EP3472847A1 - Insulator arrangement for a high or medium voltage switchgear assembly - Google Patents

Abstract

The invention relates to an insulation arrangement (2) for a high or medium voltage switchgear assembly, comprising at least one axially symmetrical insulating structural element (4). The invention is characterised in that the structural element (4) comprises a conductive annular structure (8) arranged on its inner surface (6), and a conductive annular structure (16) arranged on its outer surface, these being insulated from one another by means of the insulating structural element.

Description

description

The invention relates to a method for producing a ceramic insulator according to the preamble of patent claim 1.

The insulating ability of solids such as alumina ceramics to withstand high stress is generally very high, but has its limits in the finite dielectric strength of solids. This also applies to high-voltage insulators, reindeer particular ceramic insulators for Central and Hochspannungsvakuumschaltröh-. Reason is the discharge structure within Isolato ^¬ reindeer, which is influenced by the defect density in the field direction. In this case, the dielectric strength, the breakdown of the solid state in the solid does not directly with the Iso ^¬ latorlänge, but it is proportional to the root of the insulator length. This has the consequence that it becomes increasingly difficult especially for high voltages above about 100 kV to effect the necessary withstand voltage of, for example vacuum interrupters ^¬ for the high voltage range, that is in a range of more than 72 kV. So far, this problem has been solved in particular with vacuum interrupters of the energy transmission and distribution technology in that instead of a single cylindrical insulator component with egg ^¬ ner greater length several shorter components are used, which by a suitable, vacuum-tight and mechanically stable connection technology, such as a braze, in axial

Direction are connected with each other. The composite of a plurality of such shorter insulators has a higher withstand voltage than an equal-length, one-piece insulator according to the above-described law of internal withstand voltage. Overall, this soldering process, however, is very costly, since a high technical complexity is required to produce the corresponding vacuum tightness for the connection. The object of the invention is to provide a technically cost-effective to manufacture ceramic insulator for a high or medium voltage switchgear.

The solution of the problem consists in an insulator assembly for a vacuum tube of a high or medium voltage switchgear with the features of claim 1 and in a Vaku ^¬ umröhre for a high or medium voltage switchgear with the features of claim 11.

The insulator arrangement according to the invention has at least one axially symmetrical insulating structural element, the invention being characterized in that the structural element has a conductive ring structure (8) arranged on its inner surface (6) and a conductive ring arranged on its outer surface Ring structure (14), which are isolated from each other by the insulating structural element.

The described ring structures form in the region of the structural element and also in the region of the entire

Isolator Arrangement Equipotential surfaces that increase the overall electrical strength of the insulator assembly.

In this context, equipotential surfaces are understood as meaning conductive layers on or between the structural elements, which have a higher electrical conductivity than the ceramic material of the structural elements and which are arranged perpendicular to the axis of symmetry and which define equipotential surfaces for axial electric fields. Thereby, the insulator assembly is electrically divided into short axial pieces, which increases the dielectric strength of the sub-section as well as the entire insulator.

In a further embodiment of the invention, a further outer ring structure is attached to an outer side of the structural element, with the ring structure in the interior of the structural element with respect to a solder on the ^{Längsach ¬} se of the structural element has an overlap. In this way, however, the equipotential surfaces thus formed are not formed by conductive layers between successive structural elements but as a region of greatly reduced axial electric field strength inside the insulator, the field strength reduction in the axial direction being due to the shielding effect of the conductive and internally applied conductive elements Coating is mediated. DA it has been found to be advantageous that the annular ^combustion structure with respect to the inside and outside substantially at the same height being ^¬ introduced to the axis of the structural element is, in that at least one solder precipitated on the longitudinal ^¬ axis of the structural element passing through both ring structures. As a result, the two ring structures are capacitively coupled to one another, so that a region with a low axial field strength results radially in the structural element. It may be appropriate to expand and better geometric design of the

Equipotential surfaces, that the inner and the outer ring ^¬ structure are arranged slightly offset with respect to the solder.

In a further embodiment, it is expedient that at least two structural elements are provided which are joined together along their end faces, wherein each of the at least two structural elements has at least one ring structure. Two ring structures have the advantage that reason ^¬ additionally the height of the insulator assembly grows and thus to a large extent also a higher electrical Durchschlags- is strength achieved when each of these structural elements comprising a further ring structure, thus a further increase in the breakdown field strength for the entire

Isolator arrangement realized. It has also been found that the structural element (4, 4 ^λ ) has an axial extent, which is between 10 mm and 200 mm, preferably between 20 mm and 80 mm, be ^¬ particularly preferably between 20 mm and 40 mm. At a Axial expansion in this size range is an optimum with respect to the dielectric strength on the one hand and the technical production possibilities of the structural element on the other hand. Structural elements are technically herzustel ^¬ len with a relatively reasonable cost, and further a high dielectric strength is realized, in particular by applying the ring structures described. Here, it is also advantageous if the spacing of the annular ^combustion structures, both the outer and the inner ring structure in an axial direction between 5 mm and 40 mm. Depending on the electrical conductivity of the ring structures, the effect of the equipotential surfaces is optimized in this distance range, so that there is a technically good relationship between insulation and charge removal.

It is also advantageous when a further working is coating provided on the structural member on its inside and / or on its outer side, which has a sheet resistance on ^¬ of between 10 ⁸ ohms 10 ¹² ohms, preferably between 10 ⁸ ohm 10 ¹⁰ ohms lies. The ring structure itself can be configured in various forms. In one embodiment, the ring structure consists of a metallic structure or of a conductive self-supporting structure, in particular in the form of a ring or in the form of a band or in the form of a film, which is applied to the corresponding surface of the structural element. On the other hand, it may be expedient to apply the ring structure in the form of a coating, in which case all common coating methods are expedient. In particular, the so-called plasma chemical vapor deposition, PCVD or CVD, but also the sputtering, vapor deposition or spraying and the doctoring and baking in the form of screen printing can be useful here. By applying a layer as described, the guide can adjust the surface resistance or resistance to the ring structure particularly well.

Another aspect of the invention is a vacuum interrupter for high and medium voltage applications which includes an isolator assembly according to claims 1-7.

Further embodiments and further features of the invention will be explained in more detail with reference to the following figures. Features with the same name but in different embodiments are provided with the same reference numerals. These are purely exemplary embodiments that do not limit the scope of protection.

Showing:

FIG. 1 shows a cross-sectional view of a vacuum interrupter with an insulator arrangement, wherein the left-hand part of the vacuum ^interrupter represents the state of the art.

FIG. 2 shows a three-dimensional representation of a structural element, each having a ring structure inside and outside,

Figure 3 is a cross-sectional view of the structural member of Figure 2, also cross-sectional view of the Strukturele ^¬ mentes of Figure 2 with a staggered arrangement of the ring structures,

 likewise cross-sectional representations of the structural element from FIG. 2 with additional second ring structure on the outside,

6 shows a structural element with ring structures and a

Surface coating of an outer surface, Figure 7 shows a structural element analogous to the representation in Figure 2 in cross-sectional view with shielding plates in the inner region

Figure 8 shows a cross section through an insulator assembly with two joined structural elements and

Figure 9 is a graphical representation of the relationship of

 Breakdown field strength and the height or thickness of the insulator material of the structural element.

In Figure 1 is a cross-sectional view of a typical vacuum interrupter 3 is shown, the figure 1 viewed from left to right on the left side of the prior

Technique corresponds and on the right side an example of an embodiment of the invention is shown. Basically, the vacuum interrupter 3 comprises an insulating space 25 in which two switching contacts 26 are arranged along a longitudinal axis 20 through the substantially rotationally symmetrical vacuum interrupter 3. At least one of the switching contacts 26 is with respect to the axis 20th

arranged translationally movable in the vacuum interrupter 3, so that the switching contact can be opened and closed. In the area to the left and right of the switch contacts (in a ^¬ installation position are these areas up and down bezüg ^¬ Lich of the heads of the switching contacts) are provided insulator arrangements. 2 This isolator assembly 2 is in particular in the art from the compound of a plurality of structural elements 4, which are joined to each other end face, wherein a corresponding place vacuum tightness ensuring end joining ^¬ process application.

The vacuum interrupter described here differs from the prior art in that ring structures 8 and 16, which are arranged in the inner region, are provided on the structural elements 4. Furthermore, it is expedient likewise in the outer region of the structural element 4 to have ring structures 16. bring to. The ring structures 8 and 16 are arranged such that they are located at the same height both inside and outside along the axis 20, essentially with respect to a longitudinal axis 20, so that at least a partial overlap exists. Furthermore, shielding plates 24 can be arranged on the structural elements 4 or on the insulator arrangement 2, which prevents a flashover between the contact 26 and the relatively conductive surfaces in the region of the ring structure 8.

It should be noted that both the ring structures 8 and / or 16 and the connection regions 27, which are usually equipped as conductive Lotstellen serve as the equipotential surfaces already described, which acts as a zone greatly reduced field strength in the axial direction and thus a breakdown of the Isolator 2 prevents.

The introduction of the ring structure increases the internal dielectric strength of a hollow cylindrical high-voltage insulator. In the case of the described vacuum interrupter, a part of the ultra-high-vacuum-tight envelope of the vacuum interrupter is simultaneously increased by the fact that along the inner (vacuum-side) and outer

Ceramic surfaces at shorter intervals conductive structures so the ring structures described here 8, 16 are applied to the ceramic of the structural element. These ring ^¬ structures 8, 16 have preferably a metallic or Annae ^¬ hernd metallic conductivity at least three toe ^¬ nerpotenzen is higher than the conductivity of the adjacent surface 10 of the structural element 4. In this way, with respect to by the ring structures 8, 16 of the defined electric fields equipotential surfaces 9, which penetrate the structural element 4, in particular a ceramic body, in the radial direction. As a result, the ceramic is electrically relieved in the interior of short axial portions of high axial field strengths and thus divided in the axial direction. In this way, the dielectric Festig ^¬ ness is not only along a section between two Equipotential surfaces but also greatly increased along the entire structural element 4. With the described arrangement of the ring structures on the structural element results in an extended range of reduced electric field strength, in which the probability of breakdown is statistically minimized.

Basically, in this description, the starting point is essentially ceramic structural elements 4, which are preferably in the form of a hollow-cylindrical insulator structure, however an embodiment of the structural element 4 is provided by insulators based on polymers or composite materials, eg glass-reinforced or filled with quartz or other ceramic powders Epoxy resin also appropriate. Also deviating from the symmetrical circular cross sections such as ellipses or polygons are possible ^¬ Liche solutions.

One advantageous effect of the invention is, inter alia, that the subdivision of a conventionally long ceramic structural element 4 by the application of conductive equipotential surfaces 9 in the form of the described ring structures 8, 16 in the inner and preferably outer region of the structural element 4 either already during manufacture on the ceramic body to integrate or subsequently on this

Structure is to apply. As will be explained in more detail here with reference to FIG. 9, a single structural element having a predetermined height has a higher electrical strength than the same structural element without the conductive ring structures 8, 16 described by this measure.

As a result, the manufacturing cost of the entire

Isolatoranordung, possibly depending on the required insulation, significantly reduced because fewer separation points or connections 27 are required. It can be enough, depending on the requirement, instead of three structural elements to one

Assemble insulator assembly 2, only two structural elements apply. This establishes a connection 27. saves a particularly high proportion of the total cost in the production of the insulator assembly 2. In addition, thus a source of error in a possible leakage of the vacuum interrupter 3 is eliminated.

The ring structure which acts in an area in the interior of the ceramic is equivalent to an equipotential surface 9, is thus not as physically be introduced layer as Example ^¬, the compound 27 is configured, but as functionally equivalent but much more easily applied Zone With a significantly increased electrical conductivity with respect to the adjacent surface 10 of the structural element 4. It can be formed along a structural element in the axial direction (along the longitudinal axis) a plurality of areas with the ring structures, so as to further shorten the burdened with high electrical field strengths Isolatorteillängen without the electric strength at the Oberflä ^¬ surface of the insulator body in an axial direction to impair ^¬ gen.

The preparation of the ring structures described can be done by different methods and shapes. Beispielswei ^¬ se is the application of the ring structures 8, 16, expediently by a metallic conductive layer, for example in the form of burned-metallic or metal-oxide layers. suitable

Metal oxides or mixtures are, inter alia, those which are also used for the metallization of ceramics e.g. be used according to the so-called Mo / MnO method, or which are used for the reactive solder joint of metallic and ceramic components.

In particular with regard to the outer ring structures 18, it is particularly suitable to apply interrupted ring structures, both ring structures 16 and ring structures 8, which have, for example, interrupted ribbons, staggered bands or rings or points which are adjacent but not touching. Also possible are layers which can be configured by sputtering, vapor deposition, spraying or CVD or PCVD method as metallic metal oxide layers or as metal borides, carbides or metal nitrides. It is also possible to apply organically bound, conductive lacquers which are freed from the organic phase by thermal treatment. Also graphitic or graphite-containing layers, for example by the Aquadag method are suitable to represent the corresponding ring structures. This also applies to graphite structures generated by entspre ^¬ sponding abrasion of a carbon source / graphite source who ^¬. The method described is an example of possible representations of the described ring structures 8 and 16.

In this case, the corresponding ring structures 8, 16 on the structural elements 4, in its arrangement in the

Insulator assembly 2 are provided with the so-called shield systems or shield plates 24, as shown for example in Figure 7 but also in the figure 1. This results in an additional function, which can, for example, since there are ^¬ rin that these shielding plates 27 is a shielding of the ceramic surface prior to vapor deposition of metal vapor generated from the switching arc.

The ring structures 8, 16 need not necessarily be configured by ^¬ continuous, ie be carried out continuously, but can also be as flat structures structures consisting of ras terförmig applied closely adjacent conductive structural, for example dots or dashes are executed. Such layers are particularly advantageous to produce by screen printing methods such as doctoring.

2 shows a three-dimensional representation of a structural given turelementes 4, which is substantially rotationssymmet ^¬ driven, in this case shown in cylinder form and the ring structure has an inner surface 6 8 ^¬ which is shown in phantom in Figure 2 and at one ner outer side, an outer ring structure 16 is arranged. As can be seen in FIG. 3, which shows a cross-sectional view of FIG. 2, the ring structures 16 and 8 extend at the same height with respect to an axial extent of the structural element 4. That means a solder 18, which is precipitated on the axis 20, passes through both the inner ring ^¬ structure 8 and the outer ring structure 16 and this ^{¬ at} least in a coverage area.

In Figures 4 and 5 ring structures are 8 and 16, in which it does not -prozentigen to a 100% Überde ^¬ is discovered in the axial direction, wherein these ring structures are slightly shifted 8 and 16 axially toward each other, but still comes to a coverage area , In the Figure 5 4 ^¬ two ring structures 16 are applied on the outside of the structural element, wherein both ring structures 16 preferably in turn have an overlap in the axial direction with the annular structure 8 in the inner portion 6 of the structural element. 4 That is, a Lot 18, on the ^axle 20 ^¬ can be placed so that it passes through both Ringstruktu ^¬ ren 8, 16.

In Figure 6, a structural element 4 is shown, comprising an analog embodiment, to the structural element 4 in figure 3, but the too ^¬ additional surface coating has on its outer surface 22, which is preferably a sheet resistance of typically 100 megohms per square having what a bad conductor or, in other words, does not represent an insulator. In this way acts on this surface 22 both an ohmic and non-linear current voltage characteristic. This is used for electric field control on the surface and to reduce the charging of the surface with electric charges. As a result, particularly stress-resistant structural elements 4 can be produced. Alternatively, the high surface resistivity conductive coating between 10 ⁸ ohms and 10 ¹² ohms may also be deposited on the inside or both sides of the ceramic. The resistance layer can be located below the ring Structures 8, 16 may be applied as in another embodiment, the cover over the ring structures 8, 16 extend. In the figures 2 to 7 insulator assemblies 2 are shown, which consist of only one structural element 4. For the sake of clarity, these insulator arrangements 2 are designed here only in the middle region with ring structures 8, 16 in this exemplary embodiment. However, the ring structures 8, 16 have a typical distance in the axial direction, which is between 10mm and 40mm. A typical structural element 4, as shown in Figu ^¬ ren 2-7, 8 and 16 can thus have a plurality of ring structures on the inside and the outside, which lead to the above described advantageous, inner electrical effects. In this respect, FIGS. 2-7 have a purely exemplary character and serve in particular to illustrate the arrangement of the ring structures 8 and 16 in general. FIG. 8 shows an insulator arrangement 2 which is composed of two structural elements 4. The structural ^¬ turelemente 4 in Figure 8 are joined by the connecting end face 27th In this case, the connection 27 likewise consists of a metallically conductive layer and likewise represents an equipotential surface 9.

By applying the ring structures 8 and 16 additional equipotential surfaces 9 are introduced into the insulator structure 2, which have the positive electrical properties already described. Referring to FIG. 9, it can be seen that in a relationship between the breakdown field strength 28 plotted on the Y axis and the height or thickness of the ceramic insulator applied on the X axis and denoted by the reference numeral 29 is a wurzelförmiger course, which is represented by the curve 30. That is, at a height of, for example, 5 units of length of a structural element 4, a dielectric strength, in this example of 60 kV, is achieved. At 10 length units of the same material and the same thickness only about 90 kV dielectric strength are generated. This means that either the structural element 4 has to be designed to be very long in order to achieve a high dielectric strength, or several structural elements 4, which each have the corresponding equipotential surfaces 9, have to be joined together. The

Equipotential surfaces 9 are shown in the conventional construction of vacuum interrupters 3 and insulator arrangements 2 for vacuum interrupters by the solder joints. Due to the additional ring structures 8 and 16 described here, on the one hand a shortening of the distances of

Equipotential surfaces 9 causes so that, for example, at a distance of 5 units of length between the ring structures, the dielectric strength of 60 kV can be achieved. On the other hand, in the ceramic region between the ring structures 8, 16, a virtual equipotential surface 9 ^{λ is} introduced, which causes a virtual Verür ^¬ tion of the ceramic without soldering. In 2x5 units of length along the same structural element while a dielectric strength of 120 kV can be achieved already with a forth ^¬ kömmliches structural element according to the prior art for the same example would yield only 90 kV electric strength. This causes the entire length of the

Insulator assembly 2 can be significantly reduced, which on the one hand represents a significant reduction of the manufacturing process cost, which in turn is reflected in a significant cost reduction with less space of the vacuum interrupter 3.

Claims

claims 1. insulator arrangement (2) for a high or medium voltage switchgear with at least one achsensymmetri- see insulating structural element (4), characterized in that the structural element (4) arranged on its inner surface (6) conductive Ringstruk ^¬ tur (8) and having an attached arrange ^¬ te on its outer surface conductive ring structure (14) which are isolated from one another by the insulating structural member. 2. Insulator arrangement according to claim 1, characterized in that the ring structure (8) has an electrical conductivity Leitfä ^¬ , which is at least eight orders of magnitude higher than the conductivity of the adjacent surface of the structural element. 3. Insulator arrangement according to claim 1 or 2, characterized in that the ring structure (8) has an axial extension (10) which is at least half Di ^¬ bridge and at most four times the thickness of the structural element (4) in the radial direction. 4. insulator arrangement according to one of claims 1 to 3, character- ized in that the outer and the inner Ring structure (16) are mounted in the manner to each other that they with respect to a solder (18) on the longitudinal axis (20) of the structural element (4) aufwei ^¬ sen cover. 5. Insulator arrangement according to claim 1 or 4, characterized in that at least two structural elements (4, 4 ^λ ) are provided, which are joined together along their end faces, wherein each of the at least two structural elements (4, 4 ^λ ) at least one ring structure (8, 16). Insulator arrangement according to one of claims 1 to 5, characterized in that the structural element (4, 4 ^λ ) has an axial extent which is between 10 mm and 200 mm, preferably between 20 mm and 80 mm, be ^¬ particularly preferably between 20 mm and 40 mm. Insulator arrangement according to one of the preceding claims, characterized in that the distance of the ring ^¬ structures (8, 16) in the axial direction between 5 mm and 40 mm. Insulator arrangement according to one of the preceding claims, characterized in that a further coating of the structural element is provided on its inner side and / or on its outer side, which has a surface resistance of between 10 ⁸ ohms 10 ¹² ohms, preferably between 10 ohms 10 ohms lies. Insulator arrangement according to one of the preceding claims, characterized in that the ring structure (8, 16) in the form of a metallic structure, in particular in the form of a ring or in the form of a band is configured. Insulator arrangement according to one of claims 1 to 6, characterized in that the ring structure (8, 16) is applied in the form of a conductive coating. A vacuum interrupter for high or medium voltage applications, comprising an insulator assembly according to any one of claims 1 to 8.