EP0621611B1 - Support insulator - Google Patents

Support insulator Download PDF

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Publication number
EP0621611B1
EP0621611B1 EP94105324A EP94105324A EP0621611B1 EP 0621611 B1 EP0621611 B1 EP 0621611B1 EP 94105324 A EP94105324 A EP 94105324A EP 94105324 A EP94105324 A EP 94105324A EP 0621611 B1 EP0621611 B1 EP 0621611B1
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EP
European Patent Office
Prior art keywords
post insulator
surge arrester
insulator according
socket
measuring
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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.)
Expired - Lifetime
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EP94105324A
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German (de)
French (fr)
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EP0621611A1 (en
Inventor
Roland Höfner
Erwin Hartmann
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Siemens AG
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Siemens AG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T4/00—Overvoltage arresters using spark gaps
    • H01T4/08—Overvoltage arresters using spark gaps structurally associated with protected apparatus
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H01B17/005—Insulators structurally associated with built-in electrical equipment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
    • H01C7/12—Overvoltage protection resistors

Definitions

  • the invention relates to a post insulator with a capacitive voltage divider and surge arrester according to the preamble of claim 1.
  • a post insulator is known from DE-A-3,121,795.
  • a post insulator is used to firmly support a live part that is to be insulated against earth or other live parts.
  • the post insulator consists entirely or partially of cast resin.
  • capacitive voltage dividers have been used for years. These consist of the series connection of a post insulator with cast-in coupling capacitance and a further capacitance, which can be integrated in the connected measuring line. With this post insulator, the screw connection on the foot side, to which the measuring line is connected, must be attached to the grounded base in an insulated manner.
  • a post insulator is known from DE 31 21 795 A1, in which both the coupling capacitance and the surge arrester are installed in the interior of the post insulator. Furthermore, a complete evaluation circuit for evaluating the voltage signals, which can be obtained via the coupling capacitance, is integrated in a cartridge in the post insulator.
  • a cartridge disadvantageously takes up a relatively large amount of space, which leads to a reduction in the mechanical strength owing to the cavity in the post insulator which is necessary for integrating the cartridge.
  • the evaluation circuit is integrated in a fastening screw of the post insulator. Such a structure inevitably leads to a low mechanical strength of the fastening screw and thus to an unsafe fastening of the post insulator.
  • the invention is based on the object of specifying a post insulator with which, firstly, incorrect measurements are avoided as reliably as possible, secondly any overvoltage is kept away from the measuring line and thirdly simple manufacture and high mechanical strength are achieved.
  • the coupling capacitance, the surge arrester connected in series with the coupling capacitance and the connecting line connected between the coupling capacitance and surge arrester are poured into the casting resin are, with minimal space stress in the post insulator, it is ensured that the entire measuring line, which leaves the post insulator from the measuring socket, remains free of overvoltage even in the event of a breakdown in the coupling capacitance.
  • this construction ensures that the surge arrester is protected from environmental influences and also from mechanical and chemical damage.
  • the production is particularly simple and inexpensive because only the voltage divider, the surge arrester and the connecting line have to be kept essentially stationary in the casting mold, which is followed by the filling of the casting mold with casting resin.
  • the fastening bushing for fastening the post insulator can be grounded on a base in the foot part and conductively connected to the earth-side contact of the surge arrester.
  • the measuring socket is connected to the coupling electrode and installed in the foot part. This is the prerequisite for avoiding all climatic disturbances that could distort the measurement result with a special electrical connection element.
  • the operational reliability of the post insulator can be further improved if the surge arrester is provided with an electrically conductive shield in a further embodiment of the invention. That way shield the surge arrester against electromagnetic fields. In this way, undesired discharges inside the surge arrester can be avoided.
  • the figure shows a partially cut-out post insulator.
  • the insulating body 4 provided with outer ribs 2 can be seen.
  • it consists of a casting resin 6.
  • a metallic head bushing 12 is centered on the axis of symmetry 10 of the insulating body Threaded bore 14 cast.
  • a central foot bushing 18 with a threaded bore 20 and a lateral measuring bushing 22, which also carries a threaded bore 24, are cast in.
  • a surge arrester 26 - in the exemplary embodiment a gas discharge arrester - is screwed on.
  • the coupling electrode 28 is formed on the side facing the surge arrester 26 as a cap 30, which protects the surge arrester from electrical fields.
  • the head bushing 12 of the post insulator 1 carries a cylindrical wire grid electrode 32 centered on the axis of symmetry 10, which encloses the coupling electrode 28 at a greater distance.
  • the central coupling electrode 28 is connected within the insulating body to the measuring socket 22 via a connecting line 34.
  • the support insulator 1 stands on an earthed base frame 36, which is only indicated here. It is attached to this base frame 36 by means of screw 38 and washer 40 attached. The screw is passed through a corresponding hole 42 in the base frame and screwed onto the foot bushing 18 of the post insulator 1. Through a further hole 44 in the base frame, the angular cable connector 46 protrudes into the measuring socket 22. The cable plug 46 is screwed into an internal thread of the measuring socket 22. Between the housing of the cable connector 46 and the measuring socket, an annular pinch rubber 48 is inserted, which is pressed onto the foot part 16 of the insulating body 4 around the measuring socket 22 when the cable plug is screwed on.
  • the high voltage supporter 1 carries a high or medium voltage line (not shown) screwed to its head bushing and at the same time isolates it from one another the grounded base frame 36 on which it stands.
  • the support insulator 1 is screwed onto its base bushing 18 by means of the screw 38 and washer 40 on the base frame 36.
  • the foot socket is also connected in an electrically conductive manner to the grounded base frame via the screw and washer.
  • the cylindrical wire grid 32 fastened to the head bushing forms a capacitor together with the central coupling electrode 28. Via the connecting line 34 between the central coupling electrode 28 and the measuring socket 22, the capacitively absorbed displacement current can be passed on to a measuring or display device via the cable plug and the measuring cable.
  • the central coupling electrode 28 is insulated from the foot socket 18 and thus from the earth by the surge arrester 26, which in the exemplary embodiment is a gas discharge arrester.
  • the AC voltage generated in the central electrode 28 by the capacitive displacement current can be measured on a voltage meter or indicator, not shown here, connected to the cable connector 46. It can be used to read whether the high-voltage line is activated or not.
  • the installation of the surge arrester 26 in a shielding cap 30 of the central electrode 28 also ensures that no electric fields cause electrical discharges on the inner electrodes of the surge arrester.
  • the connection of the cable plug 46 into the measuring socket 22 and the encirclement of the connecting pin of the cable plug with a crimp rubber 48 means that the surroundings of the measuring socket 22 are shielded from climatic influences and no insulation problems can arise at this point either. The latter would be very dangerous because if the insulation failed, the central electrode 28 would be grounded. This would indicate that the high-voltage line was disconnected from the monitoring instrument (not shown here) connected to the measuring cable without this actually taking place.
  • the insulating body can also consist of a sintered ceramic.
  • the surge arrester can also be installed in a separate metallic dome or about half of it can be provided with an electrically conductive coating. It must be ensured that the coating does not short-circuit the two electrodes of the surge arrester at the operating voltage.

Abstract

In the case of known support insulators having a capacitive voltage divider and overvoltage suppressor, the problem, inter alia, arises of indicating the disconnection of the medium-voltage or high-voltage line which is held on the support insulator. In this case, climatic factors and other factors can adversely affect the insulation of the measurement line and a disconnection which has not been carried out can possibly be simulated. To this end, the invention provides that both the coupling capacitance and the overvoltage suppressor, which is connected in series with the coupling capacitance, are installed in the insulating body. The invention can be used for support insulators of any type. <IMAGE>

Description

Die Erfindung bezieht sich auf einen Stützisolator mit kapazitivem Spannungsteiler und Überspannungsableiter gemäß dem Oberbegriff des Anspruchs 1. Ein solcher Stützisolater ist aus DE-A-3.121.795 bekannt.The invention relates to a post insulator with a capacitive voltage divider and surge arrester according to the preamble of claim 1. Such a post insulator is known from DE-A-3,121,795.

Ein Stützisolator dient dazu, ein spannungsführendes Teil fest abzustützen, das gegen Erde oder andere spannungsführenden Teile zu isolieren ist. Der Stützisolator besteht ganz oder teilweise aus Gießharz.A post insulator is used to firmly support a live part that is to be insulated against earth or other live parts. The post insulator consists entirely or partially of cast resin.

In vielen Fällen ist es wünschenswert zu wissen, ob ein Leiter Spannung führt. Es soll sichergestellt werden, daß Geräte oder Anlagen erst geöffnet werden, wenn keine Berührungsgefahr mehr besteht. Dazu ist es notwendig, die Spannungsfreiheit festzustellen. Zu diesem Zweck werden bereits seit Jahren kapazitive Spannungsteiler verwendet. Diese bestehen aus der Reihenschaltung eines Stützisolators mit eingegossener Koppelkapazität und einer weiteren Kapazität, die in der angeschlossenen Meßleitung integriert sein kann. Bei diesem Stützisolator muß die fußseitige Verschraubung, an der die Meßleitung angeschlossen wird, isoliert zur geerdeten Unterlage befestigt werden.In many cases it is desirable to know whether a conductor is live. It should be ensured that devices or systems are only opened when there is no longer any danger of contact. To do this, it is necessary to determine the absence of voltage. For this purpose, capacitive voltage dividers have been used for years. These consist of the series connection of a post insulator with cast-in coupling capacitance and a further capacitance, which can be integrated in the connected measuring line. With this post insulator, the screw connection on the foot side, to which the measuring line is connected, must be attached to the grounded base in an insulated manner.

Es ist üblich, in die Meßleitung ein spannungsbegrenzendes Bauteil, einen sogenannten Überspannungsableiter, einzubauen. Dieser vermeidet, daß im nachgeschalteten Meßleitungsabschnitt und den angeschlossenen Bauteilen personengefährdende Überspannungen auftreten können, indem solche Spannungen gegen Erde abgeleitet werden.It is common to install a voltage-limiting component, a so-called surge arrester, in the measuring line. This prevents the occurrence of overvoltages which are hazardous to people in the downstream measuring line section and the connected components by discharging such voltages to earth.

Bei dieser Konstruktion ist es nachteilig, daß die spannungsführenden Bauteile vor dem Überspannungsableiter nicht vor Überspannung geschützt sind. Darüber hinaus ist eine äußerst aufwendige, isolierte Verschraubung am Fuß des Stützisolators anzubringen. Diese kann bei ungünstigen klimatischen Verhältnissen und/oder Fremdschichteinflüssen, d.h. oberflächlich anhaftenden Stoffen wie Ruß, Feuchtigkeit, Salzen und dergleichen, zu Isolationsproblemen führen und das Meßsignal kurzschließen, so daß ein Freischalten der Spannung am Anzeigegerät vorgetäuscht wird.With this construction, it is disadvantageous that the live components are not protected against overvoltage in front of the surge arrester. In addition, an extremely complex, insulated screw connection must be attached to the base of the post insulator. This can occur in unfavorable climatic conditions and / or foreign layer influences, ie substances adhering to the surface such as soot, moisture, salts and the like, lead to insulation problems and short-circuit the measurement signal, so that the voltage on the display device is simulated to be disconnected.

Aus der DE 31 21 795 A1 ist hierzu ein Stützisolator bekannt, bei dem sowohl die Koppelkapazität als auch der Überspannungsableiter im Inneren des Stützisolators eingebaut sind. Weiter ist eine vollständige Auswerteschaltung zur Auswertung der Spannungssignale, welche über die Koppelkapazität erhaltbar sind, in einer Patrone im Stützisolator integriert. Nachteiligerweise beansprucht eine derartige Patrone jedoch verhältnismäßig viel Raum, was aufgrund der zur Integration der Patrone erforderlichen Kavität im Stützisolator zu einer Verminderung der mechanischen Festigkeit führt. Dies ist auch dann der Fall, wenn, wie beschrieben, die Auswerteschaltung in eine Befestigungsschraube des Stützisolators integriert ist. Ein solcher Aufbau führt zwangsläufig zu einer geringen mechanischen Belastbarkeit der Befestigungsschraube und damit zu einer unsicheren Befestigung des Stützisolators.For this purpose, a post insulator is known from DE 31 21 795 A1, in which both the coupling capacitance and the surge arrester are installed in the interior of the post insulator. Furthermore, a complete evaluation circuit for evaluating the voltage signals, which can be obtained via the coupling capacitance, is integrated in a cartridge in the post insulator. However, such a cartridge disadvantageously takes up a relatively large amount of space, which leads to a reduction in the mechanical strength owing to the cavity in the post insulator which is necessary for integrating the cartridge. This is also the case if, as described, the evaluation circuit is integrated in a fastening screw of the post insulator. Such a structure inevitably leads to a low mechanical strength of the fastening screw and thus to an unsafe fastening of the post insulator.

Der Erfindung liegt die Aufgabe zugrunde, einen Stützisolator anzugeben, mit dem erstens Fehlmessungen in möglichst zuverlässiger Weise vermieden werden, zweitens jegliche Überspannung von der Meßleitung ferngehalten wird und drittens eine einfache Herstellung und eine hohe mechanische Festigkeit erreicht werden.The invention is based on the object of specifying a post insulator with which, firstly, incorrect measurements are avoided as reliably as possible, secondly any overvoltage is kept away from the measuring line and thirdly simple manufacture and high mechanical strength are achieved.

Diese Aufgabe wird durch die Merkmale des Anspruchs 1 gelöst. Weitere vorteilhafte Ausgestaltungen der Erfindung sind den Unteransprüchen zu entnehmen.This object is solved by the features of claim 1. Further advantageous embodiments of the invention can be found in the subclaims.

Dadurch, daß erfindungsgemäß die Koppelkapazität, der in Reihe zur Koppelkapazität geschaltete Überspannungsableiter sowie die zwischen Koppelkapazität und Überspannungsableiter angeschlossene Verbindungsleitung in das Gießharz eingegossen sind, wird bei minimaler Raumbeanspruchung im Stützisolator sichergestellt, daß die gesamte Meßleitung, die den Stützisolator ab der Meßbuchse verläßt, auch bei einem Durchschlag in der Koppelkapazität frei von Überspannung bleibt. Darüber hinaus ist durch diese Konstruktion gewährleistet, daß der Überspannungsableiter vor Umwelteinflüssen und auch vor mechanischen und chemischen Beschädigungen geschützt ist.Characterized in that according to the invention the coupling capacitance, the surge arrester connected in series with the coupling capacitance and the connecting line connected between the coupling capacitance and surge arrester are poured into the casting resin are, with minimal space stress in the post insulator, it is ensured that the entire measuring line, which leaves the post insulator from the measuring socket, remains free of overvoltage even in the event of a breakdown in the coupling capacitance. In addition, this construction ensures that the surge arrester is protected from environmental influences and also from mechanical and chemical damage.

Durch den geringen Eingriff in das Gefüge des Stützisolators wird eine besonders hohe mechanische Festigkeit erzielt. Zudem ist die Herstellung besonders einfach und kostengünstig, weil in der Gießform nur der Spannungsteiler, der Überspannungsableiter und die Verbindungsleitung im wesentlichen ortsfest gehalten werden müssen, woran sich das Auffüllen der Gießform mit Gießharz anschließt.Due to the slight interference in the structure of the post insulator, a particularly high mechanical strength is achieved. In addition, the production is particularly simple and inexpensive because only the voltage divider, the surge arrester and the connecting line have to be kept essentially stationary in the casting mold, which is followed by the filling of the casting mold with casting resin.

In besonders vorteilhafter Weiterbildung der Erfindung kann die Befestigungsbuchse zur Befestigung des Stützisolators auf einer Unterlage im Fußteil qeerdet und mit dem erdseitiqen Kontakt des Überspannungsableiters leitend verbunden sein. Diese Konstruktion bringt es mit sich, daß die aufwendige isolierte Verschraubung am Fuß des Hochspannungsableiters durch handelsübliche Bauteile ersetzt wird. Dadurch sind auch an dieser Stelle klimatische Störeinflüsse, die das Meßergebnis beeinträchtigen könnten, ausgeschaltet.In a particularly advantageous development of the invention, the fastening bushing for fastening the post insulator can be grounded on a base in the foot part and conductively connected to the earth-side contact of the surge arrester. This construction means that the complex, insulated screw connection at the base of the high-voltage arrester is replaced by commercially available components. As a result, climatic disturbances that could impair the measurement result are also eliminated at this point.

Es hat sich als recht zweckmäßig erwiesen, wenn in Ausgestaltung der Erfindung die Meßbuchse an der Koppelelektrode angeschlossen und im Fußteil eingebaut ist. Dies ist die Voraussetzung dafür, um mit einem speziellen elektrischen Anschlußelement alle klimatischen Störeinflüsse, die das Meßergebnis verfälschen könnten, zu vermeiden.It has proven to be quite expedient if, in an embodiment of the invention, the measuring socket is connected to the coupling electrode and installed in the foot part. This is the prerequisite for avoiding all climatic disturbances that could distort the measurement result with a special electrical connection element.

Die Betriebs zuverlässigkeit des Stützisolators läßt sich noch weiter verbessern, wenn der Überspannungsableiter in einer weiteren Ausgestaltung der Erfindung mit einer elektrisch leitfähigen Abschirmung versehen ist. Auf diese Weise läßt sich der Überspannungsableiter gegen elektromagnetische Felder abschirmen. Dadurch können unerwünschte Entladungen im Inneren des Überspannungsableiters vermieden werden.The operational reliability of the post insulator can be further improved if the surge arrester is provided with an electrically conductive shield in a further embodiment of the invention. That way shield the surge arrester against electromagnetic fields. In this way, undesired discharges inside the surge arrester can be avoided.

Ein Ausführungsbeispiel der Erfindung wird anhand einer Figur erläutert. Es zeigt:An embodiment of the invention is explained with reference to a figure. It shows:

Die Figur einen teilweise aufgeschnittenen Stützisolator.The figure shows a partially cut-out post insulator.

In der teilweise aufgebrochenen Darstellung der Figur des erfindungsgemäßen Stützisolators 1 erkennt man den mit äußeren Rippen 2 versehenen Isolierkörper 4. Er besteht im Ausführungsbeispiel aus einem Gießharz 6. Im Kopfteil 8 des Isolierkörpers 4 ist zur Symmetrieachse 10 des Isolierkörpers zentriert eine metallische Kopfbuchse 12 mit einer Gewindebohrung 14 eingegossen. Im Fußteil 16 des Isolierkörpers 4 ist eine zentrale Fußbuchse 18 mit einer Gewindebohrung 20 sowie eine seitliche Meßbuchse 22, die ebenfalls eine Gewindebohrung 24 trägt, eingegossen. Auf der der Kopfbuchse 12 zugewandten Seite der Fußbuchse 18 ist ein Überspannungsableiter 26 - im Ausführungsbeispiel ein Gasentladungsableiter - aufgeschraubt. Dieser trägt auf seiner, der Kopfbuchse 12 zugewandten Seite eine Elektrode 28 - auch Koppelelektrode genannt -, die zur Symmetrieachse 10 des Isolierkörpers 4 zentriert ist. Die Koppelelektrode 28 ist auf der dem Überspannungsableiter 26 zugewandten Seite als Kappe 30 ausgebildet, die den Überspannungsableiter vor elektrischen Feldern schützt. Die Kopfbuchse 12 des Stützisolators 1 trägt eine zur Symmetrieachse 10 zentrierte, zylinderförmige Drahtgitterelektrode 32, die die Koppelelektrode 28 im größeren Abstand umschließt. Die zentrale Koppelelektrode 28 ist innerhalb des Isolierkörpers über eine Verbindungsleitung 34 an die Meßbuchse 22 angeschlosssen.In the partially broken-open representation of the figure of the support insulator 1 according to the invention, the insulating body 4 provided with outer ribs 2 can be seen. In the exemplary embodiment, it consists of a casting resin 6. In the head part 8 of the insulating body 4, a metallic head bushing 12 is centered on the axis of symmetry 10 of the insulating body Threaded bore 14 cast. In the foot part 16 of the insulating body 4, a central foot bushing 18 with a threaded bore 20 and a lateral measuring bushing 22, which also carries a threaded bore 24, are cast in. On the side of the foot bushing 18 facing the head bushing 12, a surge arrester 26 - in the exemplary embodiment a gas discharge arrester - is screwed on. This carries on its side facing the head bushing 12 an electrode 28 - also called a coupling electrode - which is centered on the axis of symmetry 10 of the insulating body 4. The coupling electrode 28 is formed on the side facing the surge arrester 26 as a cap 30, which protects the surge arrester from electrical fields. The head bushing 12 of the post insulator 1 carries a cylindrical wire grid electrode 32 centered on the axis of symmetry 10, which encloses the coupling electrode 28 at a greater distance. The central coupling electrode 28 is connected within the insulating body to the measuring socket 22 via a connecting line 34.

Im Ausführungsbeispiel steht der Stützisolator 1 auf einem hier nur angedeuteten geerdeten Grundrahmen 36. Er ist an diesem Grundrahmen 36 mittels Schraube 38 und Unterlegscheibe 40 befestigt. Die Schraube ist durch ein entsprechendes Loch 42 im Grundrahmen hindurchgeführt und an der Fußbuchse 18 des Stützisolators 1 festgeschraubt. Durch ein weiteres Loch 44 im Grundrahmen ragt der winkelförmiger Kabelstecker 46 in die Meßbuchse 22 hinein. Der Kabelstecker 46 ist in einem Innengewinde der Meßbuchse 22 festgeschraubt. Zwischen dem Gehäuse des Kabelsteckers 46 und der Meßbuchse ist ein ringförmiges, den Steckerzapfen umschließendes Quetschgummi 48 eingesetzt, das bei aufgeschraubtem Kabelstecker an dem Fußteil 16 des Isolierkörpers 4 um die Meßbuchse 22 herum angedrückt wird.In the exemplary embodiment, the support insulator 1 stands on an earthed base frame 36, which is only indicated here. It is attached to this base frame 36 by means of screw 38 and washer 40 attached. The screw is passed through a corresponding hole 42 in the base frame and screwed onto the foot bushing 18 of the post insulator 1. Through a further hole 44 in the base frame, the angular cable connector 46 protrudes into the measuring socket 22. The cable plug 46 is screwed into an internal thread of the measuring socket 22. Between the housing of the cable connector 46 and the measuring socket, an annular pinch rubber 48 is inserted, which is pressed onto the foot part 16 of the insulating body 4 around the measuring socket 22 when the cable plug is screwed on.

Der Hochspannungsstützer 1 trägt eine an seiner Kopfbuchse festgeschraubte Hoch- oder Mittelspannungsleitung (nicht dargestellt) und isoliert sie zugleich gegenüber dem geerdeten Grundrahmen 36, auf dem er steht. Der Stützisolator 1 ist über seine Fußbuchse 18 mittels der Schraube 38 und Unterlegscheibe 40 auf dem Grundrahmen 36 festgeschraubt. Dabei ist zugleich auch die Fußbuchse über die Schraube und Unterlegscheibe mit dem geerdeten Grundrahmen elektrisch leitend verbunden. Das an der Kopfbuchse befestigte zylinderförmige Drahtgitter 32 bildet zusammen mit der zentralen Koppelelektrode 28 einen Kondensator. Über die Verbindungsleitung 34 zwischen der zentralen Koppelelektrode 28 und der Meßbuchse 22 kann über den Kabelstecker und das Meßkabel der kapazitiv aufgenommene Verschiebungsstrom an ein Meß- oder Anzeigegerät weitergeleitet werden.The high voltage supporter 1 carries a high or medium voltage line (not shown) screwed to its head bushing and at the same time isolates it from one another the grounded base frame 36 on which it stands. The support insulator 1 is screwed onto its base bushing 18 by means of the screw 38 and washer 40 on the base frame 36. At the same time, the foot socket is also connected in an electrically conductive manner to the grounded base frame via the screw and washer. The cylindrical wire grid 32 fastened to the head bushing forms a capacitor together with the central coupling electrode 28. Via the connecting line 34 between the central coupling electrode 28 and the measuring socket 22, the capacitively absorbed displacement current can be passed on to a measuring or display device via the cable plug and the measuring cable.

Bei der betriebsmäßig üblichen Spannung ist die zentrale Koppelelektrode 28 durch den Überspannungsableiter 26, der im Ausführungsbeispiel ein Gasentladungsableiter ist, gegenüber der Fußbuchse 18 und damit der Erde isoliert. Die in der zentralen Elektrode 28 durch den kapazitiven Verschiebungsstrom erzeugte Wechselspannung kann an einen am Kabelstecker 46 angeschlossenen, hier nicht dargestellten Spannungsmesser oder -anzeiger gemessen werden. An ihm kann abgelesen werden, ob die Hochspannungsleitung freigeschaltet ist oder nicht. Im Fall einer Überspannung an der zentralen Koppelelektrode 28, die etwa durch einen Durchschlag zwischen der zylinderförmigen Drahtgitterelektrode 32 und der Koppelelektrode 28 entstanden sein kann, wird diese Überspannung durch den Überspannungsableiter 26 auf die Fußbuchse 18 und über die Fußbuchse und die Befestigungsschraube 38 und Unterlegscheibe 40 im Fußteil 16 des Isolierkörpers 4 auf den geerdeten Grundrahmen 36 übertragen. Dadurch kann die Spannung an keinem Ort der Meßleitung und des Meßkabels einen Wert annehmen, der über jenem liegt, für die der Überspannungsableiter 26 eingestellt ist. Dadurch, daß der überspannungsableiter im Isolierkörper, im vorliegenden Fall ein Gießharz, eingegossen ist, ist er auch vor klimatischen Einflüssen und sonstigen mechanischen und chemischen Angriffen geschützt. Durch den Einbau des Überspannungsableiters 26 in einer Abschirmkappe 30 der zentralen Elektrode 28 ist zugleich auch gewährleistet, daß keine elektrischen Felder an den inneren Elektroden des Überspannungsableiters elektrische Entladungen hervorrufen. Auch der Anschluß des Kabelsteckers 46 in die Meßbuchse 22 und die Umschließung des Anschlußzapfens des Kabelsteckers mit einem Quetschgummi 48 bewirkt, daß die Umgebung der Meßbuchse 22 von klimatischen Einflüssen abgeschirmt ist und auch an dieser Stelle keine Isolationsprobleme entstehen können. Letzteres wäre sehr gefährlich, denn bei einem Versagen der Isolierung würde die zentrale Elektrode 28 geerdet werden. Dadurch würde an dem hier nicht weiter dargestellten, am Meßkabel angeschlossenen Überwachungsinstrument eine Freischaltung der Hochspannungsleitung angezeigt werden, ohne daß diese tatsächlich stattgefunden hat. Bei der bisher vorbekannten Befestigung des Meßkabels an der isolierten Befestigungsschraube im Stützerfuß konnten Isolationsschäden eine Freischaltung der Mittel- oder Hochspannungsleitung vortäuschen. Dadurch, daß die zentrale Koppelelektrode 28 unmittelbar am Überspannungsableiter 26 angeschlossen ist, ist bereits diese und damit auch die gesamte Verbindungsleitung 34 und das Meßkabel vor Überspannungen geschützt, so daß ein Überschleifen von unzulässigen Spannungen zuverlässig vermieden wird.At the voltage which is customary in operation, the central coupling electrode 28 is insulated from the foot socket 18 and thus from the earth by the surge arrester 26, which in the exemplary embodiment is a gas discharge arrester. The AC voltage generated in the central electrode 28 by the capacitive displacement current can be measured on a voltage meter or indicator, not shown here, connected to the cable connector 46. It can be used to read whether the high-voltage line is activated or not. In the event of an overvoltage at the central coupling electrode 28, which may have arisen as a result of a breakdown between the cylindrical wire grid electrode 32 and the coupling electrode 28, this overvoltage is transmitted through the surge arrester 26 to the foot socket 18 and via the foot socket and the fastening screw 38 and washer 40 transferred in the foot part 16 of the insulating body 4 to the grounded base frame 36. As a result, the voltage at any location on the measuring line and the measuring cable cannot assume a value which is higher than that for which the surge arrester 26 is set. Because the surge arrester is cast in the insulating body, in the present case a cast resin, it is also protected against climatic influences and other mechanical and chemical attacks. The installation of the surge arrester 26 in a shielding cap 30 of the central electrode 28 also ensures that no electric fields cause electrical discharges on the inner electrodes of the surge arrester. The connection of the cable plug 46 into the measuring socket 22 and the encirclement of the connecting pin of the cable plug with a crimp rubber 48 means that the surroundings of the measuring socket 22 are shielded from climatic influences and no insulation problems can arise at this point either. The latter would be very dangerous because if the insulation failed, the central electrode 28 would be grounded. This would indicate that the high-voltage line was disconnected from the monitoring instrument (not shown here) connected to the measuring cable without this actually taking place. With the previously known fastening of the measuring cable to the insulated fastening screw in the support foot, insulation damage could simulate an activation of the medium or high voltage line. Characterized in that the central coupling electrode 28 is connected directly to the surge arrester 26, this and thus the entire connecting line 34 and the measuring cable are already protected against overvoltages, so that a looping over of impermissible voltages is reliably avoided.

Alternativ wäre es auch möglich, statt des Gasentladungs-Überspannungsableiters einen anderen temperaturfesten Überspannungsableiter zu verwenden. In diesem Fall kann der Isolierkörper auch aus einer gesinterten Keramik bestehen. Statt des Einbaus des Überspannungsableiters in einer kalottenartigen Vertiefung der Koppelelektrode kann der Überspannungsableiter auch in einer separaten metallischen Kalotte eingebaut oder etwa zur Hälfte mit einem elektrisch leitenden überzug versehen werden. Dabei ist sicherzustellen, daß der Überzug nicht die beiden Elektroden des Überspannungsableiters bei der Betriebsspannung kurzschließt.Alternatively, it would also be possible to use another temperature-resistant surge arrester instead of the gas discharge surge arrester. In this case, the insulating body can also consist of a sintered ceramic. Instead of installing the surge arrester in a dome-like recess in the coupling electrode, the surge arrester can also be installed in a separate metallic dome or about half of it can be provided with an electrically conductive coating. It must be ensured that the coating does not short-circuit the two electrodes of the surge arrester at the operating voltage.

Claims (10)

  1. Post insulator (1) with coupling capacitance (28, 32) and surge arrester (26), which post insulator (1) is cast in whole or in part from casting resin, the coupling capacitance (28, 32) being encapsulated in the casting resin,
    characterized in that in addition the surge arrester (26) as well as a connecting lead (34) connected between the coupling capacitance (28, 32) and the surge arrester (26) are encapsulated in the casting resin, the connecting lead (34) being in contact with a separate, laterally disposed measuring socket (22) for connection to an external voltage measuring device.
  2. Post insulator according to claim 1,
    characterized in that the coupling capacitance (28, 32) comprises a rod-shaped coupling electrode (28), which is aligned with the axis of symmetry (10) of the insulating body (4), and a mesh electrode (32), which cylindrically encloses the coupling electrode and is connected in an electrically conductive manner to a screwed joint (14) disposed at the top part (8) of the post insulator (1).
  3. Post insulator according to claim 1 or 2,
    characterized in that a central fastening socket (18) for the fastening on a support (36) is earthed in the bottom part (16) of the post insulator (1) and conductively connected to the earth-side contact of the surge arrester (26).
  4. Post insulator according to claim 2 or 3,
    characterized in that the measuring socket (22) is connected to the coupling electrode (28) and installed in the bottom part (16).
  5. Post insulator according to one of claims 2 to 4,
    characterized in that the surge arrester (26) is disposed directly adjacent to the central coupling electrode (28).
  6. Post insulator according to one of claims 1 to 5,
    characterized in that the surge arrester (26) is provided with an electrically conductive screen (30).
  7. Post insulator according to one of claims 3 to 6,
    characterized in that the measuring socket (22) is disposed next to the central fastening socket (18) at the underside of the bottom part (16).
  8. Post insulator according to one of claims 1 to 7,
    characterized in that the measuring socket (22), once a male connector (46) has been attached, is protected from climatic influences by a pinching rubber (48) inserted between male connector (46) and measuring socket (22).
  9. Post insulator according to one of claims 2 to 8,
    characterized in that the end of the rod-shaped coupling electrode (28) directed towards the surge arrester (26) is designed as a screen 30 for the surge arrester (26).
  10. Post insulator according to one of claims 1 to 9,
    characterized in that an expulsion-type arrester is used as surge arrester (26).
EP94105324A 1993-04-20 1994-04-06 Support insulator Expired - Lifetime EP0621611B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4312685A DE4312685C2 (en) 1993-04-20 1993-04-20 Post insulator with built-in voltage divider and surge arrester
DE4312685 1993-04-20

Publications (2)

Publication Number Publication Date
EP0621611A1 EP0621611A1 (en) 1994-10-26
EP0621611B1 true EP0621611B1 (en) 1997-11-26

Family

ID=6485785

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94105324A Expired - Lifetime EP0621611B1 (en) 1993-04-20 1994-04-06 Support insulator

Country Status (7)

Country Link
EP (1) EP0621611B1 (en)
AT (1) ATE160644T1 (en)
DE (2) DE4312685C2 (en)
DK (1) DK0621611T3 (en)
ES (1) ES2109537T3 (en)
FI (1) FI941838A (en)
GR (1) GR3025606T3 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19522867B4 (en) * 1995-06-23 2005-12-22 Alstom Sachsenwerk Gmbh coupling isolator
DE19522868B4 (en) * 1995-06-23 2004-04-22 Alstom Sachsenwerk Gmbh Coupling isolator with a voltage connection at the top

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3121795A1 (en) * 1981-06-02 1982-12-16 Gossen Gmbh, 8520 Erlangen Coupling supporting insulator
DE8323693U1 (en) * 1983-08-17 1986-05-07 Siemens AG, 1000 Berlin und 8000 München Post insulator for high voltage
DE3610742A1 (en) * 1986-03-29 1987-10-08 Bbc Brown Boveri & Cie Supporting insulator
DE4111260A1 (en) * 1991-03-25 1992-10-01 Pfisterer Elektrotech Karl COMPONENT FOR HIGH VOLTAGE POWER SUPPLY SYSTEMS

Also Published As

Publication number Publication date
EP0621611A1 (en) 1994-10-26
ES2109537T3 (en) 1998-01-16
FI941838A0 (en) 1994-04-20
DE4312685C2 (en) 1997-05-28
ATE160644T1 (en) 1997-12-15
DK0621611T3 (en) 1998-08-10
DE4312685A1 (en) 1994-10-27
DE59404652D1 (en) 1998-01-08
FI941838A (en) 1994-10-21
GR3025606T3 (en) 1998-03-31

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