CA2164481A1 - High voltage installation - Google Patents
High voltage installationInfo
- Publication number
- CA2164481A1 CA2164481A1 CA 2164481 CA2164481A CA2164481A1 CA 2164481 A1 CA2164481 A1 CA 2164481A1 CA 2164481 CA2164481 CA 2164481 CA 2164481 A CA2164481 A CA 2164481A CA 2164481 A1 CA2164481 A1 CA 2164481A1
- Authority
- CA
- Canada
- Prior art keywords
- protective coating
- installation
- voltage
- voltage installation
- electrically insulating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
- H01B3/10—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances metallic oxides
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G5/00—Installations of bus-bars
- H02G5/06—Totally-enclosed installations, e.g. in metal casings
- H02G5/066—Devices for maintaining distance between conductor and enclosure
- H02G5/068—Devices for maintaining distance between conductor and enclosure being part of the junction between two enclosures
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Gas-Insulated Switchgears (AREA)
- Insulators (AREA)
- Installation Of Bus-Bars (AREA)
Abstract
This high-voltage installation has a metallic housing (1, 5) which is filled with insulating gas and surrounds voltage-carrying active parts (3, 7). It is provided with insulators for the electrically insulating support of the active parts (3, 7) in the housing (1, 5), with drive means formed in an electrically insulating manner for the actuation of the mobile sections of the active parts and with at least one protective coating (11) which covers at least the insulators and the drive means formed in an electrically insulating manner.
It is intended to provide a high-voltage installation having a protective layer which is impermeable to liberated chemically aggressive decomposition products, in particular hydrofluoric acid, during the entire service life of the installation. This is achieved by the protective coating (11) being formed in such a way that decomposition products formed in the insulating gas during operation of the installation penetrate into the protective coating (11), and by the protective coating (11) having at least one component which reacts with the decomposition products to form at least one solid, nonhygroscopic reaction product. The reaction product produced by the reaction remains thereafter in the protective coating (11).
It is intended to provide a high-voltage installation having a protective layer which is impermeable to liberated chemically aggressive decomposition products, in particular hydrofluoric acid, during the entire service life of the installation. This is achieved by the protective coating (11) being formed in such a way that decomposition products formed in the insulating gas during operation of the installation penetrate into the protective coating (11), and by the protective coating (11) having at least one component which reacts with the decomposition products to form at least one solid, nonhygroscopic reaction product. The reaction product produced by the reaction remains thereafter in the protective coating (11).
Description
Se 23.12.1994 94/183 TITLE OF THE INVENTION
High-voltage installation BACKGROUND OF THE lNV~N'l'lON
Field of the Invention The invention proceeds from a high-voltage installation according to the preamble of claim-1.
Discussion of Backqround High-voltage installations which have a grounded, metallic enclosure which is filled with insulating gas, for example SF6, and whose internal surface situated opposite the high-voltage-carrying active parts is provided with a protective coating are known. Said protective coating is intended to render said surface smooth, inter alia so that it can be cleaned without fibers or other residues of cleaning aids being retained by surface roughness of the internal surface, as a result of which the dielectric strength of the gas-insulating gap would be reduced.
For the same reasons, the surface of the active parts is also frequently provided with a similar protective coating in such installations.
The publication DE 41 20 309 A1 discloses a high-voltage installation having a metallic enclosure which is filled with insulating gas and surrounds the voltage-carrying active parts. Provided on the internal surface of the enclosure, and also on the external surface of the active parts, is a partly multilayered protective coating. In this high-voltage installation, a reduction in the dielectric strength of the insulating-gas gaps as a result of freely mobile or fixed particles can occur only to a limited extent.
However, these protective coatings are, as a rule, unsuitable for converting chemically active switching residues or aggressive decomposition products into nonhygroscopic substances.
High-voltage installation BACKGROUND OF THE lNV~N'l'lON
Field of the Invention The invention proceeds from a high-voltage installation according to the preamble of claim-1.
Discussion of Backqround High-voltage installations which have a grounded, metallic enclosure which is filled with insulating gas, for example SF6, and whose internal surface situated opposite the high-voltage-carrying active parts is provided with a protective coating are known. Said protective coating is intended to render said surface smooth, inter alia so that it can be cleaned without fibers or other residues of cleaning aids being retained by surface roughness of the internal surface, as a result of which the dielectric strength of the gas-insulating gap would be reduced.
For the same reasons, the surface of the active parts is also frequently provided with a similar protective coating in such installations.
The publication DE 41 20 309 A1 discloses a high-voltage installation having a metallic enclosure which is filled with insulating gas and surrounds the voltage-carrying active parts. Provided on the internal surface of the enclosure, and also on the external surface of the active parts, is a partly multilayered protective coating. In this high-voltage installation, a reduction in the dielectric strength of the insulating-gas gaps as a result of freely mobile or fixed particles can occur only to a limited extent.
However, these protective coatings are, as a rule, unsuitable for converting chemically active switching residues or aggressive decomposition products into nonhygroscopic substances.
2 1 644~ 1 In modern high-voltage installations of the type described above, insulating parts composed of quartz-powder-filled or glass-fiber-reinforced casting resin are used only to a limited extent since the decomposition products of the insulating gas filling the high-voltage installation attack the silicates of the filling or reinforcement. If sulfur hexafluoride (SF6) is used as the insulating gas, as is now mostly the case, in particular the hydrofluoric acid (HF) which is then produced acts in a particularly aggressive manner on the silicates. If such an insulating part is coated with one of the conventional protective lacquers, said protective coating can only somewhat delay the penetration of the aggressive decomposition products. As experiments showed, conventional protective layers 100 ~m to 200 ~m thick had an inadequate protective action of only one to three hours' duration at room temperature. If a longer-lasting protection of the insulating part is to be achieved, the protective-lacquer layer has to be applied more thickly, which necessitates an expensive application of a plurality of lacquer layers each having intervening drying processes. A lasting protection against said aggressive decomposition products cannot, however, be achieved in this way.
SUMMARY OF THE INVENTION
Accordingly, as it is defined in the independent claims, one object of the invention is to provide a novel high-voltage installation having a protective layer which is impermeable to liberated, chemically aggressive decomposition products, in particular hydrofluoric acid, during the service life of the installation.
The advantages achieved by the invention are essentially to be seen in the fact that solid-state insulators having silicate-cont~;ning fillers can now be provided with a protective layer which prevents, with great reliability, the aggressive decomposition products, in particular the hydrofluoric acid, from being able to attack the silicate-containing fillers and thus being able to weaken the insulator mechanically and dielectrically. It is a substantial economic advantage if said solid-state insulators, which can be produced comparatively inexpensively, can now also be used in an aggressive environment with the aid of a protective layer which is simple to apply.
It is furthermore advantageous that, on the one hand, the aggressive decomposition products are rendered harmless and that, consequently, the number of freely mobile particles in the insulation gaps is reduced at the same time.
The aggressive decomposition products penetrating into the protective layer are reliably converted into nonhygroscopic, electrically insulating substances which are bound in the protective layer.
The high-voltage installation is provided with a metallic housing which is filled with insulating gas and surrounds voltage-carrying active parts. In addition, it is provided with insulators for the electrically insulating support of the active parts in the housing and with drive means formed in an electrically insulating manner for the actuation of the mobile sections of the active parts. The insulators and the drive means formed in an electrically insulating manner are coated with a protective coating.
The protective coating is formed in such a way that decomposition products formed in the insulating gas during the operation of the installation penetrate into the protective coating, and it has at least one component which reacts with the decomposition products to form at least one solid, nonhygroscopic and electrically insulating reaction product.
The at least one component is given the form of a nanostructured material. Al203 or MgO are provided as the nanostructured material. An epoxy lacquer or a lacquer based on polyester, on acrylic resin or on polyurethane is provided as the base for the protective coating. However, it is also possible to use a resin which is provided with a polyester (PETP) fiber reinforcement as the base for the protective coating.
This type of protective coating is particularly advantageous, since it then can be used, for example, as the base for the filament winding of an insulating tube.
The component to be added in the form of a pigment makes the surface of the protective coating matt, thus advantageously improving at the same time the adherence of further layers of the protective coating which may additionally be applied.
Further refinements of the invention are the subject of the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention, its development and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, which represent merely one embodiment and wherein:
Fig. 1 shows a first partial section through a high-voltage installation according to the invention, Fig. 2 shows a second partial section through a high-voltage installation according to the invention, and Fig. 3 shows a partial section through an insulating tube, for example an explosion chamber insulating tube.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views and all elements not necessary for a direct understanding of the invention are omitted, in Fig. 1 a first, greatly simplified partial section through a high-voltage installation according to the invention is shown. A substantially cylindrically constructed metallic housing 1 of a pressure-tight design encloses an interior space 2 which is filled with pressurized insulating gas, for example SF6. Arranged in the center of the housing 1 are voltage-carrying active parts 3, shown in a very simplified form. The housing 1 is connected in a pressure-tight manner by means of a flange connection 4 to a further, substantially cylindrically constructed metallic housing 5 of a pressure-tight design. This housing 5 also encloses a further interior space 6 which is filled with pressurized insulating gas, for example SF6. Arranged in the center of the housing 5 are voltage-carrying active parts 7, shown in a very simplified form. The two interior spaces 2 and 6 are separated from each other here by a partitioning insulator 8 which is of a disk-shaped design and is let into the flange connection 4 in a pressure-tight manner. The partitioning insulator 8 has a disk-shaped insulator body 9, into which a cast-in fitting 10 is cast in a pressure-tight manner. The cast-in fitting 10 is connected electrically conductively to the active parts 3 and 7. The partitioning insulator 8 supports the active parts 3 and 7 against the housings l and 5.
The interior spaces 2 and 6 are subjected to decomposition products which are formed, for example, by arcs generated in power switches or other switchgear (not shown).
The insulator body 9 has been produced here from quartz-powder-filled and/or glass-fiber-reinforced casting resin. The surfaces of the insulator body 9 are provided with in each case a protective coating 9, which may be of a single-layered or multilayered composition. In the figure, the protective coating 11 is shown comparatively thick, for the sake of better viewing clarity; as a rule, the individual layers of these protective coatings 11 have thicknesses of a few ~m to about 100 ~m. Greater thicknesses of the protective coatings 11 are achieved by repeated application of the corresponding layer, if appropriate with intervening drying processes. The surfaces of the active parts 3 and 7 are coated entirely or partially with one of the conventional protective layers 12. The internal surfaces of the housings 1 and 5 are coated entirely or partially with one of the conventional protective layers 13. However, it is also possible, instead of these protective layers 12 or 13, to apply entirely or partially protective coatings having a material composition corresponding to that of the protective coating 11. Furthermore, it is conceivable to coat the protective coatings 12 or 13 entirely or partially with a further protective coating whose material composition corresponds to that of the protective coating 11.
In Fig. 2, a second, greatly simplified partial section through a high-voltage installation according to the invention is shown. The substantially cylindrically constructed metallic housing 1 of a pressure-tight design encloses the interior space 2 which is filled with pressurized insulating gas, for example SF6. Here too, voltage-carrying active parts, shown in a very simplified form, are arranged in the center of the housing 1. Shown here as an active part, for example, is a disconnector 14. The disconnector 14 has a movable contact 15, which slides in a guiding part 16, and a fixed mating contact 17, which is set up for receiving the movable contact 15. Both the guiding part 16 and the fixed mating contact 17 are positioned in the housing 1 by insulators (not shown), which are designed as partitioning insulators or as supporting insulators provided with openings. The movable contact 15 is moved out of an insulating material in the axial direction by a drive rod 18 connected displaceably to it. The drive rod 18 is actuated by means of a drive shaft 19 mounted in a rotatable and pressure-tight manner in the housing 1. The drive driving the drive shaft 19 is not shown. The drive rod 18 may also have other forms.
The electrically insulating drive rod 18 has been produced here from quartz-powder-filled or glass-2 1 644~ 1 fiber-reinforced casting resin. The surfaces of the drive rod 18 are provided completely with a protective coating 11, which may be of a single-layered or multilayered composition. In the figure, the protective coating 11 is shown comparatively thick, for the sake of better viewing clarity; as a rule, the individual layers of these protective coatings 11 have thicknesses of about 50 ~m to a few 100 ~m. Greater thicknesses of the protective coatings 11 are achieved by repeated application of the corresponding layer, if appropriate with intervening drying processes.
Various types of power switches which are used in gas-insulated switching installations have explosion chambers with pressure-resistant, electrically insulating explosion chamber tubes. These explosion chamber tubes may also be produced from quartz-powder-filled and/or glass-fiber-reinforced casting resin if they are coated with the protective coating 11. In Fig. 3, a partial section through such a cylindrically designed explosion chamber tube 20 is shown, which tube has a center axis 23. The explosion chamber tube 20 has in addition a wall 21, the outside of which is coated with a protective coating 11 if this tube is used in a metal-enclosed gas-insulated switching installation. If the tube is used in an SF6 switch which is intended for outdoor installation, this outer protective coating 11 is not necessary. In the case of the explosion chamber tube 20, the internal surface is provided with a further protective coating 22, which either has the same composition as the mentioned protective coating 11 or which, for example in the case of explosion chamber tubes 20 wound on a winding mandrel, is formed as a polyester-fiber-reinforced resin layer, a chemically reactive component comprising at least one very finely dispersed pigment being admixed with the resin before processing. These pigment particles are distributed homogeneously in the resin. However, a PETP-fiber nonwoven together with an epoxy resin with which corresponding pigment particles have been admixed may also be used. In the production of such explosion chamber tubes 20, as a rule first of all the fiber reinforcement is applied in the form of a nonwoven to the winding mandrel, this nonwoven is then impregnated with the polyester resin. The pigment particles distributed homogeneously in the polyester resin have such small dimensions that they cannot be arrested by the nonwoven, i.e. the pigment particles are also distributed homogeneously in the finished protective coating 22. Thereafter, the wall 21 is wound onto this protective coating 22 in a known way, and after the curing of this wound composite part the protective coating 11 is applied on the outside.
The base for the protective coating 11 is formed in each case by a lacquer which has a comparatively high surface resistance and consequently a good creep resistance; furthermore, it must be chemically resistant to aggressive decomposition products and be thermally resistant. In addition, the lacquer must not be hygroscopic. An acrylic lacquer or a lacquer based on polyester or based on polyurethane or based on epoxy resin is frequently used, but other types of lacquer are also conceivable, depending on the intended application. The chemically reactive component in the form of very finely dispersed pigments is admixed with the lacquer before processing. As a rule, 3 to 30 percent by weight of this component are admixed.
Depending on the area of use of the protective coating 11, various, correspondingly prepared substances may be used as the very finely dispersed pigments, such as for example carbides, nitrides and metal oxides such as ZnO, Fe203, Bi2o3, PdO, AgO, TeO, CuO~ Sb23~ Ti2~ ZrO2, Al203, In2O3, SnO, V20s and MgO. For use in metal-enclosed gas-insulated switching installations which are filled with SF6 gas, A1203 and/or MgO can be used particularly advantageously.
The A1203, or the MgO, is prepared with the aid of one of the known processes such that particles in the nanosize range are produced; these particles have a size of about 5 nm to 50 nm. A particle size of 25 nm has been found to be particularly favorable with regard to the behavior of the particles in the chemical S reaction. With this particle size, the pigment fraction in the lacquer achieves an effective surface area of an optimum size without however over-thickening the lacquer, which would hinder its processing.
1st exemplary embodiment:
Nano-Al2O3 type C of the Degussa company, Frankfurt, FRG, is used as the very finely dispersed pigment. An acrylic resin, to be mixed from two components A and B, of the Dold company, CH-8304 Wallisellen, Switzerland, is provided as the lacquer.
parts by weight of the lacquer component A, designated by IB-16/A, product number F 5190, are used.
The lacquer component A is mixed with 3 to 30 percent by weight, based on the finished lacquer, of nano-Al2O3 type C to form a mixture. The mixture is advantageously storable in a closed container, since the pigment is of such a fine form that it cannot settle in this mixture. 1 part by weight of the lacquer component B of the acrylic lacquer, designated by IB-16/B, product number F 5191, is admixed with the mixture. The resulting lacquer ready for processing may be diluted, if need be, with xylene, with ethyl acetate or with general purpose thinner.
The admixture of 30 percent by weight of nano-Al2O3 results in a protective coating 11 with a matt surface. This matt surface is to be regarded as having good grip and particularly well suited for permiting a further layer of the protective coating 11 to adhere particularly well. The thickness of the individual layers is dependent on the consistency of the lacquer;
in the dry state, a thickness in the range from 40 ~m to about 80 ~m is aimed for. As the top layer, as a rule the protective coating 11 receives a pigment-free varnish, permiting particularly good cleaning of the coating.
2 ~ 6448 1 In the case of this exemplary embodiment, the particle size of the admixed nano-Al2O3 type C was 20 nm. Protective coatings 11 produced with this lacquer and of a total thickness of about 200 ym have kept decomposition products of the SF6 gas away from the insulator body 9 protected therewith for more than ten hours. Fatigue tests accordingly show clearly better results than the tests with customary lacquers.
These fatigue tests have not yet been concluded at present.
The effectiveness of the chemically reactive component contained in the lacquer and in the form of a very finely dispersed pigment is evident from the following reaction equation:
Al2O3 + 6HF ~ 2AlF3 + 3H2O
The hydrofluoric acid HF is converted into the solid, nonhygroscopic compound AlF3, rem~; n; ng in the protective coating, and into water. The water leaves the lacquer coating and is rendered harmless by the active filter in connection with the respective interior space of the metal-enclosed gas-insulated high-voltage switching installation. The compound AlF3 is electrically insulating; the insulation strength of the partitioning insulator 8 is not adversely affected by this compound remaining in the protective coating 11 .
2nd exemplary embodiment:
An approximately 60 mm wide strip of polyester (PETP) nonwoven is wound with half overlap around a winding mandrel. After completion of the winding, this arrangement is impregnated with a mixture of cycloaliphatic epoxy resin with nanostructured MgO. Of the nanostructured MgO, 3 to 30 percent by weight were admixed. The curing of the resin to form the protective coating 22 took place under reduced pressure. Then, a glass-fiber-reinforced plastics tube tGRP) was wound onto this protective coating 22 in the conventional filament-winding process. After curing of this blank, a plastics tube which has on the inside a ~ 94/183 protective coating 22 with a reinforcement of a polyester (PETP) nonwoven is obtained. If this plastics tube is intended for installation in a metal-enclosed gas-insulated switching installation, its outside is also provided with a protective coating 11 .
The effectiveness of this very finely dispersed pigment contained in the lacquer is evident from the following reaction equation:
MgO + 2HF ~ MgF2 + H2O
The hydrofluoric acid HF is converted into the solid, nonhygroscopic compound MgF2, remaining in the protective coating 22 or 11, and into water. The water leaves the lacquer coating and is rendered harmless by the active filter in connection with the respective interior space of the metal-enclosed gas-insulated high-voltage switching installation. The compound MgF2 is electrically insulating; the insulation strength of the explosion chamber tube 20 is not adversely affected by this compound rP~; n; ng in the protective coating 22 or 11.
In contrast to the use of very finely dispersed Al2O3, the use of very finely dispersed MgO offers the additional advantage that the penetration time of the gaseous hydrofluoric acid (HF) is extended by more than double. Further fatigue tests are also envisaged with protective coatings 22 of such a form.
It may, however, also be advisable not only to provide the insulators with the protective coating 11, but additionally to provide the protective coating 11 in a region or in several regions of the high-voltage installation, to be precise in particular wherever switching gases or other switching residues can occur in a particularly concentrated form.
The electrically insulating parts produced from quartz-powder-filled and/or glass-fiber-reinforced casting resin have a particularly high mechanical strength; now, thanks to the protective coating 11, 22, this advantageous material can also be used in gas-insulated switching installations, in particular also in SF6-filled high-voltage installations, which brings with it considerable commercial advantages.
Furthermore, it is conceivable also to coat with a protective coating 11 outdoor insulators produced from quartz-powder-filled and/or glass-fiber-reinforced casting resin, in order to protect these insulators better against environmental effects in this way. It is also possible, with the aid of chemically suitable components, to adapt the protective coating 11 to particularly critical environmental effects, in order to extend their service life advantageously in this way.
In the metal-enclosed gas-insulated switching installations, the aggressive decomposition products occur as a rule only during a limited time after the respective switching operations, since in these installations there are provided active filters which continuously clean and dehumidify the insulating gas.
The protective coatings 11 and 22 are therefore subjected to the aggressive decomposition products in each case only during this limited time. In addition to this is the fact that the decomposition products, which although diffused into the protective coating 11, 22 have not yet been chemically converted, diffuse out of the protective coatings 11, 22 again when the concentration of the aggressive decomposition products in the insulating gas of the high-voltage installation has reduced. The chemical effectiveness of the nano-pigments incorporated in the protective coatings 11, 22is accordingly preserved over a comparatively long period of time. If the application thickness of the protective coatings 11, 22 is increased, and possibly also the number of successively applied coatings, the duration of effect of the coatings can be further extended. In the metal-enclosed gas-insulated switching installations, it is always ensured that the contamination time, during which the aggressive decomposition products act on the protective coatings 11, 22, accumulated during the entire service life of the installation is significantly less than the effective time of these coatings. The protective coatings 11, 12 accordingly need not be renewed before the end of the normal service life of the installation.
The metal-enclosed gas-insulated switching installations, which are designed for above-averagely frequent switching actions, are provided with correspondingly adapted protective coatings 11, 22, so that insulating parts of silicate-cont~;n;ng materials can be used without any problems in these high-voltage installations as well.
In contrast to the use of very finely dispersed Al2O3, the use of very finely dispersed MgO offers the additional advantage that the penetration time of the gaseous hydrofluoric acid tHF) is extended by more than double.
If pigments with a coarser structure than the described nanostructure are used, the chemical effectiveness is somewhat impaired; however, applications where such a coarser structure can be used advantageously are quite conceivable. Furthermore, it is also possible to use pigments which have a coarser structure, mixed with nanostructured material, in order to achieve in this way a specific adaptation to particular given operational requirements.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
LIST OF DESIGNATIONS
1 Housing 2 Interior space 5 3 Active parts 4 Flange connection Housing 6 Interior space 7 Active parts 10 8 Partitioning insulator 9 Insulator body Cast-in fitting 11 Protective coating 12, 13 Protective layer 15 14 Disconnector Movable contact 16 Guiding part 17 Mating contact 18 Drive rod 20 19 Drive shaft Explosion chamber tube 21 Wall 22 Protective coating 23 Center axis
SUMMARY OF THE INVENTION
Accordingly, as it is defined in the independent claims, one object of the invention is to provide a novel high-voltage installation having a protective layer which is impermeable to liberated, chemically aggressive decomposition products, in particular hydrofluoric acid, during the service life of the installation.
The advantages achieved by the invention are essentially to be seen in the fact that solid-state insulators having silicate-cont~;ning fillers can now be provided with a protective layer which prevents, with great reliability, the aggressive decomposition products, in particular the hydrofluoric acid, from being able to attack the silicate-containing fillers and thus being able to weaken the insulator mechanically and dielectrically. It is a substantial economic advantage if said solid-state insulators, which can be produced comparatively inexpensively, can now also be used in an aggressive environment with the aid of a protective layer which is simple to apply.
It is furthermore advantageous that, on the one hand, the aggressive decomposition products are rendered harmless and that, consequently, the number of freely mobile particles in the insulation gaps is reduced at the same time.
The aggressive decomposition products penetrating into the protective layer are reliably converted into nonhygroscopic, electrically insulating substances which are bound in the protective layer.
The high-voltage installation is provided with a metallic housing which is filled with insulating gas and surrounds voltage-carrying active parts. In addition, it is provided with insulators for the electrically insulating support of the active parts in the housing and with drive means formed in an electrically insulating manner for the actuation of the mobile sections of the active parts. The insulators and the drive means formed in an electrically insulating manner are coated with a protective coating.
The protective coating is formed in such a way that decomposition products formed in the insulating gas during the operation of the installation penetrate into the protective coating, and it has at least one component which reacts with the decomposition products to form at least one solid, nonhygroscopic and electrically insulating reaction product.
The at least one component is given the form of a nanostructured material. Al203 or MgO are provided as the nanostructured material. An epoxy lacquer or a lacquer based on polyester, on acrylic resin or on polyurethane is provided as the base for the protective coating. However, it is also possible to use a resin which is provided with a polyester (PETP) fiber reinforcement as the base for the protective coating.
This type of protective coating is particularly advantageous, since it then can be used, for example, as the base for the filament winding of an insulating tube.
The component to be added in the form of a pigment makes the surface of the protective coating matt, thus advantageously improving at the same time the adherence of further layers of the protective coating which may additionally be applied.
Further refinements of the invention are the subject of the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention, its development and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, which represent merely one embodiment and wherein:
Fig. 1 shows a first partial section through a high-voltage installation according to the invention, Fig. 2 shows a second partial section through a high-voltage installation according to the invention, and Fig. 3 shows a partial section through an insulating tube, for example an explosion chamber insulating tube.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views and all elements not necessary for a direct understanding of the invention are omitted, in Fig. 1 a first, greatly simplified partial section through a high-voltage installation according to the invention is shown. A substantially cylindrically constructed metallic housing 1 of a pressure-tight design encloses an interior space 2 which is filled with pressurized insulating gas, for example SF6. Arranged in the center of the housing 1 are voltage-carrying active parts 3, shown in a very simplified form. The housing 1 is connected in a pressure-tight manner by means of a flange connection 4 to a further, substantially cylindrically constructed metallic housing 5 of a pressure-tight design. This housing 5 also encloses a further interior space 6 which is filled with pressurized insulating gas, for example SF6. Arranged in the center of the housing 5 are voltage-carrying active parts 7, shown in a very simplified form. The two interior spaces 2 and 6 are separated from each other here by a partitioning insulator 8 which is of a disk-shaped design and is let into the flange connection 4 in a pressure-tight manner. The partitioning insulator 8 has a disk-shaped insulator body 9, into which a cast-in fitting 10 is cast in a pressure-tight manner. The cast-in fitting 10 is connected electrically conductively to the active parts 3 and 7. The partitioning insulator 8 supports the active parts 3 and 7 against the housings l and 5.
The interior spaces 2 and 6 are subjected to decomposition products which are formed, for example, by arcs generated in power switches or other switchgear (not shown).
The insulator body 9 has been produced here from quartz-powder-filled and/or glass-fiber-reinforced casting resin. The surfaces of the insulator body 9 are provided with in each case a protective coating 9, which may be of a single-layered or multilayered composition. In the figure, the protective coating 11 is shown comparatively thick, for the sake of better viewing clarity; as a rule, the individual layers of these protective coatings 11 have thicknesses of a few ~m to about 100 ~m. Greater thicknesses of the protective coatings 11 are achieved by repeated application of the corresponding layer, if appropriate with intervening drying processes. The surfaces of the active parts 3 and 7 are coated entirely or partially with one of the conventional protective layers 12. The internal surfaces of the housings 1 and 5 are coated entirely or partially with one of the conventional protective layers 13. However, it is also possible, instead of these protective layers 12 or 13, to apply entirely or partially protective coatings having a material composition corresponding to that of the protective coating 11. Furthermore, it is conceivable to coat the protective coatings 12 or 13 entirely or partially with a further protective coating whose material composition corresponds to that of the protective coating 11.
In Fig. 2, a second, greatly simplified partial section through a high-voltage installation according to the invention is shown. The substantially cylindrically constructed metallic housing 1 of a pressure-tight design encloses the interior space 2 which is filled with pressurized insulating gas, for example SF6. Here too, voltage-carrying active parts, shown in a very simplified form, are arranged in the center of the housing 1. Shown here as an active part, for example, is a disconnector 14. The disconnector 14 has a movable contact 15, which slides in a guiding part 16, and a fixed mating contact 17, which is set up for receiving the movable contact 15. Both the guiding part 16 and the fixed mating contact 17 are positioned in the housing 1 by insulators (not shown), which are designed as partitioning insulators or as supporting insulators provided with openings. The movable contact 15 is moved out of an insulating material in the axial direction by a drive rod 18 connected displaceably to it. The drive rod 18 is actuated by means of a drive shaft 19 mounted in a rotatable and pressure-tight manner in the housing 1. The drive driving the drive shaft 19 is not shown. The drive rod 18 may also have other forms.
The electrically insulating drive rod 18 has been produced here from quartz-powder-filled or glass-2 1 644~ 1 fiber-reinforced casting resin. The surfaces of the drive rod 18 are provided completely with a protective coating 11, which may be of a single-layered or multilayered composition. In the figure, the protective coating 11 is shown comparatively thick, for the sake of better viewing clarity; as a rule, the individual layers of these protective coatings 11 have thicknesses of about 50 ~m to a few 100 ~m. Greater thicknesses of the protective coatings 11 are achieved by repeated application of the corresponding layer, if appropriate with intervening drying processes.
Various types of power switches which are used in gas-insulated switching installations have explosion chambers with pressure-resistant, electrically insulating explosion chamber tubes. These explosion chamber tubes may also be produced from quartz-powder-filled and/or glass-fiber-reinforced casting resin if they are coated with the protective coating 11. In Fig. 3, a partial section through such a cylindrically designed explosion chamber tube 20 is shown, which tube has a center axis 23. The explosion chamber tube 20 has in addition a wall 21, the outside of which is coated with a protective coating 11 if this tube is used in a metal-enclosed gas-insulated switching installation. If the tube is used in an SF6 switch which is intended for outdoor installation, this outer protective coating 11 is not necessary. In the case of the explosion chamber tube 20, the internal surface is provided with a further protective coating 22, which either has the same composition as the mentioned protective coating 11 or which, for example in the case of explosion chamber tubes 20 wound on a winding mandrel, is formed as a polyester-fiber-reinforced resin layer, a chemically reactive component comprising at least one very finely dispersed pigment being admixed with the resin before processing. These pigment particles are distributed homogeneously in the resin. However, a PETP-fiber nonwoven together with an epoxy resin with which corresponding pigment particles have been admixed may also be used. In the production of such explosion chamber tubes 20, as a rule first of all the fiber reinforcement is applied in the form of a nonwoven to the winding mandrel, this nonwoven is then impregnated with the polyester resin. The pigment particles distributed homogeneously in the polyester resin have such small dimensions that they cannot be arrested by the nonwoven, i.e. the pigment particles are also distributed homogeneously in the finished protective coating 22. Thereafter, the wall 21 is wound onto this protective coating 22 in a known way, and after the curing of this wound composite part the protective coating 11 is applied on the outside.
The base for the protective coating 11 is formed in each case by a lacquer which has a comparatively high surface resistance and consequently a good creep resistance; furthermore, it must be chemically resistant to aggressive decomposition products and be thermally resistant. In addition, the lacquer must not be hygroscopic. An acrylic lacquer or a lacquer based on polyester or based on polyurethane or based on epoxy resin is frequently used, but other types of lacquer are also conceivable, depending on the intended application. The chemically reactive component in the form of very finely dispersed pigments is admixed with the lacquer before processing. As a rule, 3 to 30 percent by weight of this component are admixed.
Depending on the area of use of the protective coating 11, various, correspondingly prepared substances may be used as the very finely dispersed pigments, such as for example carbides, nitrides and metal oxides such as ZnO, Fe203, Bi2o3, PdO, AgO, TeO, CuO~ Sb23~ Ti2~ ZrO2, Al203, In2O3, SnO, V20s and MgO. For use in metal-enclosed gas-insulated switching installations which are filled with SF6 gas, A1203 and/or MgO can be used particularly advantageously.
The A1203, or the MgO, is prepared with the aid of one of the known processes such that particles in the nanosize range are produced; these particles have a size of about 5 nm to 50 nm. A particle size of 25 nm has been found to be particularly favorable with regard to the behavior of the particles in the chemical S reaction. With this particle size, the pigment fraction in the lacquer achieves an effective surface area of an optimum size without however over-thickening the lacquer, which would hinder its processing.
1st exemplary embodiment:
Nano-Al2O3 type C of the Degussa company, Frankfurt, FRG, is used as the very finely dispersed pigment. An acrylic resin, to be mixed from two components A and B, of the Dold company, CH-8304 Wallisellen, Switzerland, is provided as the lacquer.
parts by weight of the lacquer component A, designated by IB-16/A, product number F 5190, are used.
The lacquer component A is mixed with 3 to 30 percent by weight, based on the finished lacquer, of nano-Al2O3 type C to form a mixture. The mixture is advantageously storable in a closed container, since the pigment is of such a fine form that it cannot settle in this mixture. 1 part by weight of the lacquer component B of the acrylic lacquer, designated by IB-16/B, product number F 5191, is admixed with the mixture. The resulting lacquer ready for processing may be diluted, if need be, with xylene, with ethyl acetate or with general purpose thinner.
The admixture of 30 percent by weight of nano-Al2O3 results in a protective coating 11 with a matt surface. This matt surface is to be regarded as having good grip and particularly well suited for permiting a further layer of the protective coating 11 to adhere particularly well. The thickness of the individual layers is dependent on the consistency of the lacquer;
in the dry state, a thickness in the range from 40 ~m to about 80 ~m is aimed for. As the top layer, as a rule the protective coating 11 receives a pigment-free varnish, permiting particularly good cleaning of the coating.
2 ~ 6448 1 In the case of this exemplary embodiment, the particle size of the admixed nano-Al2O3 type C was 20 nm. Protective coatings 11 produced with this lacquer and of a total thickness of about 200 ym have kept decomposition products of the SF6 gas away from the insulator body 9 protected therewith for more than ten hours. Fatigue tests accordingly show clearly better results than the tests with customary lacquers.
These fatigue tests have not yet been concluded at present.
The effectiveness of the chemically reactive component contained in the lacquer and in the form of a very finely dispersed pigment is evident from the following reaction equation:
Al2O3 + 6HF ~ 2AlF3 + 3H2O
The hydrofluoric acid HF is converted into the solid, nonhygroscopic compound AlF3, rem~; n; ng in the protective coating, and into water. The water leaves the lacquer coating and is rendered harmless by the active filter in connection with the respective interior space of the metal-enclosed gas-insulated high-voltage switching installation. The compound AlF3 is electrically insulating; the insulation strength of the partitioning insulator 8 is not adversely affected by this compound remaining in the protective coating 11 .
2nd exemplary embodiment:
An approximately 60 mm wide strip of polyester (PETP) nonwoven is wound with half overlap around a winding mandrel. After completion of the winding, this arrangement is impregnated with a mixture of cycloaliphatic epoxy resin with nanostructured MgO. Of the nanostructured MgO, 3 to 30 percent by weight were admixed. The curing of the resin to form the protective coating 22 took place under reduced pressure. Then, a glass-fiber-reinforced plastics tube tGRP) was wound onto this protective coating 22 in the conventional filament-winding process. After curing of this blank, a plastics tube which has on the inside a ~ 94/183 protective coating 22 with a reinforcement of a polyester (PETP) nonwoven is obtained. If this plastics tube is intended for installation in a metal-enclosed gas-insulated switching installation, its outside is also provided with a protective coating 11 .
The effectiveness of this very finely dispersed pigment contained in the lacquer is evident from the following reaction equation:
MgO + 2HF ~ MgF2 + H2O
The hydrofluoric acid HF is converted into the solid, nonhygroscopic compound MgF2, remaining in the protective coating 22 or 11, and into water. The water leaves the lacquer coating and is rendered harmless by the active filter in connection with the respective interior space of the metal-enclosed gas-insulated high-voltage switching installation. The compound MgF2 is electrically insulating; the insulation strength of the explosion chamber tube 20 is not adversely affected by this compound rP~; n; ng in the protective coating 22 or 11.
In contrast to the use of very finely dispersed Al2O3, the use of very finely dispersed MgO offers the additional advantage that the penetration time of the gaseous hydrofluoric acid (HF) is extended by more than double. Further fatigue tests are also envisaged with protective coatings 22 of such a form.
It may, however, also be advisable not only to provide the insulators with the protective coating 11, but additionally to provide the protective coating 11 in a region or in several regions of the high-voltage installation, to be precise in particular wherever switching gases or other switching residues can occur in a particularly concentrated form.
The electrically insulating parts produced from quartz-powder-filled and/or glass-fiber-reinforced casting resin have a particularly high mechanical strength; now, thanks to the protective coating 11, 22, this advantageous material can also be used in gas-insulated switching installations, in particular also in SF6-filled high-voltage installations, which brings with it considerable commercial advantages.
Furthermore, it is conceivable also to coat with a protective coating 11 outdoor insulators produced from quartz-powder-filled and/or glass-fiber-reinforced casting resin, in order to protect these insulators better against environmental effects in this way. It is also possible, with the aid of chemically suitable components, to adapt the protective coating 11 to particularly critical environmental effects, in order to extend their service life advantageously in this way.
In the metal-enclosed gas-insulated switching installations, the aggressive decomposition products occur as a rule only during a limited time after the respective switching operations, since in these installations there are provided active filters which continuously clean and dehumidify the insulating gas.
The protective coatings 11 and 22 are therefore subjected to the aggressive decomposition products in each case only during this limited time. In addition to this is the fact that the decomposition products, which although diffused into the protective coating 11, 22 have not yet been chemically converted, diffuse out of the protective coatings 11, 22 again when the concentration of the aggressive decomposition products in the insulating gas of the high-voltage installation has reduced. The chemical effectiveness of the nano-pigments incorporated in the protective coatings 11, 22is accordingly preserved over a comparatively long period of time. If the application thickness of the protective coatings 11, 22 is increased, and possibly also the number of successively applied coatings, the duration of effect of the coatings can be further extended. In the metal-enclosed gas-insulated switching installations, it is always ensured that the contamination time, during which the aggressive decomposition products act on the protective coatings 11, 22, accumulated during the entire service life of the installation is significantly less than the effective time of these coatings. The protective coatings 11, 12 accordingly need not be renewed before the end of the normal service life of the installation.
The metal-enclosed gas-insulated switching installations, which are designed for above-averagely frequent switching actions, are provided with correspondingly adapted protective coatings 11, 22, so that insulating parts of silicate-cont~;n;ng materials can be used without any problems in these high-voltage installations as well.
In contrast to the use of very finely dispersed Al2O3, the use of very finely dispersed MgO offers the additional advantage that the penetration time of the gaseous hydrofluoric acid tHF) is extended by more than double.
If pigments with a coarser structure than the described nanostructure are used, the chemical effectiveness is somewhat impaired; however, applications where such a coarser structure can be used advantageously are quite conceivable. Furthermore, it is also possible to use pigments which have a coarser structure, mixed with nanostructured material, in order to achieve in this way a specific adaptation to particular given operational requirements.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
LIST OF DESIGNATIONS
1 Housing 2 Interior space 5 3 Active parts 4 Flange connection Housing 6 Interior space 7 Active parts 10 8 Partitioning insulator 9 Insulator body Cast-in fitting 11 Protective coating 12, 13 Protective layer 15 14 Disconnector Movable contact 16 Guiding part 17 Mating contact 18 Drive rod 20 19 Drive shaft Explosion chamber tube 21 Wall 22 Protective coating 23 Center axis
Claims (9)
1. A high-voltage installation having a metallic housing (1, 5) which is filled with insulating gas and surrounds voltage-carrying active parts (3, 7, 14), having insulators for the electrically insulating support of the active parts (3, 7, 14) in the housing (1, 5), having drive means formed in an electrically insulating manner for the actuation of the mobile sections of the active parts, having at least one protective coating (11, 22) which covers at least the insulators and the drive means formed in an electrically insulating manner and is formed in such a way that decomposition products formed in the insulating gas during operation of the installation penetrate into it, the protective coating (11, 22) having at least one component which is composed of a nanostructured material and reacts with the penetrating decomposition products to form at least one solid, nonhygroscopic reaction product, wherein - MgO is provided as the nanostructured material.
2. The high-voltage installation as claimed in claim 1, wherein - Al2O3 in nanostructured form is admixed with the nanostructured material.
3. The high-voltage installation as claimed in claim 2, wherein - the nanostructured material has a particle size of from 10 nm to 50 nm, preferably however a particle size of 25 nm.
4. The high-voltage installation as claimed in claim 1, wherein - an epoxy lacquer or a lacquer based on polyester, on acrylic resin or on polyurethane is provided as the base for the protective coating (11, 22).
5. The high-voltage installation as claimed in claim 1, wherein - a resin which is provided with a fiber reinforcement, in particular of polyester (PETP), is provided as the base for the protective coating (22).
6. The high-voltage installation as claimed in claim 5, wherein - the protective coating (22) is used as the base for the filament winding of an insulating tube.
7. The high-voltage installation as claimed in one of claims 1 to 6, wherein - the insulators and/or the drive means formed in an electrically insulating manner are produced from quartz-powder-filled or glass-fiber-reinforced casting resin.
8. The high-voltage installation as claimed in claim 1, wherein - the at least one component is formed as a mixture of at least one nanostructured material with at least one coarser structured material, the at least two materials being either of the same or of different chemical compositions.
9. The high-voltage installation as claimed in claim 1, wherein - 3 to 30 percent by weight of the at least one component are incorporated in the respective protective coating (11, 22).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19944446944 DE4446944A1 (en) | 1994-12-28 | 1994-12-28 | High voltage system |
| DEP4446944.6 | 1994-12-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2164481A1 true CA2164481A1 (en) | 1996-06-29 |
Family
ID=6537345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2164481 Abandoned CA2164481A1 (en) | 1994-12-28 | 1995-12-05 | High voltage installation |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0724317A3 (en) |
| JP (1) | JPH08237827A (en) |
| BR (1) | BR9506094A (en) |
| CA (1) | CA2164481A1 (en) |
| DE (1) | DE4446944A1 (en) |
| NO (1) | NO955156L (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE29620438U1 (en) * | 1996-11-13 | 1997-01-23 | Siemens AG, 80333 München | Enclosure housing for gas-insulated, metal-enclosed switchgear |
| KR100899311B1 (en) * | 1998-12-10 | 2009-05-27 | 미쓰비시 마테리알 가부시키가이샤 | Fpd protecting film, method of producing the same and fpd using the same |
| DE10020263B4 (en) * | 2000-04-25 | 2010-04-08 | Siemens Ag | Insulating components for SF6-insulated switches and switchgear |
| JP4564466B2 (en) * | 2006-03-31 | 2010-10-20 | 株式会社東芝 | Gas insulation equipment |
| JP4939989B2 (en) * | 2007-03-26 | 2012-05-30 | 株式会社東芝 | Cast insulation |
| JP5044345B2 (en) * | 2007-09-21 | 2012-10-10 | 株式会社東芝 | Switchgear |
| JP5127607B2 (en) * | 2008-07-08 | 2013-01-23 | 株式会社東芝 | Gas insulation equipment |
| CN104051084A (en) * | 2013-03-15 | 2014-09-17 | 西门子公司 | Disassemble insulator for gas insulated switchgear |
| CN105449606A (en) * | 2015-12-22 | 2016-03-30 | 广东宝士电气有限公司 | Portable waterproof and fireproof busbar groove |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH466391A (en) * | 1965-08-26 | 1968-12-15 | Bbc Brown Boveri & Cie | Electrical equipment, in particular encapsulated switchgear, switches, transformers or converters, and methods for their production |
| CH596658A5 (en) * | 1975-11-12 | 1978-03-15 | Sprecher & Schuh Ag | |
| US4102851A (en) * | 1977-03-22 | 1978-07-25 | Westinghouse Electric Corp. | Alumina-thickened cycloaliphatic epoxy materials for use in atmospheres of arced sulfur hexafluoride and articles thereof |
| JPS54164271A (en) * | 1978-06-16 | 1979-12-27 | Mitsubishi Electric Corp | Supporting insulator for gas insulating equipment |
| CH658339A5 (en) * | 1983-03-21 | 1986-10-31 | Sprecher & Schuh Ag | Mechanically stressed, electrically insulating component for high-voltage switchgear containing SF6, and process for manufacturing it |
| JP2563101B2 (en) * | 1987-01-26 | 1996-12-11 | 松下電工 株式会社 | Epoxy resin composition for heavy electric parts |
| JPS63192895A (en) * | 1987-02-05 | 1988-08-10 | Sumitomo Electric Ind Ltd | Coating member |
| JPH0664958B2 (en) * | 1988-06-20 | 1994-08-22 | 富士電機株式会社 | Polyester premix parts for high voltage equipment |
| JPH0725993B2 (en) * | 1988-10-03 | 1995-03-22 | 日立化成工業株式会社 | Epoxy resin composition |
| JP2830301B2 (en) * | 1990-02-15 | 1998-12-02 | 株式会社明電舎 | Alumina-filled resin cured product |
| DE4120309A1 (en) * | 1991-06-20 | 1992-12-24 | Asea Brown Boveri | HIGH VOLTAGE SYSTEM |
| JP2910953B2 (en) * | 1992-01-16 | 1999-06-23 | アルプス電気株式会社 | Manufacturing method of magnetic head |
| JPH05242733A (en) * | 1992-02-25 | 1993-09-21 | Hitachi Cable Ltd | Electrically insulating material |
| JPH05266763A (en) * | 1992-03-19 | 1993-10-15 | Toshiba Corp | Circuit breaker insulated by sulfur hexafluoride gas |
-
1994
- 1994-12-28 DE DE19944446944 patent/DE4446944A1/en not_active Withdrawn
-
1995
- 1995-12-05 CA CA 2164481 patent/CA2164481A1/en not_active Abandoned
- 1995-12-11 EP EP95810780A patent/EP0724317A3/en not_active Withdrawn
- 1995-12-19 NO NO955156A patent/NO955156L/en unknown
- 1995-12-27 BR BR9506094A patent/BR9506094A/en not_active Application Discontinuation
- 1995-12-27 JP JP7341362A patent/JPH08237827A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| NO955156L (en) | 1996-07-01 |
| JPH08237827A (en) | 1996-09-13 |
| DE4446944A1 (en) | 1996-07-04 |
| BR9506094A (en) | 1997-12-23 |
| EP0724317A2 (en) | 1996-07-31 |
| NO955156D0 (en) | 1995-12-19 |
| EP0724317A3 (en) | 1996-12-27 |
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