EP2715743B1 - Electric component for a high-voltage system - Google Patents

Description

• einen längs einer Achse erstreckten, auf Hochspannungspotential führbaren Stromleiter,
• einen am Stromleiter befestigten und den Stromleiter umfassenden starren Isolierkörper, enthaltend eine feste Polymermasse, die durch Aushärten einer vorgeformten, fliessfähigen Polymermasse gebildet ist,
• einen am Isolierkörper aussen befestigten, auf Erdpotial führbaren Montageflansch, und
• eine elektrisch leitend mit dem Stromleiter verbundene und an einem Ende des Stromleiters befestigte, haubenförmig ausgebildete Steuerelektrode, die bei Betrieb der Anlage das elektrische Feld zwischen dem Stromleiter und dem Montageflansch steuert.

The present invention relates to an electrical component for a high-voltage system, comprising in a coaxial arrangement:

• a current conductor extending along an axis and capable of being carried at high voltage potential,
• a rigid insulating body fastened to the current conductor and comprising the current conductor, containing a solid polymer mass, which is formed by curing a preformed, flowable polymer mass,
• a mounting flange attached to the outside of the insulating body, which can be guided to earth potential, and
• an electrically conductively connected to the current conductor and attached to one end of the current conductor, hood-shaped control electrode which controls the electric field between the current conductor and the mounting flange during operation of the system.

If such an electrical component is designed as a high-voltage bushing, after installation in the high-voltage system, it connects a current conductor of a first part of the system, which is electrically insulated with a solid, liquid or gaseous insulating agent from an encapsulation receiving the insulating agent, with a current conductor of a second part the plant. This current conductor is typically electrically insulated from the surrounding air, but can also be insulated with another insulating means which is contained in an encapsulation which accommodates the current conductor. If the electrical component is designed as a partition insulator of a gas-insulated, metal-enclosed switchgear, such a partition insulator separates two spaces of the installation filled with insulating gas from one another and connects two high-voltage current conductors provided in the two spaces.

The mechanical connection between the conductor of the electrical component and the two conductors of the parts to be connected, respectively. Rooms of the high-voltage system is an electrical field when the system is in operation exposed between the high-voltage conductors and the encapsulation, respectively. the mounting flange, which is electrically conductively connected to the encapsulation and is therefore largely kept at earth potential. The electrical component therefore has a control electrode which is guided cylindrically symmetrically around this current connection and which dielectrically shields this connection and uniformizes the electrical field.

STATE OF THE ART

An electrical component of the type mentioned in the introduction is designed, for example, as described in EP 1 284 484 B1 . EP 1 417 689 B1 . EP 1 771 866 B1 and WO 2009/053147 A1 , The implementation described is intended for installation in a generally metallic housing of an electrical high-voltage apparatus, for example in a transformer housing. In a coaxial arrangement, this bushing contains a current conductor that extends along an axis and can be guided at high voltage potential, a rigid insulating body fastened to the current conductor and comprising the current conductor, and a mounting flange that can be guided to ground potential on the outside of the insulating body.

A capacitor winding is integrated in the insulator. The mounting flange separates an airborne portion of the capacitor winding located above the mounting flange from a portion of the capacitor winding which is located below the mounting flange and which, after installation of the bushing in the apparatus, is placed in a non-air insulating material, typically oil or SF ₆ is. A region of these bushings exposed to the surrounding air each has a shield which acts as weather and radiation protection and which encloses the section of the capacitor winding located above the mounting flange. One only in EP 1 284 484 B1 The control electrode shown on the conductor of the bushing serves for the homogenization of the electric field at the aforementioned connection point to the conductor of the high-voltage apparatus.

The shielding can be as in EP 1 284 484 B1 and EP 1 771 689 B1 shown to be integrated in a porcelain insulator or made of silicone and on one fiber-reinforced plastic tube to be attached. But it can also - as in EP 1 417 689 B1 and WO 2009/053147 A1 described - be applied directly to the outer surface of the insulator receiving the capacitor winding, which extends between the mounting flange and a power connection of the bushing.

WO 2004/001783 A1 discloses a control electrode designed as a molded plastic part, which can be detachably attached to an electrical device, such as typically a vacuum interrupter, by means of a snap-in connection. To achieve a field-influencing effect, the material of the plastic molding is mixed with additives or the surface of the plastic molding is provided with a metallization. Information about the production of the plastic molded part or its deformation properties are not documented in this prior art.

PRESENTATION OF THE INVENTION

The object of the invention, as specified in the patent claims, is to create an electrical component of the type mentioned at the outset which is simple to manufacture and at the same time is distinguished by great operational reliability.

According to the present invention, an electrical component for a high-voltage system is provided which, in a coaxial arrangement, has a current conductor which extends along an axis and can be guided to high voltage potential, and a rigid insulating body which is fastened to the current conductor and comprises the current conductor and contains a solid polymer mass which is hardened by curing a preformed , flowable polymer mass is formed, a mounting flange attached to the outside of the insulating body, which can be guided to earth potential, and a hood-shaped control electrode which is connected in an electrically conductive manner to the current conductor and fastened to one end of the current conductor and which, when the system is in operation, generates the electrical field between the current conductor and the mounting flange controls.

According to the invention, the control electrode is non-detachably connected to the current conductor and has a dimensionally stable hood formed from the solid polymer mass during the preforming and curing of the flowable polymer mass and a coating of a hardened, electrically conductive lacquer is applied at least to the outwardly facing surface of the hood.

In a comparative example, the control electrode is designed to be elastically deformable and has a hood made of an elastomeric plastic and a coating of a hardened, electrically conductive or electrically non-conductive lacquer is applied at least to the outwardly facing surface of the hood.

The control electrode according to the invention can be produced with little effort and integrated into the electrical component. This considerably simplifies the manufacture, assembly and maintenance of the electrical component in accordance with the two alternative solutions. According to the invention, a hardened lacquer layer applied to the outside of the hood increases the dielectric strength of the component and accordingly also the operational reliability.

According to the invention, the insulating body and the control electrode are also produced by jointly preforming and curing the flowable polymer mass, typically in a casting mold. These two parts, which are important for the dielectric behavior of the component, therefore have largely identical material properties and thus contribute to increased operational reliability.

In the comparative example, the control electrode can yield when there is an undesirable mechanical load, such as an impact. In this way, an unintentional and possibly not immediately recognizable damage to the control electrode, for example during transport or during assembly, during operation or during maintenance of the electrical component, is largely avoided. Therefore, the control electrode of the comparative example increases the operational safety of the electrical component according to the invention.

In order to enable the component according to the invention to be manufactured particularly economically, the non-releasable connection can be embodied as an embedding in which one end of the current conductor carrying the control electrode is embedded in the hood produced by casting.

In the component according to the comparative example, the elastomeric plastic can be electrically conductive and contain at least one filler having electrically conductive particles. In this component, the elastomeric plastic can also be electrically non-conductive and the coating can be electrically conductive. In any case, the elastomeric plastic can contain silicone or EPDM.

In the component according to the comparative example, the control electrode can be detachably connected to the current conductor and can advantageously be designed as a snap or screw connection. Alternatively, the hood can be non-detachably connected to the current conductor and can advantageously be designed as an adhesive connection or as an embedding in which an end of the current conductor carrying the control electrode is embedded in the hood which is produced by casting or shrinking.

The hood and a shield applied to the insulating body can jointly contain an electrically non-conductive, elastomeric plastic, which is formed during the manufacture of the component by hardening a flowable starting mass introduced into a casting mold.

In the solution according to the invention or the comparative example, a capacitor winding can be embedded in the solid polymer mass with capacitor coatings which are electrically insulated from one another and which are kept at a distance from one another in the radial direction by an insulating film wound around the axis or by several layers of a thread-wound winding body guided around the axis.

The electrical component can be a bushing of the high-voltage system or a partition insulator of a gas-insulated and metal-encapsulated high-voltage system.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine Aufsicht auf eine längs einer Achse A erstreckte Ausführungsform einer als Durchführung ausgebildeten elektrischen Komponente nach der Erfindung, die rechts der Achse teilweise geschnitten dargestellt ist,

Fig.2

eine Vergrösserung eines umrandet dargestellten Teils der elektrischen Komponente nach Fig.1,

Fig.3

ein gemäss Fig.2 dargestelltes Vergleichsbeispiel,

Fig.4

ein gemäss Fig.2 dargestelltes Vergleichsbeispiel, und

Fig.5

ein gemäss den Figuren 2 bis 4 dargestelltes Vergleichsbeispiel.

The invention is explained in more detail below with the aid of drawings. Here shows:

Fig. 1

3 shows a plan view of an embodiment of an electrical component according to the invention, which is designed as a bushing and extends along an axis A and is shown partly in section to the right of the axis,

Fig. 2

an enlargement of a part of the electrical component shown with a border Fig. 1 .

Fig. 3

a according to Fig. 2 comparative example shown,

Figure 4

a according to Fig. 2 illustrated comparative example, and

Figure 5

one according to the Figures 2 to 4 Comparative example shown.

WAYS OF CARRYING OUT THE INVENTION

• einen längs der Achse A geführten Stromleiter 10 mit einem als erster Stromanschluss dienenden oberen Ende 11 und einem als zweiter Stromanschluss dienenden unteren Ende 12,
• einen am Stromleiter 10 befestigten und den Stromleiter umfassenden starren Isolierkörper 20,
• einen am Isolierkörper 20 befestigten und durch den Isolierkörper mit Abstand zum Stromleiter 10 gehaltenen Montageflansch 30, der beim Einbau der Durchführung in die Hochspannungsanlage mit einem isoliermittelgefüllten Metallgehäuse eines elektrischen Apparates, beispielsweise mit einem Transformatorgehäuse, verbunden ist,
• einen in den Isolierkörper 20 integrierten Kondensatorwickel 40,
• eine am unteren Ende 12 des Stromleiters 10 befestigte und mit dem Stromleiter 10 elektrisch leitend verbundene Steuerelektrode 50, und
• eine den Isolierkörper 20 umfassende Beschirmung 60, die sich in axialer Richtung vom Montageflansch 30 auf einen mit dem oberen Ende 11 des Stromleiters 10 elektrisch leitend verbundenen Flansch 11a erstreckt.

In all figures, the same reference symbols also designate parts with the same effect. The from the Figures 1 and 2 Apparent implementation contains the following parts in a coaxial arrangement:

• a current conductor 10 guided along the axis A with an upper end 11 serving as a first power connection and a lower end 12 serving as a second power connection,
• a rigid insulating body 20 fastened to the current conductor 10 and comprising the current conductor,
• a mounting flange 30 fastened to the insulating body 20 and held by the insulating body at a distance from the current conductor 10, which is connected to an insulating medium-filled metal housing of an electrical apparatus, for example a transformer housing, when the bushing is installed in the high-voltage system,
• a capacitor winding 40 integrated in the insulating body 20,
• a control electrode 50 attached to the lower end 12 of the current conductor 10 and electrically conductively connected to the current conductor 10, and
• a shield 60 comprising the insulating body 20, which extends in the axial direction from the mounting flange 30 to a flange 11a which is electrically conductively connected to the upper end 11 of the current conductor 10.

The lower end 12 of the current conductor 10, which is generally in the form of a tube or a round rod, can be connected in an electrically conductive manner to one end of a current conductor arranged in the aforementioned insulating-filled metal housing. Its upper end 11 can be electrically conductively connected to an outdoor-insulated high-voltage conductor. A then required shield 60 surrounding the insulating body 20, typically made of porcelain or a weather-resistant plastic, for example based on silicone, EPDM or cycloaliphatic epoxy, serves as weather and radiation protection.

The capacitor winding 40 has capacitor coatings 41 which are electrically insulated from one another and which are kept at a distance from one another in the radial direction. The insulating distance is achieved by means of an insulating foil 42 wound in the form of a spiral, which typically consists of paper and / or plastic, or by means of several layers of a thread-wound bobbin guided around the axis A. The capacitor winding 40 is used to control an electrical field, which is formed during the operation of the bushing between the current conductor 10, which is then at high voltage potential, and the mounting flange 30, which is then at the potential of the metal housing. The insulating film 42 and the capacitor coatings 41 of the capacitor winding 40 are embedded in a solid polymer mass 21 which generally contains filler and which is typically an epoxy filled with a mineral powder.

The control electrode 50 has a hood 51 made of plastic. Out Fig. 2 it can be seen that at least on the upward, downward and outward-facing, that is, at least on the entire outer surface of the hood 51, a coating 52 of a hardened lacquer is applied.

The control electrode 50 is located at the potential of the current conductor 10. This can be done on the one hand by an electrically conductive plastic forming the hood 51, for example by an electrically conductive particle such as graphite, metal. or metal oxide powder, filled polymer can be achieved. On the other hand, this can also be achieved in that the hardened lacquer forming the coating 52 is electrically conductive, regardless of whether the hood 51 is made of an electrically conductive or an electrically non-conductive plastic.

The coating 52 made of the electrically conductive or electrically non-conductive lacquer smoothes unavoidable surface roughness of the hood 51. A particularly fine control of the electrically conductive field that occurs during operation of the high-voltage system is achieved, which between the control electrode 50 and the mounting flange 30, respectively. the metal housing connected to this flange in an electrically conductive manner. In addition, such a coating has a polymeric matrix which protects the surface of the control electrode 50 from mechanical damage, such as scratching, and at the same time considerably reduces the undesired emission of electrons from the control electrode 50. If the coating 52 is formed by the hardened conductive lacquer, electrically conductive particles of the lacquer which are at high voltage potential are embedded in the polymer matrix and the undesired emission of electrons is then considerably reduced.

The hood is fastened in an axially symmetrical arrangement to the lower end of the current conductor 10 and, with its downwardly open, spherically curved wall, shields a current conductor connection with which the current conductor 10 with its lower end 12 connects to the end of the aforementioned current conductor, which is arranged in a metal housing filled with insulating material of the electrical apparatus is electrically connected.

In the embodiment according to the Figures 1 and 2 the control electrode 50 is non-detachably connected to the current conductor 10. The non-releasable connection is embodied as an embedding in which the end 12 of the current conductor 10 carrying the control electrode 50 is embedded in the hood 51 produced by casting.

The hood 51 is advantageously formed from an elastomeric plastic. The hood 51 can then be preformed by entering a flowable starting mass into a casting mold, which can also serve to manufacture the shield. In a subsequent crosslinking process, a hood 51 and optionally also a shield 60 are made in the casting mold achieved from the elastomeric plastic. The shield 60 is then direct (in Fig. 1 not shown) poured onto the rigid insulating body 20. If the flowable starting mass has a plastic containing electrically conductive particles, the hood 51 can be used as a control electrode 50 after applying a coating 52 made of a hardened, electrically non-conductive lacquer to the outwardly facing surface of the hood. If the hood 51 and the shielding have been formed together in a casting mold, then the hood 51 must be provided with a coating 52 of a hardened, electrically conductive lacquer, at least on the outward-facing surface. In the event of an undesirable mechanical load, such as an impact, the control electrode 50 can deform elastically. Damage to the control electrode during transport or during assembly of the component can thus be largely avoided. Suitable elastomers are primarily silicone and EPDM, but also elastomeric thermoplastics, such as thermoplastic polyurethane.

The hood 51 can, however, also be formed in a casting mold which forms the rigid insulating body 20 and the hood 51, and optionally also the shield 60 at the same time, into which, for example, in WO 2009/053147 A1 described, a winding body containing the current conductor 10 and the capacitor winding 40 is arranged and is impregnated with the flowable polymer mass under vacuum. The flowable polymer mass is subsequently cured in the casting mold to form the solid polymer mass 21 and thus also to form the rigid insulating body 20 and the dimensionally stable hood 51, optionally also the shield 60. A seat for the mounting flange 30 is machined into the molded body formed in this way, containing the current conductor 10, the insulating body 20, the capacitor winding 40, the hood 51 and possibly also the shield 60, and the cover 52 is at least formed on the outer surface of the hood 51, about with the help of the conductive varnish.

In the comparative examples according to the Figures 3 and 4 the connection between the lower end of the current conductor 12 and the control electrode 50 is detachable. As in Fig. 3 shown, the releasable connection is designed as a screw connection. It can then be seen that the control electrode 50 has a thread 54 which is screwed onto a counter thread 14 which fits into the End 12 of the conductor is molded. As in Figure 4 shown, the releasable connection can also be designed as a snap connection. It can then be seen that the control electrode 50 has an annular inner edge 53 which snaps into an annular groove 13 when the separately manufactured control electrode 50 is pushed on, which is formed in the lower end 12 of the current conductor.

From the comparative example in Figure 5 it can be seen that when the electrical component is designed as a partition insulator of a gas-insulated, metal-encapsulated high-voltage system, the current conductor 10 is fastened in the insulating body 20 analogously to the bushings described above and inserted into the metal encapsulation (not shown) with the aid of the mounting flange 30 and is thus held at a defined distance from the encapsulation . The control electrode 50 is fastened to the left end 12 of the current conductor 10 which is guided through the disk-shaped insulating body 20. At this end, the current conductor 10 can be electrically conductively connected, for example by plugging, to a current conductor of the high-voltage system arranged in the metal encapsulation and guided along the axis A. In a corresponding manner, a further control electrode can also be arranged on the right end, not shown, of the current conductor 10 led out of the pane 20. It can be seen that the control electrode 50 is connected to the current conductor 10 by snapping it on, that is to say releasably.

The control electrode 50 can, however, also be connected to the current conductor 10 in a non-detachable manner. The hood 51 is then produced when the flowable polymer mass intended for producing the insulating body 20 is cast. The solid polymer mass 21 of the hood 51 then embeds the end 12 of the current conductor 10 to form the non-releasable connection.

Depending on the requirement profile of the electrical component, the control electrode 50 can only on the lower resp. left 12 or at the top resp. right end 11 of the conductor 11 may be attached, or a control electrode may be attached to each of the two ends 11, 12.

REFERENCE SIGN LIST

10

Conductor

11, 12

Ends of the conductor

11a

flange

13

Ring groove

14

Mating thread

20th

Insulating body

21

hardened solid polymer mass

30

Mounting flange

40

Capacitor winding

41

Capacitor pads

42

Insulating film

50

Control electrode

51

Hood

52

coating

53

Inside edge

54

thread

60

Shielding

A

axis

Claims (6)

1. Electrical component for a high-voltage system, containing in a coaxial arrangement:

   a current conductor (10), which extends along an axis (A) and can be raised to high-voltage potential,

   a rigid insulating body (20), which is secured to the current conductor (10) and surrounds the current conductor, containing a solid polymer composition (21), which is formed by curing a preformed, flowable polymer composition,

   a mounting flange (30), which is secured externally on the insulating body (20) and can be raised to ground potential, and

   a cap-shaped control electrode (50), which is connected to the current conductor (10) in an electrically conductive manner and secured to one end (12) of the current conductor (10), and, during the operation of the system, controls the electric field between the current conductor (10) and the mounting flange (30),

   characterized in that the control electrode (50) is connected to the current conductor (10) in a non-detachable manner and has a dimensionally stable cap (51) made of the rigid polymer composition (21), which is produced during the preforming and curing of the flowable polymer composition, in that a coating (52) made of a cured, electrically conductive lacquer is applied at least to the surface of the cap (51) facing towards the outside; and in that the insulating body (20) and the control electrode (50) are produced by jointly preforming and curing the flowable polymer composition.
2. Component according to Claim 1, characterized in that the non-detachable connection is embodied as an embedding, in which one end (12) of the current conductor (10) that carries the control electrode (50) is embedded in the cap (51) that is produced by moulding.
3. Component according to either of Claims 1 and 2, characterized in that a capacitor winding (40) is embedded into the cured, solid polymer composition (21) of the insulating body (20), said capacitor winding having capacitor foils (41), which are electrically insulated from one another and which are held at a distance from one another in the radial direction by way of an insulating film (42) wound around the axis (A) or by a plurality of layers of a filament-wound winding body guided around the axis (A).
4. Component according to one of Claims 1 to 3, characterized in that the component is a bushing or a barrier insulator of the high-voltage system.
5. Component according to either of Claims 1 and 2, characterized in that the insulating body (20) and the control electrode (50) are produced by jointly preforming and curing the flowable polymer composition in a mould.
6. Component according to one of Claims 1 and 2 and 5, characterized in that the rigid insulating body (20) and the cap (51) and simultaneously a shield (60) are produced in a mould.

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