Power switch having a vacuum interrupter chamber

Abstract

The invention relates to a power switch (1). The power switch (1) comprises: a vacuum interrupter chamber (3); metal holders (5, 7) arranged on opposite sides of the vacuum interrupter chamber (3); a housing (9) having a housing wall (25) which is spaced apart from external surfaces (27 to 29) of the vacuum interrupter chamber (3) and the holders (5, 7) so as to be arranged around said external surfaces (27 to 29); a plastics casing (11) which is arranged on the external surface (27) of the vacuum interrupter chamber (3) and on portions (28.1, 29.1) of the external surfaces (28, 29) of both holders (5, 7); and a volume (31) filled with an insulating gas (33) between the plastics casing (11) and the housing wall (25).

Description

[0001] The invention relates to a circuit breaker with a vacuum interrupter chamber. A vacuum interrupter chamber is understood here as an evacuatable vacuum tube in which switching operations are performed.

[0002] In such circuit breakers, switching contact elements that can be moved relative to one another are arranged in the vacuum interrupter chamber, such as e.g. from EP 1 443 537 A1, to prevent or reduce a switching arc when separating the switching contact elements. The switching chamber is often arranged within a housing in an insulating gas, which is compressed under high pressure to increase its dielectric strength. This allows for the metallic components in the housing to be arranged closer together, thus saving installation space.

[0003] The invention is based on the object of providing an improved circuit breaker with a vacuum interrupter chamber.

[0004] The object is achieved according to the invention by a circuit breaker having the features of claim 1.

[0005] Advantageous embodiments of the invention are the subject of the subclaims.

[0006] A circuit breaker according to the invention comprises a vacuum interrupter chamber, metallic supports arranged on opposite sides of the vacuum interrupter chamber, a housing with a housing wall arranged around the outer surfaces of the vacuum interrupter chamber and the supports at a distance from these outer surfaces, a plastic sleeve arranged on the outer surface of the vacuum interrupter chamber and on portions of the outer surfaces of both supports, and a volume filled with an insulating gas between the plastic sleeve and the housing wall. The housing wall is made, for example, of an electrically insulating material, such as a ceramic material or a glass-fiber-reinforced plastic.

[0007] On the one hand, the plastic casing can save insulating gas by supporting the function of the insulating gas. On the other hand, a plastic casing with a high dielectric strength can reduce the pressure of the insulating gas, so that sufficient dielectric strength of the system consisting of the plastic casing and the insulating gas can be achieved even at reduced pressure. This eliminates the need for pressure vessel components in the interrupter unit of the circuit breaker. In addition, gas monitoring, which would otherwise be necessary, can be eliminated or implemented much more easily, since there is no need to immediately shut down the system if leaks occur and the resulting drop in pressure. Cost advantages also arise from the simplification or elimination of components and assemblies, as well as the elimination of complex component testing.This also results in lower maintenance costs. Another important technical advantage is that the circuit breaker's instantaneous switching capability is ensured even in the event of a sudden drop in the insulating gas pressure.

[0008] Accordingly, in one embodiment of the invention, the plastic sheath is made of a plastic that has a higher dielectric strength than the insulating gas. For example, the plastic sheath is made of silicone.

[0009] In a further embodiment of the invention, the insulating gas is dehumidified air or carbon dioxide. These insulating gases are environmentally friendly, but have a lower insulating effect than, for example, sulfur hexafluoride. The plastic sheath is therefore particularly advantageous when using these insulating gases to increase dielectric strength.

[0010] The plastic shell is a plastic layer injected or cast onto the outer surface of the vacuum interrupter chamber and parts of the outer surfaces of the holders. This advantageously enables precise manufacturing of the plastic shell.

[0011] Alternatively, the plastic sleeve is a plastic tube slid over the outer surface of the vacuum interrupter chamber and the outer surfaces of the brackets. This allows the plastic sleeve to be manufactured without the need for a mold for injection molding or casting the plastic sleeve.

[0012] In a further embodiment of the invention, the plastic sheath has a varying thickness. This allows the thickness of the plastic sheath to be adapted to local dielectric strength requirements. For example, the plastic sheath is made thicker near the edges of the vacuum interrupter chamber or the mounting brackets than in other areas.

[0013] In a further embodiment of the invention, the circuit breaker has at least one field control element arranged between the plastic casing and the outer surface of the vacuum interrupter chamber and / or a portion of the outer surface of a holder. A field control element is an element that locally modifies the field strength of an electric field. Field control elements can advantageously prevent particularly high local electric field strengths.

[0014] For example, at least one field control element is made of an electrically conductive plastic, such as a carbon black-filled silicone elastomer. Such field control elements can advantageously be manufactured by injection molding or casting, particularly together with a plastic sheath embodied as a plastic layer. If the plastic sheath is embodied as a plastic tube, the field control elements can be integrated into the plastic tube.

[0015] Furthermore, at least one field control element is preferably arranged at one end of a holder. This advantageously prevents large local electric field strengths in the region of the holder end.

[0016] In a further embodiment of the invention, one end of the vacuum interrupter chamber extends into each holder. This particularly simplifies the manufacture of the plastic casing in the transition areas between the vacuum interrupter chamber and the holders.

[0017] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. FIG 1 a first embodiment of a circuit breaker, FIG 2 a second embodiment of a circuit breaker.

[0018] Corresponding parts are provided with the same reference numerals in the figures.

[0019] Figure 1 (FIG 1) shows a first embodiment of a circuit breaker 1 in a sectional view. The circuit breaker 1 comprises, among other things, a vacuum interrupter chamber 3, tubular metallic supports 5, 7, a housing 9, and a plastic enclosure 11.

[0020] The holders 5, 7 are arranged on opposite sides of the vacuum interrupter chamber 3 and serve in particular as a base for the vacuum interrupter chamber 3. A metallic interrupter chamber end 13, 15 of the vacuum interrupter chamber 3 projects into each holder 5, 7. A first switching contact element 17 is arranged on a first holder 5 and projects into the vacuum interrupter chamber 3 through a first interrupter chamber opening in a first interrupter chamber end 13. A second switching contact element 19 projects into the vacuum interrupter chamber 3 through a second interrupter chamber opening in the second interrupter chamber end 15 and is movable relative to the first switching contact element 17 by a mechanism not shown. Regions of the vacuum interrupter chamber 3 surrounding the switching contact elements 17, 19 each have an insulating section 21, 23 made of an electrically insulating material, for example a ceramic material.The insulation sections 21, 23 are arranged on opposite sides of a metallic central region of the vacuum interrupter chamber 3.

[0021] The housing 9 comprises a housing wall 25, which is arranged around an outer surface 27 of the vacuum interrupter chamber 3 and outer surfaces 28, 29 of the holders 5, 7, spaced apart from these outer surfaces 27 to 29. The housing wall 25 is designed as an insulating tube made of an electrically insulating material, for example, a ceramic material or a glass-fiber-reinforced plastic, and arranged between metal flanges. The circuit breaker 1 is thus designed in the so-called live tank design, in contrast to the so-called dead tank design with a grounded metallic housing.

[0022] The plastic sleeve 11 is arranged on the outer surface 27 of the vacuum interrupter chamber 3 and on partial areas 28.1, 29.1 of the outer surfaces 28, 29 of both holders 5, 7. A volume 31 between the plastic sleeve 11 and the housing wall 25 is filled with an insulating gas 33, for example, dehumidified air or carbon dioxide.

[0023] The plastic sheath 11 is made of a plastic that has a higher dielectric strength than the insulating gas 33. For example, the plastic sheath 11 is made of silicone.

[0024] The plastic casing 11 has a varying thickness. For example, the plastic casing 11 is thicker in the transition areas from the outer surface 27 of the vacuum interrupter chamber 3 to the partial areas 28.1, 29.1 of the outer surfaces 28, 29 of the holders 5, 7 than in adjacent areas.

[0025] The plastic sleeve 11 is, for example, a plastic layer injection-molded or cast onto the outer surface 27 of the vacuum interrupter chamber 3 and the partial areas 28.1, 29.1 of the outer surfaces 28, 29 of the holders 5, 7. Alternatively, the plastic sleeve 11 is a plastic tube pushed over the outer surface 27 of the vacuum interrupter chamber 3 and the partial areas 28.1, 29.1 of the outer surfaces 28, 29 of the holders 5, 7.

[0026] Figure 2 (FIG 2 ) shows a second embodiment of a circuit breaker 1 in a sectional view. This embodiment differs from the one shown in Figure 1shown embodiment only by annular field control elements 35 to 38, which in the case of the field control elements 36, 37 are arranged between the plastic shell 11 and the outer surface 27 of the vacuum interrupter chamber 3 or in the case of the field control elements 35, 38 between the plastic shell 11 and the outer surface 27 of the vacuum interrupter chamber 3 and a partial area 28.1, 29.1 of the outer surface 28, 29 of a holder 5, 7.

[0027] A first field control element 35 is arranged at a holder end 5.1 of the first holder 5 facing the vacuum interrupter chamber 3, a second field control element 36 is arranged at an end of a first insulation section 21 facing away from the first holder 5, a third field control element 37 is arranged at an end of the second insulation section 23 facing away from the second holder 7, and a fourth field control element 38 is arranged at a holder end 7.1 of the second holder 7 facing the vacuum interrupter chamber 3. However, field control elements 35 to 38 can also be arranged on other regions of the outer surfaces 27 to 29.

[0028] The field control elements 35 to 38 are each made of an electrically conductive plastic, for example, a carbon black-filled silicone elastomer. If the plastic sleeve 11 is a plastic tube that is pushed over the outer surface 27 of the vacuum interrupter chamber 3 and the partial areas 28.1, 29.1 of the outer surfaces 28, 29 of the holders 5, 7, the field control elements 35 to 38 can be integrated into the plastic tube, for example.

Claims

1. Circuit breaker (1), comprising - a vacuum interrupter chamber (3), - metal holders (5, 7) arranged on opposite sides of the vacuum interrupter chamber (3), - a housing (9) with a housing wall (25), which is arranged at a distance from outer surfaces (27 to 29) of the vacuum interrupter chamber (3) and the holders (5, 7), around these outer surfaces (27 to 29), - a plastic enclosure (11), arranged on the outer surface (27) of the vacuum interrupter chamber (3) and on partial regions (28.1, 29.1) of the outer surfaces (28, 29) of both holders (5, 7), and - a volume (31) filled with an insulating gas (33) between the plastic enclosure (11) and the housing wall (25), characterized in that the plastic enclosure (11) is a layer of plastic extruded or moulded onto the outer surface (27) of the vacuum interrupter chamber (3) and the partial regions (28.1, 29.1) of the outer surfaces (28, 29) of the holders (5, 7), or in that the plastic enclosure (11) is a plastic tube pushed over the outer surface (27) of the vacuum interrupter chamber (3) and the partial regions (28.1, 29.1) of the outer surfaces (28, 29) of the holders (5, 7).

2. Circuit breaker (1) according to Claim 1, wherein the plastic enclosure (11) is produced from a plastic which has a higher dielectric strength than the insulating gas (33).

3. Circuit breaker (1) according to Claim 1 or 2, wherein the plastic enclosure (11) is produced from a silicone.

4. Circuit breaker (1) according to one of the preceding claims, wherein the insulating gas (33) is dehumidified air or carbon dioxide.

5. Circuit breaker (1) according to one of the preceding claims, wherein the plastic enclosure (11) has a varying thickness.

6. Circuit breaker (1) according to one of the preceding claims with at least one field control element (35 to 38), which is arranged between the plastic enclosure (11) and the outer surface (27) of the vacuum interrupter chamber (3) and / or a partial region (28.1, 29.1) of the outer surface (28, 29) of a holder (5, 7).

7. Circuit breaker (1) according to Claim 6, wherein at least one field control element (35 to 38) is produced from an electrically conductive plastic.

8. Circuit breaker (1) according to Claim 6 or 7, wherein at least one field control element (35 to 38) is arranged at a holder end (5.1, 7.1) of a holder (5, 7).

9. Circuit breaker (1) according to one of the preceding claims, wherein an interrupter chamber end (13, 15) of the vacuum interrupter chamber (3) protrudes into each holder (5, 7).

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