Insulating support assembly for a circuit breaker

Abstract

The application relates to certain embodiments of an improved insulating support assembly for a circuit breaker. One embodiment comprises a strut and two metallic shields. The strut comprises an elongated main body and two metallic inserts. The main body is continuously curved from one end to the other end of the main body, each end of the main body being configured to face a radial direction of its component, the main body being configured to be in a same plane as a plane containing both radial directions of the components; each metallic shield is configured to be assembled to its respective end of the main body through its respective metallic insert and affixed to an outer surface of its respective component with fixing elements, each metallic shield having a C-shaped profile shaped to accommodate the outer surface of its respective component.

Claims

1. An insulating support assembly configured to provide mechanical support and electrical insulation between two components of a circuit breaker, the insulating support assembly comprising a strut and two metallic shields, the strut comprising: an elongated main body made of a vacuum casted epoxy resin having two ends; and two metallic inserts, each insert being partially embedded in a respective end of the main body; wherein the main body is continuously curved with a curvature extending from one end to the other end of the main body, each end of the main body being configured to face a radial direction of the respective component, and the main body being configured to be in a same plane as a plane containing both radial directions of the components; and wherein each metallic shield is configured to be assembled to the respective end of the main body through the respective metallic insert and affixed to an outer surface of the respective component of the circuit breaker by means of fixing elements, each metallic shield having a C-shaped or substantially C-shaped profile shaped to accommodate the outer surface of the respective component.

2. The insulating support assembly according to claim 1, wherein the elongated main body has a C-shaped or substantially C-shaped profile.

3. The insulating support assembly according to claim 2, wherein the C-shaped or substantially C-shaped profiles of the shields are parallel and planes containing the C-shaped or substantially C-shaped profiles of the shields are oriented at an angle of 90° with respect to a plane containing the C-shaped or substantially C-shaped profile of the main body.

4. The insulating support assembly according to claim 2, wherein one of the two C-shaped or substantially C-shaped profiles of the shields and the C-shaped or substantially C-shaped profile of the main body are in a same plane and this plane is oriented to an angle of 90° with respect to a plane containing the other one of the two C-shaped or substantially C-shaped profiles of the shields.

5. The insulating support assembly according to claim 1, wherein an angle θ between the two ends of the main body is comprised between 60° and 180° inclusive.

6. The insulating support assembly according to claim 1, wherein a smallest dimension of a cross section of the main body is larger than a largest dimension of a cross section of the respective metallic insert.

7. The insulating support assembly according to claim 1, wherein at least one metallic shield and the respective metallic insert are integrated into a single metallic element.

8. The insulating support assembly according to claim 1, wherein the elongated main body has an ovoid or circular cross section.

9. The circuit breaker insulation arrangement according to claim 1, comprising at least one insulating support assembly and two components of a circuit breaker, wherein each metallic insert is assembled, through the respective metallic shield, on the outer surface of its respective component in a radial direction of said component.

10. The circuit breaker insulation arrangement according to claim 9, wherein the metallic shields have through-holes for accommodating fixing elements and are attached to the respective components by the fixing elements, each fixing element being recessed in a through-hole so as not to protrude from a surface of the respective metallic shield.

11. The circuit breaker insulation arrangement according to claim 9, wherein at least one metallic shield is housed in a recess in the outer surface of the respective component of the circuit breaker.

12. The circuit breaker insulation arrangement according to claim 9, wherein the two components are two interrupter sub-assemblies, each interrupter sub-assembly containing a switch contact pole.

13. The circuit breaker insulation arrangement according to claim 12, comprising at least three insulating support assemblies.

14. The circuit breaker insulation arrangement according to claim 9, wherein one of the two components is a circuit breaker contact and the other one of the two components is a grading capacitor or a pre-insertion resistor.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1, already described, shows a section view through an area of a gas-insulated circuit breaker according to an exemplary embodiment of the prior art;

(2) FIG. 2, already described, shows a switching chamber arrangement according to an exemplary embodiment of the prior art;

(3) FIG. 3 shows a section view through an area of a gas-insulated circuit breaker according to an exemplary embodiment of the invention;

(4) FIG. 4 shows a switching chamber arrangement of a plurality of insulating support assemblies according to an exemplary embodiment of the invention;

(5) FIG. 5 shows an exploded view of an insulating support assembly according to an exemplary embodiment of the invention;

(6) FIG. 6 shows an exemplary embodiment according to the invention of a metallic shield and its respective metallic insert integrated in a single metallic element;

(7) FIG. 7 shows a perspective top view of a strut according to an exemplary embodiment of the invention;

(8) FIG. 8a shows a perspective lateral view of the strut illustrated in FIG. 7;

(9) FIG. 8b shows another perspective lateral view of the strut illustrated in FIG. 7;

(10) FIG. 9 shows a cross-sectional view as seen along plane A-A of the strut illustrated in FIG. 8a and FIG. 8b;

(11) FIG. 10 shows a perspective lateral view of a circuit breaker insulation arrangement wherein a circuit breaker contact is connected to an element which is a grading capacitor or a pre-insertion resistor;

(12) FIG. 11 shows a cross-sectional detail view of the arrangement illustrated in FIG. 10 as seen along plane B-B.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(13) The insulating support assembly according to the invention can be used to provide mechanical support, as well as alignment and insulation across two components of a circuit breaker.

(14) For example, it can be used to connect two interrupter sub-assemblies, each interrupter sub-assembly containing a switch contact pole, in order to connect the two contact poles across the interrupter gap. Accordingly, the insulating support assembly according to the invention can be used as a gap insulator to provide mechanical support, alignment and electrical insulation across the interrupter gap, while maintaining a minimum radial dimension of the interrupter and of the tank. It allows for a reduction in costs of the interrupter and the tank as a result of smaller radial dimensions. Furthermore, the curved form of the strut increases the strike distance and creepage distance, improving performance under polluted conditions.

(15) As illustrated in FIG. 3, a plurality of insulating support assemblies according to the invention can be used to connect to interrupter sub-assemblies 1, 2. In this embodiment, two insulating support assemblies 12, 22 are arranged across the interrupter gap and the metallic shields are fixed around the perimeter of the interrupter sub-assemblies 1, 2.

(16) In FIG. 4 is illustrated another exemplary of an arrangement according to the invention of three insulating support assemblies 12, 22, 32, each insulating support assembly 12, 22, 32 comprising a strut 120, 122, 132 and two metallic shields 15. The metallic shields 15 are arranged along a circumference U and configured to be assembled and fixed to their respective components (here interrupter sub-assemblies) along this circumference U (in the direction of the bold arrows, which are oriented in a radial direction relative to the longitudinal L direction).

(17) As illustrated in FIG. 5, the insulating support assembly 12 according to the invention comprises a strut 120 and two metallic shields 15. The strut 120 comprises an electrically insulating curved main body 3, made of a vacuum casted epoxy resin, and two metallic inserts 14, each insert being partially embedded at one end of the main body. Each metallic shield 15 is configured to be assembled with its respective metallic insert 14 on an outer surface of a component 1, 2 of a circuit breaker 100. The shield and the insert comprise holes or through-holes 17 for the insertion of fixing elements such as bolts or screws.

(18) The two metallic inserts 14 are included in the casting process of the main body 3 so that they are partially integrated in the main body.

(19) If a metallic insert 14 and its respective shield 15 are two separate elements, the shield and the insert are assembled together, for example bolted together, and the shield is then assembled on the outer surface of its respective component.

(20) In a variant illustrated in FIG. 6, the insert and its respective shield can also be integrated into a single piece 16. An advantage of an integrated insert is that the insulating support assembly can be assembled on the outer surface of the component from the outer side of the component that it is intended to be joined to and support.

(21) The metallic shields 15 are used to fix the end of the inserts 14 on a component of a circuit breaker by means of fixing elements (such as bolts or screws), but they also serve as shields for the heads of the fixing elements against fuel peaks. Indeed, the fixing elements are inserted into holes 17 provided in the shields, so that the heads of the fixing elements are recessed in the shields and do not protrude from them. The fixing elements are thus shielded inside the shield body and the resulting electric field intensity is reduced. The preferred shape for the head of the fixing element is cylindrical (socket head type), which allows it to be recessed in a round countersunk hole.

(22) The metallic shields are configured to be affixed to the outer surface of the component on which it is to be fixed. Since the components have generally a tubular form, the shields will thus usually have a C-shaped profile. The profiles of two shields (for example C-shaped profiles) of a same strut can be oriented parallel to each other or differently, if necessary, depending on the orientation of the two components to be connected, in order to adapt to the profile of the outer surfaces of the components on which they are to be affixed. For example, as illustrated in FIG. 4, the C-shaped profiles of the shields 15 are parallel and the plans containing the C-shaped profiles of the shields are oriented at an angle of 90° with respect to the plane containing the C-shaped profile of the main body of the strut. In another example illustrated in FIG. 5, the C-shaped profile of one of the shields is parallel to the C-shaped profile of the main body and the plans of the C-shaped profiles of this shield and the main body are oriented at an angle of 90° with respect to the plane of the C-shaped profile of the other one of the shields.

(23) As illustrated in FIG. 7, FIG. 8a, FIG. 8b and FIG. 9, the main body 3 of the strut 120 is elongated and curved with a curvature 18 extending from one end of the main body to the other end and there is a metallic insert 14 partially embedded at each end of the main body.

(24) Preferably, the main body of the strut has a C shape. The C shape actually allows for shorter spacing between the two shields 15, and thus between the two components to be joined by the strut, while still keeping a long distance along the insulator surface of the main body. This distance is important in order to avoid surface tracking under a voltage stress when the insulating support assembly is operating in polluted conditions. Indeed, in a circuit breaker, in particular in a circuit breaker which interrupts high-current magnitudes at high operating voltage, the breaking of currents creates decomposition products in the gas that is used for interruption and these form solid compounds that deposit on surfaces inside the circuit breaker, including on the surface of the main body of the strut.

(25) The main body 3 of the strut is made of an electrically insulating material, in particular a casted epoxy resin. Epoxy resin is the material that is most commonly used for solid electrical insulation in switchgear. In particular, it is used in Gas-Insulated Substations and in Metal Enclosed (dead-tank) circuit breakers. The epoxy resin is casted in a mold under a vacuum process in order to avoid voids or cavities in the material.

(26) The main body can have an ovoid or a circular cross section shape. The ovoid shape provides more mechanical strength in the direction in which the cross section is greater.

(27) As illustrated in FIG. 7, FIG. 8a and FIG. 8b, the smallest dimension of the cross section of the main body is preferably greater than the greatest dimension of the cross section of the metallic insert 14. This configuration ensures that triple points are not protruding. As a reminder, triple points are regions where a solid dielectric material, a metal and a gas meet and these regions are very prone to electron emission under voltage. The configuration of the end fitting is such that the triple point is hidden behind the metal piece incorporated into the epoxy.

(28) As illustrated in FIG. 10, the insulating support assemblies according to the invention can also be used to provide mechanical support to a graded capacitor 19 on an interrupter sub-assembly 1 (contact pole) in a high-voltage gas-insulated metal-enclosed circuit breaker. One can note that the configuration illustrated in FIG. 5 is used here to connect the graded capacitor on the contact pole.

(29) A metallic shield 15 can be affixed on the outer surface of a component. Another option is to recess the entire metallic shield into the outer surface of the component. In the embodiment illustrated in FIG. 11, one of the two metallic shields is affixed on the outer surface of the interrupter sub-assembly 1 and the other shield is recessed into the metal housing of the grading capacitor 19.

(30) One can note that one end of the main body 3 faces the radial direction 50 of the interrupter sub-assembly 1 and the other end of the main body 3 faces the radial direction 60 of the grading capacitor 19. Preferably, as illustrated in FIG. 11, the ends of the curved main body 3 have a 90° angle relative to the radial direction of its respective component.

(31) According to another embodiment, the grading capacitor 19 could be replaced with a pre-insertion resistor.

(32) Preferably, the exposed surface of a shield 15 follows the contour of the outer surface of the component on which it is affixed and its perimeter is rounded to reduce the electric field intensity.