 DE 2816263 A1 DE2816263 A1 DE 2816263A1 DE 19782816263 DE19782816263 DE 19782816263 DE 2816263 A DE2816263 A DE 2816263A DE 2816263 A1 DE2816263 A1 DE 2816263A1
- Authority
- DE
- Germany
- Prior art keywords
- earth fault
- heavy
- cable networks
- current
- harmonic current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/50—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to the appearance of abnormal wave forms, e.g. ac in dc installations
- H02H3/52—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to the appearance of abnormal wave forms, e.g. ac in dc installations responsive to the appearance of harmonics
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
- H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Power Conversion In General (AREA)
Abstract
Description
Mit Wechselstrom gespeiste Schutzschaltung,Protective circuit supplied with alternating current,
insbesonders zur Erfassung von Erdschlüssen in Kabelnetzen Die Erfindung betrifft eine mit Wechselstrom gespeiste Schutzschaltung, insbesonders zur Erfassung von Erdschlüssen in Kabelnetzen unter Verwendung eines Stromwandlers, eines Frequenzfilters und eines Meßtriggers. Bei dieser wird aus einem Frequenzgemisch eine Oberwelle, insbes. die 5. Harmonische des Stromes herausgefiltert und mit Hilfe eines eßtriggers in ein Schaltsignal übergeführt. Die Schaltung findet insbesonders zur Erdschluß erfassung in Kabelnetzen Amfendungß da bekanntlich im Falle eines Erdschlusses die 5. Oberwelle in ganz charakteristischer Form hervortritt und somit ein deutliches Kriterium für einen Erdschluß darstellt.especially for the detection of earth faults in cable networks the The invention relates to a protective circuit fed with alternating current, in particular for the detection of earth faults in cable networks using a current transformer, a frequency filter and a measurement trigger. This is a mixture of frequencies a harmonic, especially the 5th harmonic of the current filtered out and with the help of an output trigger converted into a switching signal. The circuit takes place in particular for earth fault detection in cable networks Amfendungß as is well known in the case of a Earth fault, the 5th harmonic emerges in a very characteristic form and thus represents a clear criterion for an earth fault.
Die bisher bekannt gewordenen Schaltungen wiesen die Vemuendung eines einzigen Resonanzkreises auf und verzeichneten den Nachteil einer relativ geringen Unterdrückung der Grundwelle sowie einer sich daraus ergebenden geringen Empfindlichkeit. Daraus folgt, daß nur relativ große Oberwellenströne eindeutig erfaßt werden konnten.The circuits known so far showed the use of a single resonance circuit and recorded the disadvantage of a relatively low Suppression of the fundamental wave and a resulting low sensitivity. It follows that only relatively large harmonic waves could be clearly detected.
Aufgabe der Erfindung ist es, die Empfindlichkeit der Schaltung mit geringstem Aufwand durch bessere Ileraussiebung der Oberwellen zu erhöhen.The object of the invention is to increase the sensitivity of the circuit to increase the minimum effort through better filtering out of the harmonics.
Erfindungsgemäß besteht in der eingangs erwähnten Schutzschaltung das Frequenzfilter aus der Hintereinanderschaltung eines Parallelresonanzkreises, eines Serienkondensators und eines Brückengleichrichters.According to the invention, there is the protective circuit mentioned at the beginning the frequency filter from the series connection of a parallel resonance circuit, a series capacitor and a bridge rectifier.
Der Vorteil des erfindungsgemäßen Hochpaßfilters liegt in einer starken Unterdrückung der Grundwelle mit einem Faktor 3 bis 4, hauptsächlich durch den Einsatz eines einzigen zusätzlichen in Serie geschalteten Kondensators. Wollte man eine Unterdrückung der Grundwelle im gleichen Ausmaß nur mit Hilfe eines einzigen Resonanzkreises allein erzielen, müßte dieser extrem hohe Güte haben, wobei der Nachteil zu berücksichtigen ist, daß mit steigender Güte bezüglich der Filterungsfähigkeit des Resonanzkreises die Herstilungskosten exponentiell steigen. Als weiterer Nachteil muß die extrem hohe Selektivität genannt werden, die bei auch geringfügigen Schwankungen der Netzfrequenz und damit auch der herausgesiebten Oberwelle zu einer Herabsetzung der Empfindlichkeit führt.The advantage of the high-pass filter according to the invention is a strong one Suppression of the fundamental wave by a factor of 3 to 4, mainly through the use a single additional capacitor connected in series. If you wanted one Suppression of the fundamental wave to the same extent only with the help of a single resonance circuit achieve alone, this would have to have an extremely high quality, taking into account the disadvantage is that with increasing quality with respect to the filtering ability of the resonance circuit the manufacturing costs rise exponentially. Another disadvantage is the extreme high selectivity can be mentioned, even with slight fluctuations in the mains frequency and thus also the filtered out harmonic to a reduction of the sensitivity leads.
Die oben genannten Nachteile ließen sich durch die Hintereinanderschaltung zweier Resonanzkreise zwar beheben, jedoch ist die Realisierung überaus aufwendig.The above-mentioned disadvantages could be avoided by connecting them in series To fix two resonance circles, however, the implementation is extremely complex.
In einer weiteren Ausgestaltung des Brfindungsgedankens kann die induktive Komponente es Parallelschwingkreises in den Stromwandler einbezogen sein. In diesem Fall wird der Kern des im Eingangskreis befindlichen Stromwandlers mit einem Luftspalt versehen. (Resonanzwandler).In a further embodiment of the concept of invention, the inductive Component of the parallel resonant circuit must be included in the current transformer. In this Case becomes the core of the current transformer located in the input circuit with an air gap Mistake. (Resonance converter).
Durch diese Mafinahme wird der normalerweise vom Resonanzkreis getrennte Stromwandler i n einem Bauelement vereinigt, d. h. die Induktivität des Resonanzkreises und der Stromwandler sind ein Bauteil. Dadurch wir eine Einsparung an Bauteilen, Platz, an Material- und tiontagearbeitskosten erzielt Die nähere Erläuterung der Erfindung erfolgt an Hand der nachstehenden Zeichnung, welche die erfindungsgemäße Schaltung in schematischer Weise darstellt.By taking this measure, the is normally separated from the resonance circuit Current transformers combined in one component, d. H. the inductance of the resonance circuit and the current transformer are one component. As a result, we save on components, Space, material and labor costs achieved The more detailed explanation of the Invention is based on the following drawing, which shows the invention Represents circuit in a schematic manner.
Der Eingangskreis besteht aus dem Stromwandler T, der einen Parallelresonanzkreis speist. Dieser besteht aus der Drossel L und dem Kondensator CI. Die an diesem Parallelresonanzkreis entstehende Wechselspannung gelangt über den aus dem Kondensator C2, dem Brückengleichrichter G mit Bünde B bestehenden Hochpaß auf den Meßtrigger MT.The input circuit consists of the current transformer T, which is a parallel resonance circuit feeds. This consists of the choke L and the capacitor CI. The one on this parallel resonance circuit The alternating voltage that arises comes from the capacitor C2, the bridge rectifier G with frets B existing high pass to the measurement trigger MT.
Durch den Kondensator C2 erfolgt die zusätzliche Unterdrückung der Grundwelle mit einem Faktor 3 bis 4. Nach erfolgter Gleichrichtung im Gleichrichter G erfolgt im Meßtrigger MT die Überführung in ein Schaltsignal.The additional suppression of the Fundamental wave with a factor of 3 to 4. After rectification in the rectifier G is converted into a switching signal in the measurement trigger MT.
Claims (2)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT294977A AT351095B (en) | 1977-04-27 | 1977-04-27 | ALTERNATING CURRENT PROTECTION CIRCUIT, IN PARTICULAR FOR DETECTING EARTH FAULTS IN CABLE NETWORKS |
Publications (1)
Publication Number | Publication Date |
---|---|
DE2816263A1 true DE2816263A1 (en) | 1978-11-02 |
Family
ID=3542902
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
DE19782816263 Pending DE2816263A1 (en) | 1977-04-27 | 1978-04-14 | Earth fault monitoring system for cable networks - uses fifth harmonic current detector with heavy fundamental suppression |
Country Status (2)
Country | Link |
---|---|
AT (1) | AT351095B (en) |
DE (1) | DE2816263A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102014013417A1 (en) * | 2014-09-16 | 2016-03-17 | Forschungs- und Transferzentrum Leipzig e.V. an der Hochschule für Technik, Wirtschaft und Kultur Leipzig (FH) | Method and device for determining the earth fault current |
-
1977
- 1977-04-27 AT AT294977A patent/AT351095B/en not_active IP Right Cessation
-
1978
- 1978-04-14 DE DE19782816263 patent/DE2816263A1/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102014013417A1 (en) * | 2014-09-16 | 2016-03-17 | Forschungs- und Transferzentrum Leipzig e.V. an der Hochschule für Technik, Wirtschaft und Kultur Leipzig (FH) | Method and device for determining the earth fault current |
Also Published As
Publication number | Publication date |
---|---|
AT351095B (en) | 1979-07-10 |
ATA294977A (en) | 1978-12-15 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
OHJ | Non-payment of the annual fee |