EP3297014A1 - High voltage switching apparatus and switching circuit using a high voltage switching apparatus and method for producing a high voltage switching apparatus - Google Patents

Abstract

The invention relates to a high voltage switching device with a vacuum chamber and a switchgear with a high voltage switching device. Moreover, the invention relates to a method for producing a high-voltage switching device with a vacuum chamber. The high-voltage switching device has a potting housing 1 made of a casting resin, which surrounds the housing body 3 of the vacuum chamber 2, which has a fixed contact 4A and a movable contact 5A, wherein between the inner wall of the potting 1 and the outer wall of the housing body 3 of the vacuum chamber. 2 an intermediate layer 3A is provided. The high-voltage switching device is characterized in that this intermediate layer is a casting resin layer 3A, wherein the glass transition temperature of the casting resin layer is between 10 and 40 ° C. In such a construction, in tests no cracks in the coating or wrapping of the housing body of the vacuum chamber and no external flashovers on the housing body have been shown.

Description

The invention relates to a high voltage switching device with a vacuum chamber and a switchgear with a high voltage switching device. Moreover, the invention relates to a method for producing a high-voltage switching device with a vacuum chamber.

In networks of electric power lines switchgears are used, with which the electrical energy is distributed. Switchgear units have switchgear that establish or disconnect an electrically conductive connection between electrical contacts. In high-voltage or medium-voltage networks, high-voltage switching devices are used that meet the electrical requirements for high voltages in high-voltage or medium-voltage networks. The voltages of the high voltage grids are generally between 60 and 52 kV and the medium voltage grids between 1kV and 52 kV.

There are high-voltage switching devices are known which have a vacuum chamber in which the electrical contacts are arranged. But there are also switching devices are known in which the electrical contacts in a gas atmosphere of insulating gas, such as SF ₆ , are located. The use of vacuum chambers, in contrast to filled with insulating gas chambers has the advantage that load currents and short-circuit currents can be interrupted in a relatively small volume, without the risk of emission of hot switching gases. In air-insulated switchgear, a particularly long insulation distance is required, which is why these switchgear take up very much space. Vacuum chambers are used in switching devices with circuit breakers, earthing switches, circuit breakers or switch disconnectors.

Switchgear with vacuum chamber are for example from the DE 31 12 776 A1 and DE 40 27 723 A1 known. The known vacuum chambers have a housing body in which an immovable switching contact and a movable switching contact are arranged.

The movable switching contact is actuated by an actuating unit. The drive of the actuator can be done with an electric drive unit.
To reduce the size of the high-voltage switchgear and thus the switching devices having switchgear, the vacuum chamber is inserted into a casting mold and sealed with a potting compound, such as epoxy, so that the vacuum chamber is enclosed by a solid potting after curing of the potting compound.

If the high-voltage switching device flows through current during operation, the power loss is released in the form of heat. As a result of the heat, the components of the housing body of the vacuum chamber, which may be made of ceramic or metallic materials, such as copper, expand more than the solid potting housing. As a result, mechanical stresses and associated fine cracks in the solid plastic potting arise. The life of the switching device can thus be significantly reduced. In addition, unexpected rollovers can occur.

For this reason, in the prior art vacuum chambers are provided in high-voltage switching devices with an outer silicone layer or welded with a shrink tube. The coating of silicone or the use of a shrink tube should not only prevent the formation of mechanical stresses, but also provide the advantage that a sufficient isolation distance between the fixed and the movable switch contact along the outside of the vacuum chamber is made. So outer flashovers on the vacuum chamber should be avoided.

In practice, it has been shown that the coating of the vacuum chamber, especially at higher voltages, for example voltages from 20 kV to earth or from 36 kV of chained voltage, is a critical element of the switching device. Experiments have shown that even silicone-coated vacuum chambers can cause flashovers between the silicone coating and the vacuum chamber.

The invention has for its object to reduce the risk of flashovers in high-voltage switchgear and switchgear with high-voltage switchgear. Another object of the invention is to provide a method with which a high-voltage switching device can be produced with improved electrical properties.

The solution of these objects is achieved according to the invention with the features of the independent claims. The dependent claims relate to preferred embodiments of the invention.

Extensive investigations on various high-voltage switching devices have shown insufficient adhesion of the silicone layer to the housing body of the vacuum chamber. It has been found that the insufficient adhesion for the formation of flashovers between the fixed and movable switching contact along the housing body of the vacuum chamber between the silicone layer and the housing body is the cause.

The high-voltage switching device according to the invention comprises a casting housing made of a casting resin, which encloses the housing body of the vacuum chamber, which has a fixed contact, which may be a switching or isolating contact, and a movable contact, which may be a switching or isolating contact, wherein between the inner wall of the potting and the outer wall of the housing body of the vacuum chamber, an intermediate layer is provided. The high-voltage switching device is characterized in that this intermediate layer is a casting resin layer, wherein the glass transition temperature of the casting resin layer is between 10 and 40 ° C. Preferably, the glass transition temperature of the casting resin layer is between 20 and 30 ° C. The glass transition temperature gives an indication of the dimensional stability of the plastic when exposed to heat. It indicates the temperature at which a plastic changes from a liquid or rubber-elastic, flexible state to a glassy or hard-elastic, brittle state. The coating or enclosure of the vacuum chamber has greater flexibility than the fixed potting of the switching device. In such a structure, in tests have no cracks in the Coating or wrapping of the housing body shown. Further, due to the good adhesion of the intermediate layer to the vacuum chamber, flashovers between the fixed and movable switch contacts along the vacuum chamber were prevented.

A preferred embodiment provides that the modulus of elasticity of the casting resin of the casting resin layer of the vacuum chamber is less than 1000 MPa. Preferably, the modulus of elasticity of the cast resin layer is greater than 100 MPa, more preferably greater than 500 MPa. A cast resin layer having a tensile strength of less than 20 MPa has proved to be particularly advantageous. The casting resin is preferably an epoxy resin.

In a particularly preferred embodiment, the high-voltage switching device comprises a plastic body which is enclosed by the potting housing. In the plastic body, an operating unit for the movable contact of the vacuum chamber is arranged. The housing body of the vacuum chamber is preferably in an upper half of the housing in the installed position of the switching device and the plastic body is arranged in a lower half of the casting housing.

The plastic body may consist of one or more plastic elements which are interconnected. Advantageously, the plastic body consists of several plastic elements that can be easily and inexpensively manufactured by injection molding and then can be connected together. Individual plastic elements can be plugged into each other and / or glued or welded together. With the use of a plastic body not only the electrical properties of the switching device can be improved, but also its manufacture can be simplified.

In a high-voltage switching device, in which such a plastic body is used, the intermediate layer allows a secure sealing of the vacuum chamber with respect to the plastic body, which is advantageous for the production of the high-voltage switching device, since in injection molding resin is not in a gap between the vacuum chamber and plastic body can get.

For secure sealing, the plastic body in a particularly preferred embodiment on the top of projections or cutting edges, which are cut into the flexible casting resin layer on the underside of the vacuum chamber.

The switchgear according to the invention has one or more switching devices according to the invention.

The inventive method for producing the high-voltage switching device according to the invention provides that the surface of the housing body of the vacuum chamber is processed to increase the surface roughness before a Gießharzschicht is applied to the outer wall of the housing body of the vacuum chamber. The surface of the housing body is preferably machined so that the surface roughness is greater than 20 microns, preferably between 20 microns and 40 microns. As a result, optimum adhesion between the casting resin and the housing body is given. Machining the surface of the housing body of the vacuum chamber with glass bead has proven to be particularly advantageous. The surface of the case body should also be degreased.

The cast resin layer may be applied to the housing body of the vacuum chamber by the method known in the art. Preferably, the casting resin layer is applied by a pressure gelling or vacuum method so that the formation of air bubbles can be avoided.

After the casting resin layer has been applied to the outer wall of the housing body of the vacuum chamber, the surface of the cast resin layer is processed to achieve optimum adhesion with the potting housing. The surface of the casting resin layer is preferably processed in such a way that the surface roughness is greater than 90 μm, preferably between 90 μm and 120 μm. It has proven particularly advantageous to machine the surface of the casting resin layer with a corundum jet method. Such a blasting process belongs to the state of the art. The surface of the casting resin layer should also be degreased. Subsequently, the vacuum chamber is inserted into a casting mold. For the production of the high-voltage switchgear a mold can be provided which corresponds in shape and dimensions to the contour of the potting of the switching device. In the casting mold and the plastic body can be used. Then, the gap between the inner wall of the casting mold and the outer wall of the vacuum chamber is potted with a casting resin. As a result, the potting is created. In the plastic body, a cavity for installation of the operating unit for the movable switching contact may be provided. Finally, further assemblies or components of the high-voltage switching device, for example, the operating unit or with the fixed and movable switching contact to be joined conductor parts in the potting or the plastic body can be used.

In the following an embodiment of the invention will be explained in more detail with reference to the drawings.

Fig. 1

ein Ausführungsbeispiel des erfindungsgemäßen Hochspannungs-Schaltgerätes in teilweise geschnittener perspektivischer Darstellung,

Fig. 2

eine teilweise geschnittene perspektivische Darstellung der Vakuumkammer des erfindungsgemäßen Hochspannungs-Schaltgerätes und

Fig. 3

eine Explosionsdarstellung von weiteren Bauteilen des erfindungsgemäßen Hochspannungs-Schaltgerätes.

Show it:

Fig. 1

An embodiment of the high-voltage switching device according to the invention in a partially sectioned perspective view,

Fig. 2

a partially sectioned perspective view of the vacuum chamber of the high-voltage switching device according to the invention and

Fig. 3

an exploded view of other components of the high-voltage switching device according to the invention.

Fig. 1 shows the essential components of the invention of the high-voltage switching device, while Fig. 2 the vacuum chamber of the switching device shows. The corresponding parts are provided in the figures with the same reference numerals. The vacuum chamber may include, for example, a vacuum switching chamber for switching load currents or short-circuit currents in a circuit breaker or a vacuum isolation chamber for a circuit breaker or earthing switch or combined Be a switch. The invention will be described below with reference to a circuit breaker.

The high-voltage switching device has a potting housing 1, which has a housing half 1A in the normal installation position and a lower housing half 1B. In the upper casing half 1A is a vacuum chamber 2 with a cylindrical casing body 3, which receives an upper, fixed switching contact 4A and a lower, movable switching contact 5B. The housing body 3 of the vacuum chamber 2 may consist of several components of metallic or ceramic materials. By closing or opening the contacts 4A, 5A, the current path can be closed or interrupted, i. For example, a load current to be switched. In the lower housing half 1B sits a plastic body 16, in which a chamber 6 is formed, in which an actuating unit for the movable switching contact is arranged. The chamber 6 is filled with an insulating liquid. The actuator will be described later in detail.

The injection-molded housing 1 of the high-voltage switching device produced by injection molding may consist of a conventional casting resin. Preferably, the potting housing made of epoxy resin. The casting resin has a glass transition temperature (Tg) which is between 80 and 120 ° C. The maximum tensile stress of the casting resin (tensile strength) is greater than 60 MPa and the elongation at break of the casting resin (tensile strength) is less than 3%. The elastic modulus (modulus of elasticity) of the casting resin is greater than 8000 MPa. The potting housing is a solid housing body.

In the space between the outer wall of the vacuum chamber 2 and the inner wall of the fixed potting 1 is an intermediate layer 3A made of a casting resin, which is more flexible than the casting resin of the potting 1.

The flexible casting resin has a glass transition temperature (Tg) which is between 10 and 40 ° C. The maximum tensile stress (tensile strength) of the casting resin is less than 20 MPa and the elongation at break (tensile strength) greater than 9%. The elastic modulus (modulus of elasticity) of the casting resin is less than 1000 MPa. Preferably, the modulus of elasticity of Casting resin greater than 100 MPa, more preferably greater than 500 MPa, in particular about 600 MPa. As a casting resin, the material known under the name Araldite® (Huntsman Advanced Materials), in particular Araldite® S-HCEP or Araldite® CW 1491 / HW 1491, has proven to be particularly advantageous.

To produce the high-voltage switching device, a layer of the abovementioned material is applied to the housing body 3 of the vacuum chamber 2. The application of the cast resin layer 3A can be done by the methods known in the art. Fig. 2 shows the housing body 3 of the vacuum chamber 2 with the outer casting resin layer 3A, which extends over the cylindrical peripheral surface and on the upper side and lower side of the housing body of the vacuum chamber in the installed position.

Hereinafter, the operating unit for the movable switching contact and other components and components of the high-voltage switching device with reference to the FIGS. 1 to 3 described in detail.

The displaceable in the axial direction of the vacuum chamber 2 switching contact 5A is part of a switching contact element 5, which has a shank 5B, which extends from the vacuum chamber 2 in the chamber filled with insulating liquid 6. The shaft 5B of the movable switching contact element 5 is sealed vacuum-tight with respect to the housing body 3 of the vacuum chamber 2 with a sealing arrangement, not shown. The lower end of the shaft 5B is connected via an insulating body 7 with an actuator 8, which extends from the liquid-filled chamber 6. By actuating the actuating member 8, the movable switching contact element 5 can be moved axially, so that the contacts 4A, 5A are closed or opened.

The actuator 8 has an upper, hollow cylindrical portion 8A, which is located in the chamber 6 and a lower, pin-shaped portion 8B, which is longitudinally displaceably guided in the cylinder space of the upper portion and extending from the chamber 6. In this case, the upper end portion of the lower portion 8B is supported on a compression spring 9 in the cylinder space of the upper portion 8A. If the lower one Section 8 B is moved, also shifts the upper portion 8 A, so that the movable switching contact element 5 is displaced axially. The compression spring 9 serves to damp the shocks during the actuation of the actuating member 8. The drive of the actuator 8 is effected with a drive unit, not shown, which moves the lower portion 8 B in the axial direction.

The actuating member 8 is sealed liquid-tight with respect to the potting housing 1 with a sealing arrangement 10. The sealing assembly 10 has a bellows 11 which surrounds the upper portion 8A of the actuator 8, wherein the upper end of the bellows 11 is liquid-tightly connected to the upper portion 8A of the actuator 8. The lower end of the bellows 11 is sealed liquid-tight against the potting 1. The bellows 11 and the actuator 8 are placed at ground potential. At the bottom, the housing body 1 has an opening 12, which is closed by a cover 13 liquid-tight.

The liquid-filled chamber 6 has an upper and lower chamber half 6A, 6B in the installed position. In the upper chamber half 6A is a movable conductor part 12, for example a copper strip, which is connected to the shaft 5B of the movable switching contact element 5. The movable conductor part 12 is electrically connected to further conductor parts 13 forming the current path, which however are only partially shown. Also, the fixed switching contact element 4 is connected to other guide parts 14 only partially shown, which are also used in the potting 1 or placed on the potting.

The plastic body 16 in the lower housing half 1B of the potting housing 1 is composed of a plurality of plastic elements 16A, 16B, 16C. Fig. 3 shows the plastic elements 16A, 16B, 16C in an exploded view. The plastic body 16 has in the upper half of the chamber 6A an upper shell-shaped plastic element 16A and a lower, shell-shaped plastic elements 16B which surround the movable conductor part 12, and has in the lower chamber half 6B a cylindrical plastic element 16C which surrounds the bellows 11. The plastic members 16A, 16B, 16C are formed so that they can be assembled properly. They are tightly inserted into each other and / or glued or welded together. All plastic elements 16A, 16B, 16C have rounded corners or edges.

The two plastic elements 16A, 16B in the upper chamber half 6A are made of an electrically conductive plastic, for example, the plastic may be mixed with conductive carbon. Since these plastic elements 16A, 16B can assume the same potential as the movable conductor part 12 or other conductor parts in the chamber, the electric field becomes more homogeneous to the outside.

The plastic element 16C in the lower chamber half 6B, which is not made of a conductive plastic, can not conduct a potential. This plastic element 6C is used for safe insulation of live parts in the chamber 6 with respect to the lying at ground potential actuator 8. To increase the creepage path, the plastic element 16C on the outside of fins 17.

The cover 13 of the potting housing 1, which closes the liquid-filled chamber 6, is sealed in a liquid-tight manner with respect to the cylindrical plastic part 16C with a sealing ring 18 located between the cover and the plastic part.

The process according to the invention for producing the high-voltage switching device will now be described.

The case body 1 of the vacuum chamber 2 is provided with the above-described flexible casting resin layer 3A. For this purpose, the surface of the housing body 3 is first processed in order to achieve optimum adhesion with the housing body 2. The surface is blasted, for example, with glass ball beads, so that the surface roughness is greater than 20 microns, preferably between 20 microns and 40 microns, and the surface is degreased.

Subsequently, the housing body 1 of the vacuum chamber 2 is inserted into a casting mold, not shown, which may consist of two mold halves, and in the space between the inner wall of the mold halves and the outer wall of the Housing body 3, the casting resin is filled. The coating or coating of the housing body 3 can be done with the known Druckgelierverfahren. The filling pressure should be above 1 bar. Typical values are 3 to 7 bar. So a bubble-free casting can be guaranteed.

After the casting resin has cured and the mold halves have been removed, the surface of the coating or coating is processed in order to achieve optimum adhesion with the cast resin of the solid potting housing 1. The surface of the casting resin layer is processed in such a way that the surface roughness is greater than 90 μm, preferably between 90 μm and 120 μm. The surface treatment can be carried out, for example, with a corundum jet method.

For the production of the potting housing 1 of the switching device, a casting mold, not shown in the figures is used, which is designed such that the shape and dimensions of the potting 1 and the shape and dimensions of the provided with the casting resin layer 3A vacuum chamber 2 and the rest Components of the switching device corresponds. In the upper half of the casting mold, the vacuum chamber 2 is used, wherein between the inner wall of the casting mold and the outer wall of the vacuum chamber 2, a gap 19 remains. In the lower half of the casting mold, the plastic body 16 is used, wherein between the wall of the casting mold and the plastic body 16, a gap 20 remains. Subsequently, the intermediate spaces 19, 20 are cast between casting mold and vacuum chamber or plastic body with a potting material, which has the material properties described above.

The upper plastic element 16A in the upper half of the chamber 6A preferably has at the upper edge a plurality of annular projections or cutting edges 21 which cut into the coating or casing 3A of the housing body 3 of the vacuum chamber 2 during the compression of the components, so that the potting compound for the potting, the in the liquid state has a relatively high viscosity, under pressure can not penetrate into a gap between the housing body 3 of the vacuum chamber 2 and the plastic body 16.

After curing of the potting the movable conductor part 12, the actuator 8, the insulating body 7 and the sealing assembly 10 and optionally other components of the switching device are used in the space enclosed by the plastic body 16 cavity and the cavity is filled with the insulating liquid. Then, the cavity is sealed liquid-tight by placing the cover 13.

Claims (16)

A high-voltage switching device comprising a casting housing (1) of a casting resin enclosing a vacuum chamber (2) having a housing body (3) in which a fixed contact (4A) and a movable contact (5A) are arranged, between the Inner wall of the potting (1) and the outer wall of the housing body (3) of the vacuum chamber (2) an intermediate layer (3A) is provided,
characterized in that
the intermediate layer (3A) is a cast resin layer, wherein the glass transition temperature of the cast resin layer is between 10 and 40 ° C. High-voltage switching device according to claim 1, characterized in that the glass transition temperature of the casting resin layer (3A) is between 20 and 30 ° C. High-voltage switching device according to claim 1 or 2, characterized in that the modulus of elasticity of the casting resin layer (3A) is less than 1000 MPa. High-voltage switching device according to one of claims 1 to 3, characterized in that the modulus of elasticity of the casting resin layer (3A) is greater than 100 MPa, preferably greater than 500 MPa. High-voltage switching device according to one of claims 1 to 4, characterized in that the tensile strength of the casting resin layer (3A) is less than 20 MPa. High-voltage switching device according to one of claims 1 to 5, characterized in that the casting resin is an epoxy resin. High-voltage switching device according to one of claims 1 to 6, characterized in that the potting housing (1) encloses a plastic body (16) in which an actuating unit for the movable contact is arranged, wherein the housing body (3) of the vacuum chamber (2) in a in the installed position of the switching device upper housing half (1A) and the plastic body (16) in a lower housing half (1B) of the potting (1) are arranged and the plastic body (16) at the top projections or cutting edges (21), in the cast resin layer (3A) are cut at the bottom of the plastic body. Switchgear with a high-voltage switching device according to one of claims 1 to 7. Method for producing a high-voltage switching device according to claim 1, characterized in that the method comprises the following method steps: Processing the surface of the housing body (3) of the vacuum chamber to increase the surface roughness, Applying a casting resin layer (3A) on the outer wall of the housing body (3) of the vacuum chamber (2), Working the surface of the cast resin layer (3A) to increase the surface roughness, Inserting the vacuum chamber (2) into a casting mold, Potting the gap between the inner wall of the mold and the outer wall of the vacuum chamber (2) with a casting resin whose glass transition temperature is between 10 and 40 ° C. A method according to claim 9, characterized in that on the outer wall of the housing body (3) of the vacuum chamber (2) a casting resin layer (3A) is applied, whose glass transition temperature is between 10 and 40 ° C. A method according to claim 9 or 10, characterized in that on the outer wall of the housing body (3) of the vacuum chamber (2) a casting resin layer (3A) is applied whose elastic modulus is less than 1000 MPa. Method according to one of claims 9 to 11, characterized in that on the outer wall of the housing body (3) of the vacuum chamber (2) a casting resin layer is applied whose modulus of elasticity is greater than 100 MPa, preferably greater than 500 MPa. Method according to one of claims 9 to 12, characterized in that on the outer wall of the housing body (3) of the vacuum chamber (2) a casting resin layer (3A) is applied, whose tensile strength is less than 20 MPa. Method according to one of claims 9 to 13, characterized in that on the outer wall of the housing body (3) of the vacuum chamber (2) a casting resin layer (3A) made of epoxy resin is applied. Method according to one of claims 9 to 14, characterized in that the casting resin layer (3A) is applied to the housing body (3) of the vacuum chamber (2) by a pressure gelling process. Method according to one of claims 9 to 15, characterized in that the surface of the housing body (3) of the vacuum chamber (2) is machined such that the surface roughness is greater than 20 microns, preferably between 20 microns and 40 μm, and / or the surface of the cast resin layer (3A) is machined such that the surface roughness is greater than 90 μm, preferably between 90 μm and 120 μm.

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