This application claims priority under 35 U.S.C. §119 to European patent application No. 10164240.3 filed in Europe on May 28, 2010, the entire content of which is hereby incorporated by reference in its entirety.
The present disclosure relates to a switching chamber insulation arrangement. More particularly, the present disclosure relates to a switching chamber insulation arrangement for a circuit breaker with an improved heat dissipation capability.
Circuit breakers for switching high voltages and/or high currents in general have contact poles of a complex design. The contact poles can be moved relative to one another in order to carry out a connection or disconnection process. Because of the high voltages and/or currents which occur, it is generally necessary to position the two switch contact poles in a defined manner with respect to one another, such that the corresponding contact surfaces can make contact with one another, and can be disconnected, in a predetermined manner. In order to ensure that the two switch contact poles are positioned correctly, a switching chamber insulation arrangement is provided, which positions the two switching contact poles with respect to one another to ensure geometrically predefined opening and closing of the contact surfaces of the switch contact poles with respect to one another. However, a switching chamber insulation arrangement such as this not only has to ensure that the two switch contacts are mechanically robust with respect to one another, but likewise has to have a dielectric strength, which dielectrically withstands the voltages that occur, for example, when the switch contacts are open. For this purpose, substantially closed tube arrangements have been used until now, to which the two switch contact poles are fixed, thus allowing moving parts of the switch contact poles to be moved toward one another in a defined manner. However, tube arrangements such as these result in spatial compartmentalization of the contact surfaces of the switch contact poles. As a result, heat which is developed cannot reliably be dissipated at the contacts of the switch contact poles in certain operating states.
An exemplary embodiment of the present disclosure provides a switching chamber insulation arrangement, which includes a strut arrangement having a plurality of struts. Each strut has a first foot area, a second foot, area and a center area which is located between the first foot area and the second foot area, respectively. The struts are arranged along a circumference around a longitudinal extent axis of the strut arrangement. The strut arrangement has a first mechanical coupling area on a side of the first foot areas for coupling to a first pole of a circuit breaker, and a second mechanical coupling area on a side of the second foot areas for coupling to a second pole of a circuit breaker.
Additional refinements, advantages and features of the present disclosure are described in more detail below with reference to exemplary embodiments illustrated in the drawings, in which:
In view of the background discussed above, exemplary embodiments of the present disclosure provide a switching chamber insulation arrangement and a circuit breaker with such a switching chamber insulation arrangement, which allow improved heat dissipation in the area of the switch contact poles.
According to an exemplary embodiment of the present disclosure, a switching chamber insulation arrangement includes a strut arrangement with a plurality of struts, wherein each strut has a first foot area, a second foot area and a center area which is located between the first foot area and the second foot area. The struts are arranged along a circumference around a longitudinal extent axis of the strut arrangement. The strut arrangement has a first mechanical coupling area on the side of the first foot areas for coupling to a first pole of a circuit breaker, and a second mechanical coupling area on the side of the second foot areas for coupling to a second pole of a circuit breaker. In this case, the terms “first pole” and “first contact pole”, as well as “second pole” and “second contact pole” of a circuit breaker in the following description do not mean two poles of different electrical phases, but a first contact part and a second part of a single circuit breaker, in which case the first contact part and the second contact part can be electrically disconnected from one another.
Because of the strut arrangement, the area of contact between the two switch contacts is no longer physically compartmentalized from the remaining volume of the switch, but is connected to the remaining volume of the switch. For example, in the case of gas-insulated circuit breakers, it is possible for a gas exchange to occur in the area of the switch contact poles with the remaining gas volume, thus allowing improved heat dissipation to be achieved in the area of the contact points of the switch contact poles. In this case, nevertheless, the strut arrangement allows adequate positioning and force absorption, thereby still ensuring reliable opening and closing of the contact of the switch contact poles. In this case, appropriate mechanical coupling to corresponding areas of the switch contact poles can be achieved via the mechanical coupling areas of the strut arrangement.
According to an exemplary embodiment of the present disclosure, the struts have an elongated cross section in the center area.
As used herein, an “elongated cross section” means a longitudinal extent substantially in the direction of a circumference at right angles to, that is to say azimuthally with respect to, a longitudinal extent axis of the struts or of the strut arrangement. In this case, inter alia, elongated may be, but is not necessarily, oval, elliptical or kidney-shaped. An elongated cross section makes it possible for the struts to have an adequate bending moment, while, however, having only small dimensions in a direction which is radial with respect to the longitudinal extent axis of the strut arrangement, thus making it possible not only to ensure an adequate separation between the live parts of the switch contact poles but also from an outer housing, while at the same time also allowing the radial dimensions to be kept small.
In the case of an exemplary embodiment as an outdoor switch (AIS), the outer housing can be in the form of an insulator. In the case of exemplary embodiments of gas-insulated switchgear assemblies (GIS) or tank switches (DTB), the outer housing can be metallic or at least metal-encapsulated.
According to an exemplary embodiment of the present disclosure, the respective first foot areas and the respective second foot areas are bent through a distance with respect to the corresponding center areas, in a radial direction of the switching chamber insulation arrangement with respect to the longitudinal extent axis.
As used herein, the term “bent” means that the two center axes, that is to say the center axes of the foot areas and the center axes of the center areas, are shifted with respect to one another. In particular, the center areas may in this case be located further radially outward than the foot areas. This makes it possible to fit the foot areas closer to the switch contact poles, while still ensuring an adequate dielectric separation between the contact surfaces and live parts of the switch contact poles and the center areas. This is particularly relevant when the foot areas of the switching chamber insulation arrangement are covered by fuel-controlling elements. This makes it possible to ensure that a circuit breaker with a corresponding switching chamber insulation arrangement is physically compact.
According to an exemplary embodiment of the present disclosure, the first foot area of a respective strut in the strut arrangement is shifted with respect to the associated second foot area in this strut, such that the struts are inclined with respect to the longitudinal extent axis.
For example, the struts may be shaped in a similar manner to a helical section, in order to ensure an adequate separation from the switch poles. This lengthens the effective length of the struts while maintaining the separation between the two mounting planes, which run at right angles to the longitudinal extent direction of the switching chamber insulation arrangement, and in each of which the first and the second foot areas may be located. This results in a lengthened creepage distance along the surface of the respective strut, as a result of which a strut arrangement such as this has a higher surface discharge resistance than a strut arrangement with struts which run parallel to a longitudinal extent direction.
According to an exemplary embodiment of the present disclosure, the strut arrangement can have at least three struts.
This exemplary arrangement allows the two switch contact poles to be positioned in a stable form with respect to one another, for example, when the at least three struts are substantially at the same distance from one another. For example, bending along the longitudinal extent axis can be substantially suppressed. If the struts are in this case inclined with respect to the longitudinal extent axis, this inclination with all of the struts may run in the same direction, thus allowing a symmetrical, helical strut profile to be achieved.
According to an exemplary embodiment of the present disclosure, the strut arrangement has at least four struts, wherein the struts are inclined alternately in opposite senses with respect to the longitudinal extent direction, thus providing stiffening in the circumferential direction around the longitudinal extent axis.
This configuration makes it possible to avoid twisting shifting of the two switch contact poles with respect to one another, with this torsion being achieved substantially by the struts being inclined alternately in opposite senses. The extent of the inclination is in this case governed by the required connection stiffness. Bending and therefore geometric deformation of the struts can be avoided, for example, with respect to forces which occur in the longitudinal extent direction, such as during opening or closing, for example.
According to an exemplary embodiment of the present disclosure, a field control electrode can, in each case, be embedded in the first foot areas and in the second foot areas, with a force absorption apparatus being arranged within the field control electrode.
A force absorption apparatus such as this may, for example, be a thread or a bolt, or else a bayonet connection or a clamping connection. The field control electrode may in this case result in a geometry creating an optimized fuel to the outside, thus making it possible to keep fuel peaks substantially below a critical range. In particular, a metal part with an optimized-field external contour can be provided in the foot areas, and, for example, the force absorption apparatus may be located in its interior, in the form of a thread or some other attachment, such that the force absorption apparatus and the field control electrode are formed integrally.
In this case, the elements of the field control electrode may be composed both of metal and of a material which is at a different potential, for example a plastic to which a potential-carrying additive is added, such as carbon or graphite.
According to an exemplary embodiment of the present disclosure, the first foot areas of the struts are each formed integrally with a first supporting ring, and the second foot areas are each formed integrally with a second supporting ring.
In this case, the supporting rings may run along a circumference which corresponds substantially to the external dimensions of the switch contact poles. This arrangement makes it possible to provide a substantially integral switching chamber insulation arrangement, which can easily be attached to the corresponding switch contact poles without any need to separately align the individual struts with respect to one another. However, the strut arrangement at the same time ensures an appropriate heat dissipation and a gas exchange in a gas-insulated circuit breaker. The bend may in this case be provided both in the area of the struts, that is to say between the foot area and the center part, and in the area of the supporting rings.
According to an exemplary embodiment of the present disclosure, the strut arrangement has a polymer resin, and has a metal-oxide-filled polymer resin in at least one section of an electrical isolating gap.
Polymer resins ensure reliable dielectric strength with mechanical robustness at the same time. An appropriate metal-oxide filling may in this case increase the mechanical robustness, while representing an improved thermal characteristic. By way of example, but not exclusively, an epoxy resin, a polyurethane resin or a phenol resin may be used as polymer resins. In this case, by way of example, aluminum oxide (Al2O3) may therefore be used as a metal oxide. Furthermore, titanium dioxide or magnesium oxide may also be used. One suitable combination may include, for example, an aluminum-oxide-filled epoxy resin, in which case aluminum oxide is resistant to a certain extent to SF6 and SF4 which occur, for example, in gas-insulated circuit breakers. The strut arrangement may in this case have a homogeneous structure, for example, in the form of a homogeneous encapsulation compound or else may be machined from a homogeneous material. In this case, there would be no need for longitudinal structures such as fiber inserts, particularly if these lead to the expectation of a discharge or partial-discharge problem.
According to an exemplary embodiment of the present disclosure, the center area of at least one strut has a shell which is located radially outside the respective strut, and a filling which is located radially within the respective strut.
In this case, the externally located shell may completely surround the respective strut on the outside, or else may be merely in the form of a half-shell. For example, particularly when using materials which are appropriate and resistant to a tension, a shell can absorb corresponding tensile forces, while an internally located filling can absorb compression forces. Furthermore, a shell can also represent mechanical protection for the internally located filling. This makes it possible to provide a strut arrangement which is particularly resistant to tension and compression force, that is to say it is also resistant to bending, for a switching chamber insulation arrangement.
According to an exemplary embodiment of the present disclosure, the circumference is circular, and/or the switching chamber insulation arrangement can be installed in a single-phase-encapsulated circuit breaker.
In this case, a circular circumference makes it easier to assemble the switching chamber insulation arrangement or the circuit breaker, since there is no need for corresponding radial alignment.
According to an exemplary embodiment of the present disclosure, at least a part of the strut arrangement is coated, for example, with a diffusion barrier.
By way of example, a diffusion barrier such as this may be a titanium dioxide coating or an epoxy resin coating. This makes it possible to prevent aggressive decomposition products, which can occur because of the arc effect in a gas-insulated circuit breaker, from attacking or even destroying the structure of the strut arrangement or of the switching chamber insulation arrangement.
However, instead of having a homogeneous material structure, the center part of the struts may also have a load-bearing core insert, which provides robustness, for example a composite tube, a composite strip or a rod, in which case the filling and/or the strut can be cast around the corresponding tube, the strip or the rod. For instance, the center part of the strut may also have a fiber reinforcing insert, such as in a form that there is no need to be concerned about discharge or partial-discharge processes.
According to an exemplary embodiment of the present disclosure, a circuit breaker is provided having a switching chamber insulation arrangement according to the disclosure, a first switch contact pole and a second switch contact pole. The circuit breaker is a single-phase-encapsulated circuit breaker. The switching chamber insulation arrangement and the first and second switch contact poles cam be connected to one another such that the first and second switch contact poles are aligned and fixed in a defined manner with respect to one another.
According to an exemplary embodiment of the present disclosure, the circuit breaker includes a first field control cover which is arranged at a rated current contact junction (nominal contact). The first field control cover is connected, carrying potential, to the first switch contact pole and/or to the second switch contact pole. The first mechanical coupling area is mechanically connected to the first switch contact pole at the first switch contact pole and/or the second switch contact pole, under the first field control cover.
This configuration allows the attachment elements, which are critical for an electrical field, to be covered by a field control cover such that, essentially, no critical fuel peaks may be expected.
It should be noted that the exemplary embodiments of the present disclosure described in the following text relate equally to the switching chamber insulation arrangement and to the circuit breaker. The individual features may, of course, also be combined with one another, thus in some cases allowing advantageous effects to be achieved, which go beyond the sum of the individual effects. These and other aspects of the present disclosure will be explained and described by reference to the exemplary embodiments described below.
As can be seen from the cross sections I-I and II-II, a circular cross section can be chosen, by way of example, in a foot area 11, by way of example, while an elongated cross section, for example an oval or kidney-shaped cross section, can be chosen in a center area 12. In this case, the round cross section is good for attachment, while the elongated cross section in the center area allows a space-optimized strut arrangement in this center area.
It should be noted that the term “comprising” does not exclude further elements, and the term “one” does not exclude “a” plurality of elements. The reference symbols used serve only to assist understanding and should in no way be considered as being restrictive, with the scope of protection of the disclosure being reflected by the claims.
It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.
Number | Date | Country | Kind |
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10164240.3 | May 2010 | EP | regional |