Vacuum interrupter and high-voltage switching assembly

Abstract

A vacuum interrupter includes a housing having at least one annular ceramic insulating element which forms a vacuum chamber. A contact system has two contacts which are movable relative to one another. A capacitive element has two electrodes and a dielectric material disposed between the electrodes. The capacitive element is form-lockingly mounted on the insulating element and has a capacitance between 400 pF and 4000 pF. A high-voltage switching assembly including the vacuum interrupter is also provided.

Claims

1. A vacuum interrupter, comprising: a housing having at least one annular ceramic insulating element forming a vacuum chamber; a contact system having two contacts being moveable relative to one another; a capacitive element having two electrodes and a dielectric material disposed between said electrodes, said capacitive element being form-lockingly mounted on said insulating element, and said capacitive element having a capacitance of between 400 pF and 4000 pF; and a resistive element disposed on said at least one insulating element in addition to said capacitive element.

2. The vacuum interrupter according to claim 1, wherein said at least one insulating element has a surface, said capacitive element includes a dielectric material, and at least said dielectric material is applied in a layered configuration to said surface of said at least one insulating element.

3. The vacuum interrupter according to claim 1, wherein said at least one insulating element has an outer surface, and said capacitive element is disposed on said outer surface of said at least one insulating element.

4. The vacuum interrupter according to claim 1, wherein said capacitive element and said resistive element are connected in series.

5. The vacuum interrupter according to claim 1, wherein said resistive element is form-lockingly connected to said at least one insulating element.

6. The vacuum interrupter according to claim 1, wherein said resistive element has a resistance of between 100 ohms and 1500 ohms.

7. The vacuum interrupter according to claim 1, wherein said resistive element has a resistance of between 10.sup.8 and 10.sup.15 ohms.

8. The vacuum interrupter according to claim 1, wherein said at least one insulating element has a surface, said dielectric material is applied to said surface of said at least one insulating element as a layer, and said layer has a thickness of from 5 μm to 150 μm.

9. The vacuum interrupter according to claim 1, wherein said at least one insulating element has a surface, said dielectric material is applied to said surface of said at least one insulating element as a layer, and said layer has a thickness of from 1 mm to 5 mm.

10. The vacuum interrupter according to claim 1, wherein said at least one insulating element has one upper and one lower end face relative to an extension of said at least one insulating element along a switching axis, and said electrodes are disposed on said one upper and said one lower end face of said at least one insulating element.

11. The vacuum interrupter according to claim 10, wherein said at least one insulating element includes a plurality of insulating elements, and said electrodes are integrated in soldered connections between said insulating elements.

12. The vacuum interrupter according to claim 1, wherein said at least one insulating element has an outer surface, and one of said electrodes is applied to said outer surface of said at least one insulating element as a layer.

13. The vacuum interrupter according to claim 12, wherein said capacitive element is disposed on said outer surface of said at least one insulating element in an alternating layered configuration of one of said electrodes, said dielectric material and another of said electrodes.

14. The vacuum interrupter according to claim 1, wherein said dielectric material contains a ferro-electric material, titanate or barium titanate.

15. A high-voltage switching assembly, comprising: the vacuum interrupter according to claim 1; and a further interrupter unit connected in series with said vacuum interrupter.

16. The high-voltage switching assembly according to claim 15, wherein said further interrupter unit is a vacuum interrupter or a gas-insulated switch.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows an equivalent circuit diagram of a high-voltage switching assembly according to the prior art, having parallel-connected control elements,

(2) FIG. 2 shows a high-voltage switching assembly having two series-connected interrupter units, which incorporate integrated control elements,

(3) FIG. 3 shows a cross-sectional view of a vacuum interrupter having resistive and capacitive control elements which are integrated on the surfaces of insulating elements,

(4) FIG. 4 shows an equivalent circuit diagram of the assembly of capacitive and resistive elements for the vacuum interrupter according to FIG. 3,

(5) FIG. 5 shows a cross-sectional view of a vacuum interrupter according to FIG. 1, having control elements in the upper and lower region of the vacuum interrupter,

(6) FIG. 6 shows an equivalent circuit diagram of control elements for the vacuum interrupter according to FIG. 5,

(7) FIG. 7 shows a vacuum interrupter according to FIG. 1, having control elements according to the equivalent circuit diagram shown in FIG. 8,

(8) FIG. 8 shows an equivalent circuit diagram of control elements for the vacuum interrupter according to FIG. 7,

(9) FIG. 9 shows a vacuum interrupter according to FIG. 1, wherein the capacitive element is applied to the insulating element in the form of an alternating layer,

(10) FIG. 10 shows an enlarged section of the layered sequence, from section X in FIG. 9, and

(11) FIG. 11 shows an equivalent circuit diagram of the control element, according to the vacuum interrupter shown in FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

(12) FIG. 1 shows a series-connected arrangement of two interrupter units 32 according to the prior art. Although these interrupter units 32 can be gas-insulated switches, they can also be vacuum interrupters. Control elements 34 are interconnected in parallel with the series-connected interrupter units 32, in order to protect the individual interrupter units 32 in this series-connected arrangement against overloading. To this end, resistors or capacitors are employed, which can be connected in parallel, but also in series. Voltages are thus divided between the individual interrupter units 32, and any overload is prevented.

(13) FIG. 2 represents a configuration in which an interrupter unit 32, in the form of a vacuum interrupter 2, is connected in series with a further interrupter unit 32. The vacuum interrupter 2 incorporates control elements 34, which are configured in the form of capacitive elements 12 and are integrated in the vacuum interrupter 2, as described in greater detail with reference to FIG. 3.

(14) FIG. 3 shows a cross-sectional view of a vacuum interrupter 2 having a housing 3, wherein the housing 3 incorporates a plurality of insulating elements 4 and a centrally arranged metal shield 5. The metal shield 5 is arranged in the housing 3 such that it is mounted in the position in which the contacts 9 and 10 which, in combination, constitute a contact system 8, are mounted in a moveable arrangement along a switching axis 24.

(15) The insulating elements 4 are essentially cylindrically configured, and are also stacked one on top of another along the switching axis 24 such that, along this switching axis 24, which also constitutes the cylinder axis, they constitute a cylinder. The individual insulating elements 4 are connected in a mutually form-locking manner wherein, in the majority of cases, a soldered connection is prevalent. The housing 3 which encloses the contact system 8 constitutes a vacuum chamber 8 which, overall, is sealed vis-à-vis the atmosphere in a vacuum-tight manner.

(16) In schematic terms, a conventional vacuum interrupter 2 according to the prior art is thus constituted. The present vacuum interrupter 2 differs from the latter, in that control elements 34 are arranged on surfaces 20, 21 of the insulating elements 4, wherein at least one capacitive element 12 is fitted to a surface 20, 21 of the insulating element 4. It is not necessary for an explicit distinction to be drawn between an inner surface 21 and an outer surface 20 of the insulating element, wherein, in many cases, it is appropriate for the capacitive element 12 to be fitted to the outer surface 20 of the insulating element 4.

(17) Electrodes 14 are provided, which are preferably arranged between end faces 25 and 26 of the insulating elements 4, along the switching axis 24. The electrodes 14 can be extensions of soldering surfaces 27, which are employed for the connection of the individual insulating elements 4. The electrodes 14, considered radially to the axis 24, thus project to a degree beyond the respective end faces 25 and 26 of the insulating elements 4 such that, between these projecting overhangs of the electrodes 14, a dielectric material 16 is arranged on the outer surface 20 of the insulating element 4, which is contact-connected with the electrodes 14. The electrodes 14, which are contact-connected with the dielectric material 16, constitute the capacitive element 12, in combination with the latter.

(18) It is moreover appropriate that, between electrodes 14 of essentially identical design, a resistive material 19 is also arranged, and is contact-connected with the latter. The resistive element 18 is thus constituted in combination with the electrodes. In the representation according to FIG. 3, on the outer surface 20 of the uppermost insulating element 4, a capacitive element is arranged, which is connected by means of the same electrodes 14 as the resistive element on the inner side of the insulating element 4. A parallel-connected arrangement of the two control elements 34 is thus constituted. In combination with a further resistive element 18 on the adjoining insulating element 4 in FIG. 3, the equivalent circuit diagram according to FIG. 4 is constituted accordingly.

(19) As a material for the capacitive element 12, i.e. the dielectric material 16, for the setting of the desired capacitance, a material having a high ε.sub.r, i.e. a high dielectric constant, is preferably employed. Ferro-electric materials are appropriate for this purpose, particularly a titanate, wherein the employment of barium titanate (ε.sub.r=1000) is preferred. In order to achieve a corresponding capacitance of 400 pF to 4000 pF, the dielectric material can contain the barium titanate in concentrations which, at a specified film thickness of the dielectric material 16 on the insulating element 4, result in the desired capacitance. In particular, a dielectric material is advantageous, in which the barium titanate is embedded in an epoxy resin matrix. The film thickness of the dielectric material 16 of the capacitive element 12 generally lies within the range of 5 μm to 150 μm, rather than the range of 1 mm to 5 mm.

(20) FIG. 5 shows a representation of the vacuum interrupter 2 according to FIG. 1, wherein the arrangement of control elements 32 is symmetrically distributed over the housing 3 or over the insulating elements 4 with respect to the housing 3. This permits a targeted voltage division along the housing 3, between the various insulating elements 4. This involves a series-connected arrangement of a capacitive element 12 and a resistive element 18, as reproduced in the equivalent circuit diagram according to FIG. 6.

(21) FIG. 7 also represents a vacuum interrupter 2 according to FIG. 1, wherein both a capacitive element 12 and a resistive element 18 are fitted to the outer surface 20 of the insulating element 4. Considered in a radial direction, the dielectrically acting material 16 is thus arranged towards the interior, followed by an insulator, which is not described in greater detail here, and thereafter by the resistive material 19. Both the dielectric material 16 and the resistive material 19 are connected to the electrodes 14, according to the equivalent circuit diagram represented in FIG. 8, in a parallel-connected arrangement. On the next insulating element 4 in sequence, a further resistive element 18, as described above, is fitted, such that a further resistive element 18 is connected in series with the parallel-connected arrangement of the resistive element 18 and the capacitive element 12, as represented in FIG. 8 in the form of an equivalent circuit diagram. This circuit arrangement, in an analogous manner to FIG. 5, can also be symmetrically repeated in the lower region of the housing 3. In principle, the representation and the arrangement of resistive or capacitive elements 12, 18 constitute exemplary forms of embodiment. They could also be arranged on all the other insulating elements 4. Thus, in a manner which applies correspondingly to FIGS. 3, 5, 7 and 9, all the control elements 34 can be fitted to either an inner surface 21 or an outer surface 20 of the insulating elements 4.

(22) FIG. 9 represents an alternative configuration of the capacitive element 12. Alternating layers of the electrode 14 and the dielectric material 16 are radially wound about the outer surface 20 of the insulating element 4. An enlarged representation of section X in FIG. 9 is shown in FIG. 10. The sequential layers of the electrode 14 and the dielectric material 16 on the outer surface 20 can be seen here. A dielectric material 16 is thus embedded, on either side, in a layer of conductive electrode material, in the form of the electrode 14. In this manner, the correspondingly desired capacitances of the control element 34 can be more accurately set by the number of individual layers. The corresponding equivalent circuit diagram is represented in FIG. 11. In this case, for exemplary purposes only, one capacitance or one capacitive element 12 is represented. The vacuum interrupter represented in FIG. 9 can also be fitted with further control elements, as represented in FIGS. 3, 5 and 7, in any combination required, both internally and externally.

LIST OF REFERENCE NUMBERS

(23) 2 Vacuum interrupter 3 Housing 4 Insulating element 5 Metal shield 6 Vacuum chamber 8 Contact system 9 Moveable contact 10 Fixed contact 12 Capacitive element 14 Electrodes 16 Dielectric material 18 Resistive element 19 Resistive material 20 Outer surface of insulating element 21 Inner surface 22 Layer of dielectric material 24 Switching axis 25 Upper end face 26 Lower end face 27 Soldering surfaces 28 Switching assembly 32 Interrupter unit 34 Control element 36 Series-connected arrangement of power interrupter chambers