High voltage apparatus and method for increasing dielectric strength in high voltage apparatus - Patents.com

Abstract

The present invention relates to a high-voltage device (1) having an encapsulated housing (2) and at least one bushing (3) for at least one live conductor (4) leading into and / or leading out of the encapsulated housing (2), which encloses at least one electrode (5) at free potential, which increases the dielectric strength of the high-voltage device (1), particularly in the region of the bushing (3).

Description

[Technical field]

[0001] The present invention relates to a high voltage apparatus and a method for increasing the dielectric strength in a high voltage apparatus, the high voltage apparatus comprising an encapsulated housing and at least one bushing for at least one live conductor leading into and / or leading out of the encapsulated housing.

[0002] High-voltage equipment is designed for voltages in the range of several tens to several hundreds of kilovolts, in particular for voltages of 1200 kV, and currents in the range of several hundreds of kiloamperes. High-voltage equipment includes, for example, high-voltage switchgear, disconnectors, transformers, surge arresters, instrument transformers and / or bushings. High-voltage equipment, in particular switchgear, is designed, for example, as outdoor-type switchgear and / or as gas-insulated switchgear, i.e. as insulator-type, in which the switching unit is arranged in an insulator at high voltage potential, or as tank-type, in which the switching unit is arranged in a grounded housing.

[0003] The tank-type gas-insulated switchgear comprises an encapsulated housing, especially designed in the form of a cylindrical tank, made of, for example, aluminum, and a number of bushings for live conductors, for connecting a switching unit arranged inside the encapsulated housing to power consumers, generators and / or power lines in a power system. The encapsulated housing, especially in the form of a tank, is designed gas-tight and has, for example, two openings, especially designed in the form of circular flanges, into which an insulator housing, especially of a hollow cylindrical shape, is fixed gas-tight. In the insulator housing or insulator, the live conductors run from the external connection terminals at the hermetically sealed housing ends to the openings of the encapsulated housing and through them, for example, to the switching unit, in order to electrically connect the switching unit to power consumers, generators and / or power lines in a power system.

[0004] The encapsulated housing of the high-voltage equipment, in particular of the switchgear, is arranged on a support, in particular fixed in a mechanically stable manner to a concrete foundation, for example on a steel mast. The encapsulated housing is electrically grounded in order to minimize the risk to maintenance workers and / or bystanders. A particularly long hollow cylindrical insulator is arranged or fixed on the side of the encapsulated housing opposite the support, for example perpendicular or at an angle to the encapsulated housing, in particular pointing upwards from the encapsulated housing. Thus, a sufficient electrical insulation distance of the connection terminals from the ground potential and / or from the foundation is obtained and electrical flashovers can be prevented. The inside of the encapsulated housing and the insulator are filled with insulating and / or insulating gas, in particular SF6.

[0005] This insulating gas insulates the interior of the high-voltage installation, for example the switchgear and the live conductors, from the earthed encapsulating housing. In the region of the bushing, in particular in the region of the transition from the circular opening designed in the form of a flange of the encapsulating housing to the fixed, in particular hollow cylindrical, insulator, sufficient dielectric strength can be ensured between the earthed encapsulating housing and the live conductors, in particular at high voltage potential. If the openings in the encapsulating housing are circular, the live conductors are arranged equidistantly with respect to the encapsulating housing, in particular so that they penetrate the circular plane of the opening perpendicularly in the center of the circle. Depending on the maximum voltage of the high-voltage installation and the insulating gas used as well as its pressure, these openings have a size or circumference that ensures sufficient dielectric strength, so that electrical flashover between the conductors and the encapsulating housing can be reliably prevented.

[0006] The electric field or electric field peak in the region of the opening is changed or reduced, i.e. shielded, starting from the live conductor by a number of grounded electrodes, in particular by a circular hollow cylindrical metal electrode arranged inside the insulator and mechanically fixed to the flange of the encapsulating housing. This allows the application of high voltages, in particular in the range of several hundred kilovolts, in this high-voltage installation without electrical flashovers and / or short circuits occurring between the electric conductor at high voltage potential or the live conductor in the bushing region and the grounded encapsulating housing. The high voltage levels of the high-voltage installation require large diameters of the openings in the encapsulating housing for long-term safe operation, which leads to high costs for insulators with large circumferences and the use of barrier gases with high dielectric strength, in particular SF6 and / or high pressures of the insulating gas, which leads to high costs for the insulators and large wall thicknesses of the encapsulating housing in order to ensure sufficient mechanical stability over time.

[0007] Barring gases such as SF6 are harmful to the climate. Alternative barrier gases such as clean air, i.e. scrubbed air, have a smaller dielectric strength. The use of a climate-friendly barrier gas such as clean air requires a larger opening diameter of the opening in the encapsulated housing and / or a higher pressure of the barrier gas, with the disadvantages mentioned above. Measures such as the use of multiple earthed control electrodes and / or the application of insulating paint to the conductors and / or to the openings in the encapsulated housing can only increase the dielectric strength to an insufficient extent for certain voltage levels. The use of the high voltage switchgear is therefore limited. Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a high-voltage device which overcomes the above-mentioned problems and a method for increasing the dielectric strength in a high-voltage device, in particular in which the dielectric strength in the bushing area of ​​the high-voltage device is high, in particular when using an alternative barrier gas such as clean air, allowing high voltage levels at advantageous costs and with material savings, in particular when using a barrier gas having a low gas pressure, for example in the range of ambient air, and / or when the bushing diameter is comparable to or smaller than the bushing diameter of a high-voltage device filled with SF6. [Means for solving the problem]

[0009] The above-mentioned problem is solved by a high-voltage arrangement having the features of claim 1 and / or by a method according to claim 13 for increasing the dielectric strength in a high-voltage arrangement, in particular in the above-mentioned high-voltage arrangement. Advantageous embodiments of the high-voltage arrangement according to the invention and / or of the method according to the invention for increasing the dielectric strength in a high-voltage arrangement, in particular in the above-mentioned high-voltage arrangement, are set out in the dependent claims. The subject matter of the two main claims can be combined with each other and with the features of the dependent claims, and the features of the dependent claims can be combined with each other.

[0010] The high-voltage device according to the invention comprises an encapsulating housing and at least one bushing for at least one live conductor or electric conductor. In the following, live conductor is used as a synonym for electric conductor in order to explain the effect of the invention, especially when a current flows through the conductor. The at least one conductor is led into and / or led out of the encapsulating housing. At least one electrode at free potential is surrounded by a bushing.

[0011] The at least one electrode at free potential allows the use of a bushing with a small diameter, especially when using a climate-friendly barrier gas such as clean air instead of a climate-harmful barrier gas such as SF6. A high-voltage device with at least one electrode at free potential allows the use of a bushing with a small diameter, especially when using a climate-friendly barrier gas such as clean air, which is cost-effective and saves material, and allows the use of a barrier gas with a low gas pressure, e.g. in the range of ambient air, with a high dielectric strength in the bushing area of ​​the high-voltage device at high voltage levels, which allows for encapsulated housings and insulators with a small wall thickness.

[0012] The high-voltage installation comprises at least one switching unit of a high-voltage switchgear, which is arranged in particular in an encapsulated housing and / or which can be connected to power consumers, generators and / or power lines in a power grid via at least one live conductor. The switching units of the high-voltage switchgear are installed in an encapsulated housing of the above-mentioned type with at least one bushing for at least one live conductor or electric conductor, which combines with the above-mentioned advantages as a high-voltage installation, in particular for the high-voltage switchgear.

[0013] At least one electrode at free potential can be cylindrical, in particular a cylindrical electrode of circular cross section, which is simple and cost-effective and can be arranged equidistantly around the live conductor or electrical conductor.

[0014] The central axis of the at least one electrode at free potential can be arranged to coincide or be aligned with the longitudinal axis of the at least one live conductor or electrical conductor, thereby providing optimal shielding of the electric field of the bushing, especially at the opening of the encapsulating housing.

[0015] The at least one electrode at ground potential can be surrounded, in particular spatially surrounded, by the bushing. The at least one electrode at ground potential can be arranged at a distance from the at least one electrode at free potential. The at least one electrode at ground potential can at least partially surround the at least one electrode at free potential. This results in further shielding of the electric field in the region of the opening of the encapsulated housing, in particular in good shielding of the opening against live conductors. The combination of an electrode at ground potential and an electrode at free potential results in a high dielectric strength in the bushing region and / or in the region of the opening of the encapsulated housing, which results in the above-mentioned advantages. This combination allows a further increase in the shielding effect in addition to the use of only one electrode or one type of electrode. By arranging the at least one electrode at ground potential around the at least one electrode at free potential, it is possible to arrange or fix the electrode at ground potential to the encapsulated housing or around the opening of the flange of the encapsulated housing in a grounded manner.

[0016] The central axis of the at least one electrode at free potential can be arranged to coincide or be identical to the central axis of the at least one electrode at ground potential. The at least one electrode at free potential can be made longer along its central axis than the at least one electrode at ground potential. This results in an optimal shielding of the opening of the encapsulation housing for the electric or live conductor, which is combined with the above-mentioned advantages.

[0017] The at least one electrode at free potential can be held at an equal distance to the at least one live conductor by an electrically insulating spacer, in particular a spacer made of ceramic, plastic, silicone, PTFE, Teflon, epoxy resin and / or composite material, which ensures that the at least one electrode at free potential is not grounded but at free potential, so that optimal shielding is obtained, in particular when it is arranged at an equal distance to the at least one live conductor. Materials such as ceramic, plastic, silicone, PTFE, Teflon, epoxy resin and / or composite materials have good electrical insulating properties, are cost-effective and mechanically stable, and can hold the at least one electrode at free potential at an equal distance to the at least one live conductor in a mechanically stable manner, especially over the long term, in the encapsulated housing.

[0018] The encapsulated housing can have a flange to which an insulator, in particular an insulator formed in the shape of a hollow pipe and / or cylinder and having in particular a number of ribs on its outer periphery, can be fixed in a mechanically stable manner. The flange allows a mechanically stable, long-term robust and in particular gas-tight fixation of the insulator to the encapsulated housing. In this way, a gas-tight housing of a high-voltage device with an encapsulated housing and an insulator is possible, which has conductors that are at least partially electrically shielded in the housing. In particular, the insulator and / or these electrodes arranged in the encapsulated housing are protected, for example, from the effects of weather.

[0019] The central axis of the insulator can be aligned or coaxial with the central axis of at least one electrode at free potential and / or with the longitudinal axis of at least one live conductor, which allows for a space-saving and cost-effective electrode arrangement with good shielding effect.

[0020] The at least one electrode at free potential can protrude into the encapsulation housing and / or into the insulator. By leading the electrode at free potential through an opening into the encapsulation housing and into the insulator, a high shielding effect of the opening in the encapsulation housing is obtained by the electrode at free potential, leading to the above-mentioned advantages.

[0021] At least one electrode at free potential can be made of and / or consist of a metal, in particular copper, aluminum and / or steel and / or a metal alloy, which produces a good electric shielding effect and can be easily manufactured or processed into any shape at advantageous costs.

[0022] The high-voltage device, in particular the encapsulated housing and / or the bushing, can be filled with clean air, which is environmentally friendly at advantageous costs and is particularly climate-neutral. The lower dielectric strength of clean air compared to conventional insulating gases such as SF6 can be compensated for by using at least one electrode at free potential, in particular in the region of the opening of the encapsulated housing through which the live conductor or electrical conductor passes. This allows the use of the same encapsulated housing for different insulating gases, which allows for a simple replacement in existing high-voltage devices when an electrode at free potential is provided, which has a climate-friendly effect, and further allows cost-effective mass production in new installations, especially when using climate-friendly insulating gases. Encapsulated housings and insulators with small dimensions can be used, which, together with the above-mentioned advantages, saves material and costs.

[0023] The method according to the invention for increasing the dielectric strength in a high-voltage apparatus, in particular in the high-voltage apparatus described above, comprises increasing the dielectric strength of at least one electrode at free potential surrounded by at least one bushing for at least one live conductor led into and / or led out of the encapsulation housing of the high-voltage apparatus compared to a bushing without an electrode at free potential.

[0024] The advantages of the method according to the invention as defined in claim 13 for increasing the dielectric strength in high-voltage installations, in particular in the above-mentioned high-voltage installations, are similar to the above-mentioned advantages of the high-voltage installation according to the invention as defined in claim 1 and vice versa.

[0025] In the following, an embodiment of the invention is illustrated diagrammatically in the drawings and explained in more detail. [Brief description of the drawings]

[0026] [Figure 1] It is a schematic diagram of a cross section of a part of a high-voltage device 1 according to the invention, in which an opening is formed in an encapsulated housing 2 through which a bushing 3 for a live conductor 4 passes and an electrode 5 at free potential is surrounded by the bushing 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] FIG. 1 shows a schematic cross-section of a part of a high-voltage device 1 according to the invention, in which an encapsulated housing 2 of the high-voltage device 1 has an opening. The opening is provided with a flange 9 formed in the shape of a ring or a flange. The flange 9 is provided with a number of holes for fastening means, for example screws. A hollow pipe-shaped insulator 10 is arranged perpendicular to the flange 9 and is mechanically stably fixed to the flange 9 by fastening means, in particular screws. The encapsulated housing 2 with the flange 9 is formed, for example, of a metal, in particular aluminum. The insulator 9 is made, for example, of ceramic, silicone and / or composite material. A number of ribs, in particular flange-shaped, are formed on the outer periphery of the insulator 10 in order to lengthen the creepage current path.

[0028] The hollow pipe-like insulator 10 with a circular cross section has a longitudinal axis 6 perpendicular to the opening plane of the circular opening, which intersects or passes through the opening of the capsule housing 2 in the center of the circle. In the capsule housing 2, for example a switching unit of the high-voltage switchgear included in the high-voltage device 1 according to the invention is arranged and is electrically connected via a conductor 4 to power consumers, generators and / or power lines in the power system outside the capsule housing 2. The electric conductor 4 which is a live conductor 4 during operation of the high-voltage device 1 or in the closed state of the switching unit, which will be generally called live conductor 4 in the following for all switching positions or states of the high-voltage device in order to clearly indicate the action on the openings and electrodes, is in particular formed in the form of a rod or bar and has a longitudinal axis which coincides or is identical with the longitudinal axis 6 of the insulator. The live conductor 4 consists for example of copper, aluminum and / or conductive steel.

[0029] When a current flows through the live conductor 4, electric and magnetic fields are generated around the conductor 4. The conductor 4 is at a high voltage potential, in particular up to 1200 kV, and the encapsulation housing 2 is earthed, i.e. at earth potential. A potential difference between the earthed encapsulation housing 2 and the live conductor 4 can cause a voltage flashover and / or a short circuit. To prevent this, the opening of the encapsulation housing 2 has a radius sufficient to ensure a minimum distance between the conductor 4 and the encapsulation housing 4, which radius is large enough to prevent a voltage flashover. This required minimum distance depends on the insulating gas, e.g. clean air, filled in the encapsulation housing 4 and the insulator 10, and further on the pressure of the insulating gas, e.g. 1 bar (10 5 By further measures, such as the application of an insulating paint to the conductor 4 and / or to the inside of the encapsulation housing 2, it is possible to reduce this minimum distance.

[0030] One possibility for shortening the minimum distance while having sufficient dielectric strength in the region of the opening of the encapsulated housing 4 is to use an electrode 7 at ground potential, as shown in the figure. This electrode 7 is made of metal, in particular aluminum, copper and / or steel, and is in the shape of a hollow cylinder or hollow pipe with a circular cross section. The hollow pipe electrode 7 with a circular cross section has a longitudinal or central axis 6 which is perpendicular to the opening plane of the circular opening and intersects or passes through the opening of the encapsulated housing 2 at the center of the circle. The longitudinal or central axis of the electrode 7 applied to ground potential includes or is identical with the longitudinal axis 6 of the insulator 10. The electrode 7 is mechanically stable and conductively fixed to the flange 9 of the encapsulated housing 2, for example by means of a fixing means such as a screw, and projects into the insulator 10 or into the hollow space therein. This electrode 7 changes the electric field between the encapsulation housing 2 and the live conductor 4 so that a voltage rise at the opening or flange 9 of the encapsulation housing 2 is either shielded by the electrode 7 or transferred to the inside of the insulator 10.

[0031] According to the invention, further shielding or modification of the electric field between the encapsulation housing 2 and the live conductor 4 is possible by using an electrode 5 at free potential. This electrode 5 is made of metal, in particular aluminum, copper and / or steel, and is formed as a hollow cylinder or pipe with a circular cross section, which is smaller than the cross section of the electrode 7. The hollow pipe electrode 5 with a circular cross section has a longitudinal or central axis 6 which is perpendicular to the opening plane of the circular opening and which intersects with or passes through the opening of the encapsulation housing 2 in the center of the circle. The longitudinal or central axis of the electrode 5 at free potential is identical to the longitudinal axis 6 of the insulator 10 and to the central axis of the electrode 7 at ground potential.

[0032] The electrode 5 is fixed to the flange 9 of the encapsulation housing 2 via a spacer 8 in a mechanically stable and electrically insulating manner, and protrudes into the insulator 10 and into the encapsulation housing 2. The electrode 5 further protrudes into the insulator 10 as an electrode 7, and shields the electrode 7 at ground potential from the live conductor 4. The spacer 8 is made of an electrically insulating material, in particular ceramic, plastic, silicone, PTFE, Teflon, epoxy resin and / or composite material. The spacer fixes the electrode 5 at free potential to the live conductor 4 and to the encapsulation housing 2, i.e., to the flange 9, in a particularly equidistant manner.

[0033] The electrode 5 at free potential changes the electric field between the encapsulation housing 2 and the live conductor 4 such that the voltage rise at the encapsulation housing 2 or opening, as well as the voltage rise at the electrode 7 at ground potential, are shielded or reduced by the electrode 5 at free potential and transferred further inside the insulator 10 and into the encapsulation housing 2. This prevents voltage flashover and / or short circuit between the encapsulation housing 2 and the live conductor 4 even when the opening or flange 9 of the encapsulation housing 2 is smaller in size, when the insulating gas pressure is low, when an alternative insulating gas such as clean air is used, and / or when voltage levels rise during operation of high voltage equipment.

[0034] This results in material savings and lower costs in the case of smaller dimensions and wall thicknesses of the encapsulated housing 2 and the insulator 10, lighter weight with increased dielectric strength in the region of the bushing 3 of the live conductor 4 passing through the opening in the encapsulated housing 2, and allows the use of alternative barrier gases such as clean air at lower pressures, e.g. 1 bar. The reliability and service life of the high voltage device 1 are improved and maintenance costs are reduced.

[0035] The above-mentioned embodiments can be combined with one another and / or with the prior art. Thus, for example, the high-voltage installation 1 can include a high-voltage switchgear, a disconnector, a transformer, a lightning arrester, an instrument transformer and / or a bushing. The high-voltage installation 1, in particular the switchgear, is designed for example as a gas-insulated switchgear, i.e. as a gas-insulated switchgear. The basic principle of providing an electrode at free potential in a bushing of a conductor passing through an opening at ground potential is also applicable in outdoor switchgear or outdoor high-voltage installation. The invention can be used in tank-type installations, i.e. in installations with switching units arranged in a grounded housing. But it can also be used in principle in insulator-type installations, i.e. in installations with switching units at high-voltage potential arranged in an insulator. This electrode 5 at free potential is formed, for example, cylindrically. Furthermore, other shapes are also possible, for example with an elliptical cross section and / or formed as a truncated cone.

[0036] The capsule-type housing 2 of the high-voltage device is, for example, tank-shaped and hermetically closed by an insulator 10. The tank-shaped container is, for example, spherical or cylindrical, other shapes are also possible. The connection between the elements of the high-voltage device is made in a mechanically stable manner, for example via fastening means, in particular screws and at least one flange. Other or alternative connection techniques, in particular adhesive, welded and / or brazed connections, are likewise applicable. The use of seals, in particular copper seals, for the hermetic connection of several elements is possible. The spacer is, for example, disk-shaped and made in one piece. Alternatively, spacers made of several pieces with the same or different part shapes are also possible. The ends of the electrodes are, for example, rounded to avoid electric field buildup. Other shapes of the electrode ends are also possible, for example linear, curved, rounded with several rounding radii, etc. [Explanation of symbols]

[0037] 1 High voltage equipment 2. Capsule-type housing 3 Bushing 4 Live conductors 5. Electrodes at free potential 6 Longitudinal or central axis 7 Electrode at ground potential 8 Spacer 9 Flange 10 Insulators

Claims

1. A high-voltage device (1) having an encapsulated housing (2) and at least one bushing (3) for at least one live conductor (4) leading into and / or leading out of the encapsulated housing (2), At least one electrode (5) at free potential is surrounded by said bushing (3), said at least one electrode (5) at free potential is cylindrically shaped; A high voltage device (1).

2. 2. The high-voltage device (1) according to claim 1, characterized in that at least one switching unit is included and arranged in the encapsulated housing (2) and / or is connected to power consumers, generators and / or power lines of a power grid via the at least one live conductor (4).

3. 3. The high-voltage device (1) according to claim 1 or 2, characterized in that the central axis (6) of the at least one electrode (5) at free potential is arranged to coincide with the longitudinal axis of the at least one live conductor (4).

4. 4. The high-voltage device (1) according to claim 1, characterized in that at least one electrode (7) at ground potential is surrounded by the bushing (3), and this at least one electrode (7) at ground potential is spaced apart from the at least one electrode (5) at free potential and / or the at least one electrode (5) at free potential is at least partially spatially surrounded.

5. 5. The high-voltage device (1) according to claim 4, characterized in that the central axis of the at least one electrode (5) at free potential is arranged to coincide with the central axis of the at least one electrode (7) at ground potential and / or the at least one electrode (5) at free potential is formed longer along its central axis than the at least one electrode (7) at ground potential.

6. 6. The high-voltage device (1) according to claim 1, characterized in that the at least one electrode (5) at free potential is held in the encapsulated housing (2) by an electrically insulating spacer (8) in a particularly equidistant manner relative to the at least one live conductor (4).

7. The capsule-type housing (2) has one flange (9) and one insulator (10), The insulator (10) is formed in a hollow pipe shape and / or a cylindrical shape, has a plurality of ribs on its outer periphery, and is fixed to the flange (9) in a mechanically stable manner. High-voltage device (1) according to any one of the preceding claims.

8. 8. The high-voltage device (1) according to claim 7, characterized in that the central axis of the insulator (10) is arranged to coincide with the central axis (6) of the at least one electrode (5) at free potential and / or with the longitudinal axis of the at least one live conductor (4).

9. 9. High-voltage device (1) according to claim 7 or 8, characterized in that the at least one electrode (5) at free potential protrudes into the encapsulated housing (2) and / or into the insulator (10).

10. High-voltage device (1) according to any one of the preceding claims, characterized in that the at least one electrode (5) at free potential is made of a metal and / or a metal alloy.

11. 11. High-voltage device (1) according to any one of claims 1 to 10, characterized in that the high-voltage device (1), the encapsulated housing (2) and / or the bushing (3) are filled with clean air.

12. A method for increasing the dielectric strength in a high voltage device (1) according to any one of claims 1 to 11, comprising the steps of: The method according to claim 1, characterized in that the at least one electrode (5) at free potential surrounded by the at least one bushing (3) for the at least one live conductor (4) brought into and / or brought out of the encapsulation housing (2) of the high-voltage device (1) has an increased dielectric strength compared to a bushing (3) without the electrode (5) at free potential.

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