COATED CONDUCTOR IN A HIGH-VOLTAGE DEVICE AND METHOD FOR INCREASING THE DIELECTRIC STRENGTH

Abstract

A high-voltage device has an encapsulation housing and at least one bushing for at least one electrical conductor leading into the encapsulation housing and/or leading out of the encapsulation housing. The at least one electrical conductor is coated with an insulation layer. The insulation layer increases the dielectric strength in the high-voltage device, in particular in the region of the bushing.

Claims

1-14. (canceled)

15. A high-voltage device, comprising: an encapsulation housing; at least one bushing for guiding at least one electrical conductor into said encapsulation housing and/or out of said encapsulation housing; and an insulation layer coated on said at least one electrical conductor.

16. The high-voltage device according to claim 15, wherein said at least one electrical conductor is completely coated with said insulating layer along an entire length of said conductor.

17. The high-voltage device according to claim 15, wherein said at least one electrical conductor is coated with said insulating layer exclusively in a region of said bushing.

18. The high-voltage device according to claim 17, wherein said at least one electrical conductor is coated with said insulating layer exclusively at an opening in said encapsulation housing.

19. The high-voltage device according to claim 15, wherein the insulating layer has a relative permittivity of approximately 1 or the relative permittivity of said insulating layer is greater than 1.

20. The high-voltage device according to claim 15, wherein said insulating layer is formed of a plurality of layers.

21. The high-voltage device according to claim 20, wherein said plurality of layers have a decreasing permittivity from layer to layer.

22. The high-voltage device according to claim 21, wherein a layer that is in direct contact with said electrical conductor has a highest permittivity.

23. The high-voltage device according to claim 15, wherein said insulating layer consists of at least one polymer material selected from the group consisting of silicone, Teflon®, polytetrafluoroethylene (PTFE), and polychlorotrifluoroethylene (PCTFE); or said insulating layer comprises at least one polymer selected from the group consisting of silicone, Teflon®, PTFE, and/or PCTFE.

24. The high-voltage device according to claim 15, wherein said insulating layer has a layer thickness in a range of millimeters or in a range of centimeters.

25. The high-voltage device according to claim 15, wherein a thickness of said insulating layer and a dielectric permittivity of said insulating layer are selected such that a field strength at a surface of said electrical conductor equals a field strength at an outer surface of said insulating layer.

26. The high-voltage device according to claim 15, wherein said encapsulation housing includes a flange and an insulator fastened in a mechanically stable manner on said flange.

27. The high-voltage device according to claim 26, wherein said insulator is at least one of a hollow-tubular or circular-cylindrical insulator made of at least one material selected from the group consisting of silicone, ceramic, and composite material and having ribs formed on an outer circumference thereof, and wherein a center axis of said insulator is coaxial with a longitudinal axis of said at least one electrical conductor.

28. The high-voltage device according to claim 15, wherein at least one electrode at ground potential is enclosed by said bushing.

29. The high-voltage device according to claim 15, which comprises at least one switching unit of a high-voltage circuit breaker arranged in said encapsulation housing and/or connected via said at least one electrical conductor to power consumers, power generators, and/or lines of a power grid.

30. The high-voltage device according to claim 15, wherein said at least one electrical conductor consists of a metal or a metallic alloy and has a shape of a bar and/or a rod.

31. The high-voltage device according to claim 15, wherein said metal is selected from the group consisting of copper, aluminum, and steel, and said bar is circular-cylindrical.

32. The high-voltage device according to claim 15, wherein said encapsulation housing and/or said bushing are filled with clean air.

33. A method of increasing a dielectric strength in a high-voltage device, the method which comprises coating at least one electrical conductor with an insulating layer in a region of a bushing through which the at least one electrical conductor leads into, or out of, an encapsulation housing of the high-voltage device.

34. The method according to claim 33, which comprises forming a high-voltage device having an encapsulation housing, at least one bushing for guiding at least one electrical conductor into said encapsulation housing and/or out of said encapsulation housing, and an insulation layer coated on said at least one electrical conductor.

Description

[0029] In the FIGS.

[0030] FIG. 1 schematically shows an electrical conductor 4 coated using an insulating layer 5, and

[0031] FIG. 2 schematically shows a sectional view of a detail of a high-voltage device 1 according to the invention, having an opening in an encapsulation housing 2, and having a bushing 3 for a live conductor 4 through the opening, wherein the electrical conductor 4 is coated using an insulating layer 5.

[0032] An electrical conductor 4 is shown in FIG. 1, which is used in a high-voltage device according to the invention as a live conductor for electrically connecting power consumers, power generators, and/or power lines in a power grid. The electrical conductor 4 is formed in the form of a circular-cylindrical rod or a circular-cylindrical tube, having a lateral surface which is partially coated using an insulating layer 5. The electrical conductor 4 is, for example, made of and/or comprises copper, aluminum, and/or steel. The diameter is, for example, in the range of 1 to 10 cm and the length is, for example, in the range of 1 to 10 m.

[0033] The insulating layer 5 is made of and/or comprises, for example, silicone, Teflon, PTFE, and/or PCTFE. The layer thickness is, for example, in the range of several millimeters up to centimeters, in particular 1 cm. In the exemplary embodiment of FIG. 1, the electrical conductor 4 is only partially coated using the insulating layer 5, for example only on half of its length. The coating thickness and the coating length are dependent here, for example, on the shape and size of the bushing, the maximum amperages and/or voltages of the high-voltage device, the material selection of the conductor 4 and the material selection of the insulating layer 5, and/or the shape, thickness, and length of the conductor 4. The material selection, thickness, and length of the coating of the conductor 4 using an electrically insulating material are optimized in particular in such a way that the field distribution along the conductor 4 is standardized in the area, for example, of a bushing of a high-voltage device according to the invention.

[0034] FIG. 2 schematically shows a sectional view of a detail from a high-voltage device 1 according to the invention, having an opening in an encapsulation housing 2 of the high-voltage device 1. The opening comprises a flange 9, which is in the form of a ring or rim. Boreholes for fastening means, for example screws, are formed in the flange 9. A hollow-tubular insulator 10 is arranged standing perpendicularly on the flange 9, and is fastened via the fastening means, in particular screws, in a mechanically stable manner on the flange 9. The encapsulation housing 2 having flange 9 is formed, for example, from a metal, in particular aluminum. The insulator 10 is, for example, made of ceramic, silicone, and/or composite materials. In particular rim-shaped ribs for extending leakage current paths are formed on the outer circumference of the insulator 10.

[0035] The hollow-tubular insulator 10, having circular cross section, has a longitudinal axis 6 which stands perpendicularly on the opening plane of the circular opening, and intersects or penetrates the opening in the encapsulation housing 2 in the circle center point. A switching unit of a high-voltage circuit breaker, comprised by the high-voltage device 1 according to the invention, is arranged, for example, in the encapsulation housing 2 and electrically connected via conductor 4 to power consumers, power generators, and/or power lines of a power grid outside the encapsulation housing 2. An electrical conductor 4 which is a live conductor 4 in operation of the high-voltage device 1 or in the closed state of the switching unit is, as shown in detail in FIG. 1, in particular in the form of a rod or bar, having a longitudinal axis implied by or identical with the longitudinal axis 6 of the insulator.

[0036] When current flows through the electrical conductor 4, there is an electrical and magnetic field around the conductor 4. The conductor 4 is at high voltage potential, in particular up to 1200 kV, and the encapsulation housing 2 is grounded, i.e., at ground potential. The potential difference between grounded encapsulation housing 2 and live conductor 4 can result in voltage flashovers and/or short-circuits. To prevent this, the opening in the encapsulation housing 2 has a sufficient radius, which ensures a minimum distance between conductor 4 and encapsulation housing 4, which is sufficiently large to prevent voltage flashovers. The required minimum distance is dependent on the insulating gas, using which the encapsulation housing 4 and the insulator 10 are filled, for example clean air, and on the pressure of the insulating gas, for example 1 bar. Further measures can enable reductions of the minimum distance.

[0037] One possibility for reducing the minimum distance, with sufficient dielectric strength in the area of the opening in the encapsulation housing 4, is the use of an electrode 7 at ground potential, as shown in FIG. 2. The electrode 7 is made of a metal, in particular aluminum, copper, and/or steel, is in the form of a hollow cylinder or hollow tube, having circular cross section. The hollow-tubular electrode 7, having circular cross section, has a longitudinal or center axis 6 which stands perpendicularly on the opening plane of the circular opening and intersects or penetrates the opening in the encapsulation housing 2 in the circle center point. The longitudinal or center axis of the electrode 7 at ground potential is implied by or identical with the longitudinal axis 6 of the insulator 10. The electrode 7 is fastened in a mechanically stable and electrically conductive manner using fastening means, for example screws, on the flange 9 of the encapsulation housing 2 and protrudes into the insulator 10 or into its cavity in the interior. The electrode 7 changes the electrical field between encapsulation housing 2 and live conductor 4 in such a way that voltage elevations at the opening of the encapsulation housing 2 or the flange 9 are shielded by the electrode 7 or are displaced into the interior of the insulator 10.

[0038] According to the invention, further shielding of the electrical field or changing of the field between encapsulation housing 2 and electrical or live conductor 4 is possible by using an insulating layer 5 on the electrical conductor 4. The insulating layer 5 changes the electrical field along the electrical conductor 4 in such a way that it is made uniform and is displaced further into the interior of the insulator 10 and into the encapsulation housing 2. The probability of free strong electrons for initiating an electrical discharge between electrical conductor 4 and encapsulation housing 2 is inhibited. Local field elevations due to a surface roughness on the surface of the electrical conductor 4 are reduced or prevented. Voltage flashovers and/or short-circuits between the encapsulation housing 2 and the live conductor 4 are thus prevented, even with reduced size of the opening in the encapsulation housing 2 or the flange 9, low insulating gas pressures, upon use of alternative insulating gases, such as clean air, and/or elevated voltage levels in operation of the high-voltage device 1.

[0039] Material savings and lower costs for materials with smaller sizes and wall thicknesses of encapsulation housings 2 and insulators 10 are linked thereto, lower weight with increased dielectric strength in the area of the bushing 3 of the live conductor 4 through the opening in the encapsulation housing 2, and the use of alternative switching gases is possible, such as clean air, at low pressures, for example 1 bar. The reliability and service life of the high-voltage device 1 are increased and maintenance expenditure is reduced.

[0040] The above-described exemplary embodiments can be combined with one another and/or can be combined with the prior art. Thus, for example, high-voltage devices 1 can comprise high-voltage circuit breakers, isolators, transformers, arrestors, measurement transducers, and/or bushings. High-voltage devices 1, in particular circuit breakers, are, for example, designed as gas-insulated circuit breakers, i.e., gas-insulated switch gears. The basic principle, having an insulating layer on a conductor in a bushing of the conductor through openings at ground potential, is also usable in open air circuit breakers or open air high-voltage devices. The invention is usable in dead tank facilities, i.e., with a switching unit arranged in a grounded housing. However, the basic principles are also usable in live tank facilities, i.e., with a switching unit at high voltage potential arranged in an insulator. The electrical conductor 4 is made, for example, circular cylindrical. Further shapes, for example having elliptical cross section and/or formed as a truncated cone, are also possible.

[0041] The encapsulation housing 2 of the high-voltage device 1 is, for example, in the form of a vessel, and is closed gas-tight via the insulators 10. Vessels are, for example, spherical or cylindrical, further shapes are also possible. Connections between elements of the high-voltage device are carried out, for example, in a mechanically stable manner via fastening means, in particular screws, and at least one flange. Further or alternative connection technologies, in particular adhesive bonds, welded bonds, and/or soldered bonds, are also applicable. The use of seals for the gas-tight connection of elements, in particular copper seals, is possible. Electrode ends, in particular of the electrode 7 at ground potential, are rounded, for example, to avoid field elevations. Further shapes of the electrode ends, for example extending linearly, angled, rounded having different rounding radii, are possible.

[0042] The insulating layer 5 on the electrical conductor 4 is formed, for example, as a layer or as a layer stack made up of multiple layers. The layers can have differing permittivity, in particular decreasing permittivity from layer to layer, for example with the highest permittivity of the layer directly in connection with the at least one electrical conductor 4. Due to the application of further insulating layers having different relative permittivity, wherein, for example, the permittivity of the inner layer is highest and each further layer is formed having a lower or having decreasing permittivity, but always having a permittivity greater than the permittivity of gas, i.e., greater than 1, more pronounced equalization of the electrical field can be achieved in comparison to only one layer, to thus further relieve the critical areas dielectrically.

LIST OF REFERENCE NUMERALS

[0043] 1 high-voltage device [0044] 2 encapsulation housing [0045] 3 bushing [0046] 4 live conductor [0047] 5 insulating layer [0048] 6 longitudinal or center axis [0049] 7 electrode at ground potential [0050] 8 contact means [0051] 9 flange [0052] 10 insulator