EP3014712B1 - Device for diverting earth currents, more particularly in wind turbines - Google Patents

Device for diverting earth currents, more particularly in wind turbines Download PDF

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Publication number
EP3014712B1
EP3014712B1 EP14734107.7A EP14734107A EP3014712B1 EP 3014712 B1 EP3014712 B1 EP 3014712B1 EP 14734107 A EP14734107 A EP 14734107A EP 3014712 B1 EP3014712 B1 EP 3014712B1
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EP
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Prior art keywords
carbon brush
metal
sliding contact
grounding
currents
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EP14734107.7A
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German (de)
French (fr)
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EP3014712A1 (en
Inventor
Manfred Faber
Bernd Kinast
Wolfgang Vesper
Dirk WOLTER
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Pantrac GmbH
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Pantrac GmbH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R39/00—Rotary current collectors, distributors or interrupters
    • H01R39/02—Details for dynamo electric machines
    • H01R39/18—Contacts for co-operation with commutator or slip-ring, e.g. contact brush
    • H01R39/26—Solid sliding contacts, e.g. carbon brush
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R39/00—Rotary current collectors, distributors or interrupters
    • H01R39/02—Details for dynamo electric machines
    • H01R39/18—Contacts for co-operation with commutator or slip-ring, e.g. contact brush
    • H01R39/20—Contacts for co-operation with commutator or slip-ring, e.g. contact brush characterised by the material thereof

Definitions

  • the invention relates to a carbon brush and a device for dissipating ground currents, in particular in wind turbines, of electric machines, comprising a grounding ring arranged on a rotor of the electric machine and a grounded sliding contact element which is in contact with the grounding ring.
  • Shaft voltages occur in large electrical machines in mains operation and in electrical machines in converter operation. As soon as these shaft voltages exceed a certain threshold value in the range of approximately 4 V (peak voltage), an electric breakdown occurs in the hydrodynamic, few ⁇ m thick, insulating oil film of the bearings. This electrical breakdown damages the running surfaces and leads to electrical erosion, which can significantly reduce the static bearing life.
  • the inverter In rotor-fed asynchronous generators, the inverter is located directly on the rotor via slip rings.
  • a so-called wave grounding known.
  • a grounding ring is arranged on the shaft, which is in contact with a sliding contact element, which is connected to ground.
  • the sliding contact element is known to be formed by a metal graphite brush or metal graphite natural graphite layer brush.
  • EP 1 662 649 A1 For example, a carbon brush comprising electrovalent or covalently bonded silver compounds is known.
  • the invention is therefore an object of the invention to provide a carbon brush and a device for the derivation of ground currents of the generic type, which is characterized by a simple structure and which is wear-resistant and ensures safe dissipation of high-frequency currents.
  • this object is achieved by a carbon brush with metal inclusion with the features mentioned in claim 1.
  • a wear of the earthing ring that is, the contact path coming into contact with the sliding contact, is reduced to an absolute minimum.
  • the addition of silver results in a uniform and low voltage drop at different operating and ambient conditions.
  • the carbon with metal inclusion with the bulk density according to the invention also has the advantages described above.
  • inventively found combination of a graphite with low density and constant, high coefficient of friction with low silver content in the structure is ensures that the elasticity and the coefficient of friction of the graphite material is maintained, the small amount of silver having only a small influence on the density, but at the same time causing a significant reduction of voltage peaks.
  • a safe dissipation of high-frequency currents from the shaft can take place.
  • the bearings are thus safely protected and thus have a large static life.
  • the object is further achieved by a device having the features mentioned in claim 2.
  • the sliding contact element has a carbon brush with a bulk density of 1.2 to 1.28 g / cm 3
  • the carbon brush has a metal deposit of silver, wherein the silver content is between 2 and 5% by weight with respect to the carbon brush.
  • This makes it possible to give the brush a high elasticity.
  • low bulk density was achieved that the carbon ensures a good electrical and mechanical contact of the sliding contact element with the earthing ring with metal insertion and has a high cross-country resistance with very constant coefficients of friction over the entire load spectrum.
  • the friction coefficient is for example in the range between 0.15 to 0.20.
  • the friction coefficient remains constant under different operating and environmental conditions. Maintenance intervals and thus the associated structure can be significantly reduced.
  • FIG. 1 shows a generally designated 10 device for deriving ground currents.
  • the device 10 includes a grounding ring 12 disposed on a shaft 14.
  • the shaft 14 is part of a rotor of an electrical machine, in particular a rotor-feeding asynchronous generator for wind turbines. Structure and mode of action of rotor-feeding asynchronous generators are well known, so that will not be discussed further in the context of the present description.
  • the grounding ring 12 is associated with a sliding contact element 16, which includes a carbon brush with metal insert 18.
  • the carbon brush with metal insert 18 is connected via a line 20 shown here to ground potential.
  • the carbon brush with metal insert 18 is in contact with the ground ring 12.
  • the carbon brush with metal insert 18 has a bulk density of 1.2 to 1.28 g / cm 3 .
  • the metal graphite brush 18 has a silver impregnation between 2 and 5% silver content. Due to the low density and the silver content, a small voltage drop, that is, a low contact resistance between the carbon brush with metal insert 18 and the grounding ring 12 is achieved in addition to the constant coefficient of friction.
  • a silver solution is injected into the carbon brush with metal deposit 18 of low bulk density, and then the silver is precipitated by a chemical-thermal process.
  • the silver is not melted for this purpose.
  • the silver content plays only a minor role for the current conductivity of the carbon brush with metal inclusion 18.
  • a 5% silver content in the metal graphite brush 18 causes the voltage drop across the device 10 to decrease by 50% and a 2.5% silver content causes the voltage drop in the device 10 to decrease by 25% over a non-silver impregnated carbon brush with metal deposition ,
  • the silver impregnation thus leads, in addition to the low bulk density of the carbon brush with metal insertion 18 already provided according to the invention, to further advantages. In particular, a high pulse current resistance is achieved.

Landscapes

  • Motor Or Generator Current Collectors (AREA)
  • Motor Or Generator Frames (AREA)
  • Wind Motors (AREA)
  • Control Of Eletrric Generators (AREA)

Description

Die Erfindung betrifft eine Kohlenstoffbürste und eine Vorrichtung zur Ableitung von Erdungsströmen, insbesondere in Windkraftanlagen, von elektrischen Maschinen, mit einem an einem Läufer der elektrischen Maschine angeordneten Erdungsring und einem mit Masse verbundenen Schleifkontaktelement, das mit dem Erdungsring in Kontakt steht.The invention relates to a carbon brush and a device for dissipating ground currents, in particular in wind turbines, of electric machines, comprising a grounding ring arranged on a rotor of the electric machine and a grounded sliding contact element which is in contact with the grounding ring.

Vorrichtungen der gattungsgemäßen Art sind bekannt.Devices of the generic type are known.

Bei großen elektrischen Maschinen im Netzbetrieb und bei elektrischen Maschinen im Umrichterbetrieb treten Wellenspannungen auf. Sobald diese Wellenspannungen einen bestimmten Schwellwert im Bereich von ca. 4 V (Spitzenspannung) überschreiten, kommt es im hydrodynamischen, wenige µm dicken, isolierenden Ölfilm der Lager zu einem elektrischen Durchschlag. Dieser elektrische Durchschlag schädigt die Laufflächen und führt zu einer Elektroerosion, die die statische Lagerlebensdauer deutlich reduzieren kann.Shaft voltages occur in large electrical machines in mains operation and in electrical machines in converter operation. As soon as these shaft voltages exceed a certain threshold value in the range of approximately 4 V (peak voltage), an electric breakdown occurs in the hydrodynamic, few μm thick, insulating oil film of the bearings. This electrical breakdown damages the running surfaces and leads to electrical erosion, which can significantly reduce the static bearing life.

Bei Umrichtermaschinen werden darüber hinaus Wellenspannungen durch die sogenannte Common Mode Spannung verursacht. Im Gegensatz zum Drehstromnetz heben sich die Spannungsvektoren der drei Phasen am Umrichterausgang nicht in jedem Zeitpunkt zu Null auf. Diese technologiebedingte Restspannung wird Common Mode Spannung genannt. Über einen Schwingkreis aus Leitungsinduktivität und Maschinenkapazitäten werden durch die Impulse der Common Mode Spannung Wellenspannungen als stark gedämpfte elektrische Schwingungen angelegt. Die Frequenzen dieser genannten Schwingungen liegen im Bereich von 30 bis 50 kHz und die Wiederholfrequenzen der einzelnen Spannungspeaks entsprechen der Umrichtertaktfrequenz im Bereich von 2 bis 3 kHz.In inverter machines wave voltages are caused by the so-called common mode voltage beyond. In contrast to the three-phase network, the voltage vectors of the three phases at the inverter output do not cancel each other at zero. This technology-related residual voltage is called common-mode voltage. Via a resonant circuit of line inductance and machine capacitance, shaft voltages are applied as strongly damped electrical oscillations by the pulses of the common mode. The frequencies of said oscillations are in the range of 30 to 50 kHz and the repetition frequencies of the individual voltage peaks correspond to the converter clock frequency in the range of 2 to 3 kHz.

Bei läuferspeisenden Windkraft-Asynchrongeneratoren liegt der Umrichter über Schleifringe direkt am Läufer.In rotor-fed asynchronous generators, the inverter is located directly on the rotor via slip rings.

Um die Lagerströme abzuleiten, das heißt diese nicht über die Lager zu führen, ist aus DE 10 2010 039 065 A1 eine sogenannte Wellenerdung bekannt. Hierbei wird auf der Welle ein Erdungsring angeordnet, der mit einem Schleifkontaktelement, das mit Erde verbunden ist, in Kontakt steht. Das Schleifkontaktelement wird bekanntermaßen von einer Metallgraphitbürste oder Metallgraphit-Naturgraphit-Schichtbürste gebildet.In order to derive the bearing currents, that is not to lead them over the bearings, is off DE 10 2010 039 065 A1 a so-called wave grounding known. In this case, a grounding ring is arranged on the shaft, which is in contact with a sliding contact element, which is connected to ground. The sliding contact element is known to be formed by a metal graphite brush or metal graphite natural graphite layer brush.

Es hat sich gezeigt, dass bei dem Einsatz der Metallgraphitbürsten oder Metallgraphit-Naturgraphit-Schichtbürsten ein relativ schneller Verschleiß an der Vorrichtung zur Ableitung von Erdungsströmen auftritt. Hierbei kommt es regelmäßig zu Anfleckungen auf den Erdungsringen und den Kontaktbahnen und zu Anbrennungen und Metallablagerungen auf den Erdungsringen und Kontaktbahnen. Es setzen Mikrolichtbögen zwischen dem Erdungsring und dem Schleifkontaktelement ein, die zu einer Erosion des Erdungsringes führen. Der hiermit einhergehende mechanische Verschleiß der Erdungsringe und der mit diesen in Kontakt stehenden Schleifkontaktelemente führt zu einem Anstieg des Spannungsabfalls über die Kontaktpartner. Hierdurch besteht die Gefahr des Ableitens der Wellenströme nicht über die Vorrichtung zum Ableiten von Erdungsströmen, sondern über die Lager, wodurch diese wiederum dem an sich zu verhindernden Verschleiß unterliegen.It has been found that with the use of the metal-graphite brushes or metal-graphite-natural graphite layer brushes, a relatively rapid wear on the device for discharging ground currents occurs. This regularly leads to stains on the earthing rings and the contact tracks and to burns and metal deposits on the grounding rings and contact tracks. There are micro-arcs between the ground ring and the sliding contact element, which lead to erosion of the earthing ring. The associated mechanical wear of the grounding rings and the sliding contact elements in contact with them leads to an increase in the voltage drop across the contact partners. As a result, the risk of discharging the wave currents does not exist on the device for discharging ground currents, but on the bearings, whereby these in turn are subject to the wear to be prevented per se.

Aus EP 1 662 649 A1 ist eine Kohlenstoffbürste bekannt, die elektrovalent oder kovalent gebundene Silberverbindungen umfasst.Out EP 1 662 649 A1 For example, a carbon brush comprising electrovalent or covalently bonded silver compounds is known.

Der Erfindung liegt daher die Aufgabe zugrunde, eine Kohlenstoffbürste und eine Vorrichtung zur Ableitung von Erdungsströmen der gattungsgemäßen Art zu schaffen, die sich durch einen einfachen Aufbau auszeichnet und die verschleißarm ist und eine sichere Ableitung von hochfrequenten Strömen gewährleistet.The invention is therefore an object of the invention to provide a carbon brush and a device for the derivation of ground currents of the generic type, which is characterized by a simple structure and which is wear-resistant and ensures safe dissipation of high-frequency currents.

Erfindungsgemäß wird diese Aufgabe durch eine Kohlenstoffbürste mit Metalleinlagerung mit den in Anspruch 1 genannten Merkmalen gelöst. Dadurch, dass die Kohlenstoffbürste mit Metalleinlagerung für ein Schleifkontaktelement, das mit einem Erdungsring einer elektrischen Maschine in einer Windkraftanlage in Kontakt steht, eine Rohdichte von 1,2 bis 1,28 g/cm3 aufweist und einen Silberanteil zwischen 2 und 5 Gew% in Bezug auf die Kohlenstoffbürste, wird vorteilhaft möglich, bereits vorhandene Vorrichtungen zur Ableitung von Erdungsströmen in Windkraftanlagen mit der erfindungsgemäßen Kohlenstoffbürste mit Metalleinlagerung auszustatten. Hierdurch wird die statische Lebensdauer der Lager der elektrischen Maschinen wesentlich verlängert.According to the invention this object is achieved by a carbon brush with metal inclusion with the features mentioned in claim 1. Characterized in that the carbon brush with metal insert for a sliding contact element, which is in contact with a grounding ring of an electric machine in a wind turbine, a bulk density of 1.2 to 1.28 g / cm 3 and a silver content between 2 and 5 wt% in With respect to the carbon brush, it is advantageously possible to equip existing devices for discharging grounding currents in wind power plants with the carbon brush according to the invention with metal deposition. As a result, the static life of the bearings of the electrical machines is significantly extended.

Ein Verschleiß des Erdungsringes, das heißt der mit dem Schleifkontakt in Kontakt kommenden Kontaktbahn, wird auf ein absolutes Minimum reduziert.A wear of the earthing ring, that is, the contact path coming into contact with the sliding contact, is reduced to an absolute minimum.

Durch den Zusatz von Silber stellt sich ein gleichmäßiger und geringer Spannungsabfall bei unterschiedlichen Betriebs- und Umgebungsbedingungen ein. Der Kohlenstoff mit Metalleinlagerung mit der erfindungsgemäßen Rohdichte weist ebenfalls die vorstehend beschriebenen Vorteile auf. Durch die erfindungsgemäß gefundene Kombination eines Graphit mit geringer Dichte und konstantem, hohen Reibwert mit geringem Silberanteil im Gefüge wird erreicht, dass die Elastizität und der Reibwert des Graphitwerkstoffes erhalten bleibt, wobei die geringe Silbermenge die Dichte nur gering beeinflusst, aber gleichzeitig eine deutliche Reduktion von Spannungspeaks bewirkt wird. Somit kann eine sichere Ableitung von hochfrequenten Strömen von der Welle erfolgen. Die Lager werden somit sicher geschützt und besitzen hiermit eine große statische Lebensdauer.The addition of silver results in a uniform and low voltage drop at different operating and ambient conditions. The carbon with metal inclusion with the bulk density according to the invention also has the advantages described above. By inventively found combination of a graphite with low density and constant, high coefficient of friction with low silver content in the structure is ensures that the elasticity and the coefficient of friction of the graphite material is maintained, the small amount of silver having only a small influence on the density, but at the same time causing a significant reduction of voltage peaks. Thus, a safe dissipation of high-frequency currents from the shaft can take place. The bearings are thus safely protected and thus have a large static life.

Insgesamt kann das Wartungsintervall zur Überprüfung beziehungsweise zum Austausch von Schleifkontaktelement und/oder Erdungsring deutlich verlängert werden. Insbesondere beim Einsatz von läufergespeisten Asynchrongeneratoren in Windkraftanlagen ergibt sich hiermit aufgrund der oftmals schwierigen Zugänglichkeit, beispielsweise bei Offshore-Anwendungen, ein deutlicher wirtschaftlicher Vorteil.Overall, the maintenance interval for checking or replacing the sliding contact element and / or earthing ring can be significantly extended. In particular, when using runner-fed asynchronous generators in wind turbines, this results in a significant economic advantage due to the often difficult accessibility, for example, in offshore applications.

Die Aufgabe wird ferner durch eine Vorrichtung mit den in Anspruch 2 genannten Merkmalen gelöst. Das Schleifkontaktelement, weist eine Kohlenstoffbürste mit einer Rohdichte von 1,2 bis 1,28 g/cm3 auf, und die Kohlenstoffbürste weist eine Metalleinlagerung von Silber auf, wobei der Silberanteil zwischen 2 und 5 Gew% beträgt in Bezug auf die Kohlenstoffbürste. Hierdurch ist es möglich, der Bürste eine hohe Elastizität zu verleihen. Durch diese, gegenüber den bekannten Metallgraphitbürsten niedrige Rohdichte wurde erreicht, dass der Kohlenstoff mit Metalleinlagerung eine gute elektrische und mechanische Kontaktierung des Schleifkontaktelementes mit dem Erdungsring sicherstellt und eine hohe Langlauffestigkeit mit sehr konstanten Reibkoeffizienten über das gesamte Belastungsspektrum aufweist. Der Reibungskoeffizient liegt beispielsweis im Bereich zwischen 0,15 bis 0,20. Der Reibungskoeffizient bleibt bei unterschiedlichen Betriebs- und Umgebungsbedingungen konstant. Wartungsintervalle und somit der damit verbundene Aufbau können deutlich reduziert werden.The object is further achieved by a device having the features mentioned in claim 2. The sliding contact element has a carbon brush with a bulk density of 1.2 to 1.28 g / cm 3 , and the carbon brush has a metal deposit of silver, wherein the silver content is between 2 and 5% by weight with respect to the carbon brush. This makes it possible to give the brush a high elasticity. By this, compared to the known metal graphite brushes low bulk density was achieved that the carbon ensures a good electrical and mechanical contact of the sliding contact element with the earthing ring with metal insertion and has a high cross-country resistance with very constant coefficients of friction over the entire load spectrum. The friction coefficient is for example in the range between 0.15 to 0.20. The friction coefficient remains constant under different operating and environmental conditions. Maintenance intervals and thus the associated structure can be significantly reduced.

Die Erfindung wird nachfolgend in einem Ausführungsbeispiel anhand der zugehörigen Zeichnung, die schematisch eine Vorrichtung zur Ableitung von Erdungsströmen zeigt, näher erläutert.The invention will be explained in more detail in an embodiment with reference to the accompanying drawing, which schematically shows a device for deriving ground currents.

Figur 1 zeigt eine insgesamt mit 10 bezeichnete Vorrichtung zur Ableitung von Erdungsströmen. Die Vorrichtung 10 umfasst einen Erdungsring 12, der auf einer Welle 14 angeordnet ist. Die Welle 14 ist Bestandteil eines Läufers einer elektrischen Maschine, insbesondere eines läuferspeisenden Asynchrongenerators für Windkraftanlagen. Aufbau und Wirkungsweise von läuferspeisenden Asynchrongeneratoren sind allgemein bekannt, so dass hierauf im Rahmen der vorliegenden Beschreibung nicht näher eingegangen wird. FIG. 1 shows a generally designated 10 device for deriving ground currents. The device 10 includes a grounding ring 12 disposed on a shaft 14. The shaft 14 is part of a rotor of an electrical machine, in particular a rotor-feeding asynchronous generator for wind turbines. Structure and mode of action of rotor-feeding asynchronous generators are well known, so that will not be discussed further in the context of the present description.

Dem Erdungsring 12 ist ein Schleifkontaktelement 16 zugeordnet, das eine Kohlenstoffbürste mit Metalleinlagerung 18 umfasst. Die Kohlenstoffbürste mit Metalleinlagerung 18 ist über eine hier gezeigte Leitung 20 mit Erdpotential verbunden.
Die Kohlenstoffbürste mit Metalleinlagerung 18 ist in Kontakt mit dem Erdungsring 12. Eine derartige Anordnung ist an sich bekannt.
Erfindungsgemäß ist vorgesehen, dass die Kohlenstoffbürste mit Metalleinlagerung 18 eine Rohdichte von 1,2 bis 1,28 g/cm3 aufweist. Ferner weist die Metallgraphitbürste 18 eine Silberimprägnierung zwischen 2 und 5 % Silberanteil auf.
Durch die geringe Dichte und den Silberanteil wird neben dem konstanten Reibungskoeffizienten auch ein geringer Spannungsabfall, das heißt ein niedriger Übergangswiderstand zwischen der Kohlenstoffbürste mit Metalleinlagerung 18 und dem Erdungsring 12 erzielt.
Zur Erzielung der Silberimprägnierung wird eine Silberlösung in die Kohlenstoffbürste mit Metalleinlagerung 18 mit der niedrigen Rohdichte injiziert und dann das Silber durch einen chemisch-thermischen Prozess ausgefällt. Das Silber wird hierzu nicht aufgeschmolzen. Der Silberanteil spielt für die Stromleitfähigkeit der Kohlenstoffbürste mit Metalleinlagerung 18 nur eine untergeordnete Rolle. Ein 5%iger Silberanteil in der Metallgraphitbürste 18 bewirkt das Absenken des Spannungsabfalls über der Vorrichtung 10 um 50 % und ein 2,5%iger Silberanteil bewirkt ein Absenken des Spannungsabfalls in der Vorrichtung 10 um 25 % gegenüber einer nicht mit Silber imprägnierten Kohlenstoffbürste mit Metalleinlagerung.
Die Silberimprägnierung führt somit zusätzlich zu der an sich schon erfindungsgemäß vorgesehenen niedrigen Rohdichte der Kohlenstoffbürste mit Metalleinlagerung 18 zu weiteren Vorteilen.
Insbesondere wird eine hohe Impulsstromfestigkeit erzielt. Bei Leerlauf beträgt diese beispielsweise 0 A/cm2, und bei Last 20 A/cm2. Durch die geringe Dichte besitzt die Kohlenstoffbürste mit Metalleinlagerung 18 eine hohe Elastizität, die zu einem konstanten Reibungskoeffizienten führt. Erzielbar ist die geringe Dichte beispielsweise durch einen geringen Aschegehalt, von beispielsweise 0,8 Gew% in der eingesetzten Kohlenstoffbürste mit Metalleinlagerung.
Zusammenfassend lässt sich also feststellen, dass durch den hochelastischen Bürstenwerkstoff für die Kohlenstoffbürste mit Metalleinlagerung 18 mit geringer Dichte ein stabiler Reibwert in Kombination mit dem geringen Silberanteil im Bürstenwerkstoff und ein geringer Spannungsabfall erzielt wird. Hierdurch wird ein wartungsarmes Laufverhalten der Vorrichtungsableitung von Erdungsströmen mit geringem Verschleiß der Kohlenstoffbürste mit Metalleinlagerung 18 und geringem Verschleiß des Erdungsringes 12 erhalten.The grounding ring 12 is associated with a sliding contact element 16, which includes a carbon brush with metal insert 18. The carbon brush with metal insert 18 is connected via a line 20 shown here to ground potential.
The carbon brush with metal insert 18 is in contact with the ground ring 12. Such an arrangement is known per se.
According to the invention, it is provided that the carbon brush with metal insert 18 has a bulk density of 1.2 to 1.28 g / cm 3 . Furthermore, the metal graphite brush 18 has a silver impregnation between 2 and 5% silver content.
Due to the low density and the silver content, a small voltage drop, that is, a low contact resistance between the carbon brush with metal insert 18 and the grounding ring 12 is achieved in addition to the constant coefficient of friction.
To obtain the silver impregnation, a silver solution is injected into the carbon brush with metal deposit 18 of low bulk density, and then the silver is precipitated by a chemical-thermal process. The silver is not melted for this purpose. The silver content plays only a minor role for the current conductivity of the carbon brush with metal inclusion 18. A 5% silver content in the metal graphite brush 18 causes the voltage drop across the device 10 to decrease by 50% and a 2.5% silver content causes the voltage drop in the device 10 to decrease by 25% over a non-silver impregnated carbon brush with metal deposition ,
The silver impregnation thus leads, in addition to the low bulk density of the carbon brush with metal insertion 18 already provided according to the invention, to further advantages.
In particular, a high pulse current resistance is achieved. At idling, this is for example 0 A / cm 2 , and at load 20 A / cm 2 . Due to the low density, the carbon brush with metal insert 18 has a high elasticity, which leads to a constant coefficient of friction. Achievable is the low density, for example, by a low ash content, for example, 0.8 wt% in the carbon brush used with metal insertion.
In summary, it can thus be stated that a stable coefficient of friction is due to the highly elastic brush material for the carbon brush with metal insert 18 with low density Combined with the low silver content in the brush material and a small voltage drop is achieved. As a result, a low-maintenance running behavior of the device discharge of grounding currents with little wear of the carbon brush with metal insert 18 and low wear of the grounding ring 12 is obtained.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

1010
Vorrichtungdevice
1212
Erdungsringgrounding ring
1414
Wellewave
1616
SchleifkontaktelementSliding contact element
1818
Kohlenstoffbürste mit MetalleinlagerungCarbon brush with metal insertion
2020
Leitungmanagement

Claims (2)

  1. A carbon brush with a metal insert (18) for a sliding contact element (16), which is able to be brought into contact with a grounding ring (12) of an electric machine in a wind turbine,
    characterised in that the carbon brush with a metal insert (18) has a gross density of 1.2 to 1.28 g/cm3 and a silver content between 2 and 5 wt% with respect to the carbon brush.
  2. A device for diverting grounding currents, in particular in wind turbines, of electric machines, comprising a grounding ring arranged at a rotor of the electric machine and a sliding contact element connected to ground, which is in contact with the grounding ring,
    characterised in that
    the sliding contact element (16) includes a carbon brush according to Claim 1.
EP14734107.7A 2013-06-25 2014-06-25 Device for diverting earth currents, more particularly in wind turbines Active EP3014712B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102013212062.1A DE102013212062B4 (en) 2013-06-25 2013-06-25 Device for discharging grounding currents, in particular in wind power plants
PCT/EP2014/063414 WO2014207047A1 (en) 2013-06-25 2014-06-25 Device for diverting earth currents, more particularly in wind turbines

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Publication Number Publication Date
EP3014712A1 EP3014712A1 (en) 2016-05-04
EP3014712B1 true EP3014712B1 (en) 2019-02-27

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US (1) US10109969B2 (en)
EP (1) EP3014712B1 (en)
JP (1) JP2016525329A (en)
CN (1) CN105340139B (en)
DE (1) DE102013212062B4 (en)
EA (1) EA030914B1 (en)
WO (1) WO2014207047A1 (en)

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US20160134072A1 (en) 2016-05-12
EP3014712A1 (en) 2016-05-04
WO2014207047A1 (en) 2014-12-31
EA201501138A1 (en) 2016-05-31
US10109969B2 (en) 2018-10-23
CN105340139A (en) 2016-02-17
JP2016525329A (en) 2016-08-22
CN105340139B (en) 2019-06-07
EA030914B1 (en) 2018-10-31
DE102013212062A1 (en) 2015-01-08
DE102013212062B4 (en) 2017-05-11

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