Metal enclosure for electrical switchgear

Abstract

The invention relates to a metal enclosure (100) for an electrical switching device (170), the metal enclosure being configured to be pressurized above atmospheric pressure, the metal enclosure comprising: metal walls (102, 104, 106, 108, 110, 111) sealing a volume (124) for accommodating the electrical switching device, the metal walls comprising a first metal wall (102) arranged opposite a second metal wall (110), wherein the second metal wall comprises an elongate recess (112) located on an inner surface (140) of the second metal wall, and a metal beam (120) arranged and attached in the elongate recess, the metal beam configured to reinforce structural integrity of the second metal wall, a plane of an inner surface (140) of the second metal wall is substantially aligned with a plane of a surface (142) of the metal beam facing the interior of the metal enclosure.

Description

Technical Field

[0001] The present invention relates to a metal enclosure for an electrical switching device. Background Art

[0002] The metal enclosure for gas insulated switchgear encloses the switchgear in a pressurized environment. The gas is selected to provide electrical insulation within the metal enclosure, and a typical gas is SF6, although other gases are also suitable, such as dry air, N2, CO2, or a mixture of two or three of N2, O2, CO2.

[0003] The dielectric resistance of the gas is proportional to the pressure within the metal capsule. Therefore, it is advantageous to increase the pressure of the gas within the metal capsule. However, this means that the metal capsule wall must be able to withstand the forces generated by the increased pressure.

[0004] It is therefore desirable to increase the ability of metal enclosures for gas insulated switchgear to withstand higher pressures, as discussed in more detail below. Summary of the invention

[0005] In view of the above and other shortcomings of the prior art, an object of the present invention is to provide a metal capsule that at least partially alleviates the deficiencies of the prior art.

[0006] According to a first aspect of the present invention, a metal enclosure for an electrical switching device is provided, the metal enclosure being configured to be pressurized to a pressure higher than atmospheric pressure, the metal enclosure comprising: a metal wall sealing a volume for accommodating the electrical switching device, the metal wall comprising a first metal wall arranged opposite to a second metal wall, wherein the second metal wall comprises an elongated recess on an inner surface of the second metal wall; and a metal beam arranged and attached in the elongated recess, the metal beam being configured to reinforce the structural integrity of the second metal wall, the plane of the inner surface of the second metal wall being substantially aligned with the plane of a surface of the metal beam facing the interior of the metal enclosure.

[0007] The present invention is based at least in part on the realization of attaching metal beams in elongated recesses on the inwardly facing side of a metal enclosure. The metal beams can be used to strengthen the structural integrity of the metal enclosure, thereby improving its ability to withstand the gas pressure within the metal enclosure. In particular, the metal beams can be used to increase the gas pressure within the metal enclosure.

[0008] Furthermore, the dielectric image inside the metal enclosure benefits from having a relatively planar surface facing the electrical switching device. Thus, the metal beam is placed in the recess, which is configured so that the inner surface of the inner wall or the second wall substantially coincides with the same position as the surface of the metal beam facing the interior of the metal enclosure. Thus, a relatively planar internal structure of the metal enclosure is advantageously obtained, while improving the ability to withstand higher pressures.

[0009] Withstanding higher pressures is particularly important when moving to dry air, N2, CO2, or a mixture of any two or three of these as dielectric gases. These gases require higher pressures to provide adequate insulation without increasing the distances between switchgear phases and components compared to less environmentally friendly alternatives such as SF6. Despite the move to different gases, it is desirable to maintain the size of the metal enclosure, or at least not increase it.

[0010] Generally speaking, in electrification and gas-insulated switchgear (GIS), if the gas pressure in a metal enclosure exceeds 1.5 bar absolute, the enclosure can be called a high-voltage enclosure according to known standards. If so, it must pass the relevant pressure routine tests, which makes traditional enclosures bulky and quite expensive. Therefore, the filling pressure of a medium voltage (MV)-GIS as discussed herein is traditionally <1.5 bar absolute, for example in the range of 1.0-1.5 bar absolute. Advantageously, the metal enclosure disclosed herein is suitable for a filling pressure of 1.0-4.0 bar absolute, preferably 1.5-3.0 bar absolute. In other words, the pressure is increased compared to the traditional 1.0-1.5 bar absolute pressure range without the need for bulky and oversized enclosure walls.

[0011] According to one embodiment, the width of the metal beam can substantially fill the width of the notch. That is, there is almost no gap between the side of the notch and the side of the metal beam. This provides a flatter internal structure for the metal enclosure.

[0012] According to one embodiment, the thickness of the metal beam may substantially correspond to the depth of the recess. Thus, the metal beam is flush with the inner surface of the second wall to provide a flatter metal enclosure inner structure and improve the dielectric image.

[0013] According to one embodiment, the metal beam and the recess may together form a channel, wherein the metal beam may include a cutout at each end portion to allow gas inflow and gas outflow. The cutout at the end of the metal beam may provide for communication to an adjacent wall that is not sealed from the hollow interior space of the beam. This allows the metal beam to act as a duct or channel for gas circulation and a heat sink for the switchgear within the metal enclosure.

[0014] According to one embodiment, the metal beam may be welded to the recess. Welding provides a strong mechanical connection.

[0015] According to one embodiment, the second wall may include a plurality of metal plates that are attached together to form a complete second metal wall, wherein the joints between the metal plates may be located at and along the elongated recesses. That is, the second wall may be divided into several parts that are welded together with the joints at the recesses. A divided second wall is not necessary, but may simplify the assembly of the metal enclosure.

[0016] According to one embodiment, the capsule may include a third metal wall connected to the first metal wall and the second metal wall, the third metal wall including a planar inner surface. The third metal wall may be a top plate of the metal capsule. The planar inner surface provides improved dielectric properties inside the metal capsule.

[0017] According to one embodiment, the third metal wall may include corrugations and a set of elongated metal elements attached to the inner surface of the third metal wall in the valley of the corrugations facing the interior of the metal capsule to provide a planar inner surface. The corrugations increase the strength of the metal capsule, while the elongated metal elements provide a planar inner surface.

[0018] According to one embodiment, the metal enclosure may include a set of elongated metal elements attached to the metal beams of the first metal wall and the second metal wall, the elongated metal elements extending through the interior space of the metal enclosure. The elongated metal elements help to withstand higher pressures by providing a mechanical connection between the first wall and the second wall. Thus, when pressure tries to bulge the first wall and the second wall, the elongated metal elements provide mechanical resistance.

[0019] According to one embodiment, the metal enclosure may include a set of elongated metal reinforcements attached to the back side of the first metal wall outside the metal enclosure, wherein the elongated metal elements are attached to the elongated metal reinforcements. The reinforcements, which may be elongated metal plates, may be used to distribute the forces on the back side of the first metal wall, which further increases the pressure resistance of the metal enclosure. Using more than one metal reinforcement advantageously distributes the forces over a larger area, thus further increasing the pressure resistance.

[0020] The walls of the metal enclosure may be made of steel. Steel provides a strong material that increases the ability of the metal enclosure to withstand internal pressure.

[0021] The back side is generally the side of the wall facing outwards. That is, the back side faces the outside of the metal capsule opposite to the volume enclosed by the capsule.

[0022] According to one embodiment, the elongated metal element may be attached to the first metal wall by welding and to the metal beam by bolting.

[0023] According to one embodiment, the elongated metal element may be a metal rod or a metal bar.

[0024] According to one embodiment, the rods or bars may comprise longitudinal slots at their end portions, wherein the elongated metal reinforcements fit and are attached in the slots. In this way, the connection strength between the rod and the reinforcement is increased. The metal reinforcements may be welded to the rod in the slots. The longitudinal slots are slots along the longitudinal axis of the rod.

[0025] Alternatively, the metal reinforcement may include a slot in which the rod fits and is attached.

[0026] Likewise, the rods can be welded directly to the wall without penetrating the wall, or the rods can be welded to a middle section which can then be bolted or welded to the wall.

[0027] According to one embodiment, the wall of the metal enclosure may be made of steel. Steel is a strong material that improves the ability of the metal enclosure to withstand internal pressure.

[0028] In a second aspect of the invention, there is provided a gas insulated switchgear comprising: a set of electrical switches; and a metal enclosure according to any one of the embodiments disclosed herein.

[0029] Further effects and features of the second aspect of the present invention are largely similar to those described above in conjunction with the first aspect of the present invention.

[0030] Further features and advantages of the present invention will become apparent when studying the appended claims and the following description.Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] These and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings showing exemplary embodiments of the present invention, in which:

[0032] Figure 1 is a perspective view of the front side of a metal capsule according to an embodiment of the present invention;

[0033] Figure 2 is a perspective view of the back side of a metal capsule according to an embodiment of the present invention;

[0034] Figure 3 is an exploded view of a metal capsule according to an embodiment of the present invention;

[0035] Figure 4 is a close-up cross-sectional view of a metal rod connected to an elongated reinforcement member according to an embodiment of the present invention;

[0036] Figure 5 is a metal enclosure with a top plate removed according to an embodiment of the present invention;

[0037] Figure 6 shows the interior of a second metal wall according to an embodiment of the present invention, wherein the metal beams in their recesses form channels; and

[0038] Figure 7 A bottom view of a third wall according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0039] In this detailed description, various embodiments of the present invention are described with reference to specific embodiments. When describing the embodiments, for the sake of clarity, specific terms are used. However, the present invention is not intended to be limited to the specific terms so selected. Although specific exemplary embodiments are discussed, it should be understood that this is done only for the purpose of illustration. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the scope of the present invention.

[0040] Figure 1 A front view of a metal enclosure 100 for an electrical switching apparatus is shown, Figure 2 A rear view is shown. The metal capsule 100 is configured to be pressurized above atmospheric pressure.

[0041] The metal enclosure 100 includes metal walls 102 , 104 , 106 , 108 , 110 , 111 that seal a volume for housing an electrical switching apparatus.

[0042] The metal wall includes a first metal wall 102 arranged opposite to a second metal wall 110. Figure 2 As more clearly shown in FIG. 1 , the second metal wall 110 comprises an elongated notch 112 on the inner surface of the second metal wall 110. Preferably, the walls 102, 104, 106, 108, 110, 111 of the metal enclosure are made of steel.

[0043] In addition, the third wall 108 provided as a metal plate on the top side of the metal enclosure 100 is connected to the first metal wall 102 and the second metal wall 110 by, for example, welding. The third metal wall 108 includes corrugations 114.

[0044] The elongated metal reinforcements 116 are attached to an outer side 118 of the first metal wall 102. A set of the elongated metal reinforcements 118 attached to the first metal wall 102 are substantially parallel to each other.

[0045] Figure 3 is an exploded view of a metal capsule according to an embodiment of the present invention.

[0046] The metal beam 120 is arranged and attached in the elongated recess 112. The metal beam is configured to strengthen the structural integrity of the second metal wall 110. In other words, through the beam 120, the second metal wall 110 can withstand a higher outward pressure from the gas inside the metal enclosure. In addition, the beam 120 is arranged in the recess 112 so that the structure inside the metal enclosure 100 is substantially planar, thereby improving the dielectric image of the switch inside the metal enclosure 100. That is, there are no or reduced sharp edges or corners inside the metal enclosure 100.

[0047] Furthermore, a set of elongated metal elements 122 are attached to the first metal wall 102 and to the metal beams 120 of the second metal wall 110. The elongated metal elements provided as rods or bars extend through the interior space 124 of the metal enclosure 100. The rods or bars 122 are preferably attached to the elongated metal reinforcement 116, see e.g. Figure 1 The reinforcement 116 is attached to the back side 118 of the first metal wall 102 outside the metal enclosure. The elongated metal element 122 is attached to the first metal wall 102 by welding or bolting and to the metal beam 120 by bolting with bolts 130 or by welding.

[0048] Preferably, the rod 122 is welded to the inside of the first wall 102 without penetrating the wall 102 .

[0049] However, in one possible embodiment and as in Figure 4 As better seen in FIG. 1 , the rod 122 or bar includes a longitudinal slot 132 at its end portion 134. The elongated metal reinforcement 116 fits and is attached in the slot 132. Alternatively, the metal reinforcement 116 may include a slot in which the rod 122 fits and is attached.

[0050] In this example, the rod 122 is passed through the through hole 136 in the first metal wall 102 and welded to the first metal wall 102. In addition, the metal reinforcement 116 is also welded to the first metal wall 102 along the contact interface between the metal reinforcement 116 and the back surface 118 of the first metal wall 102.

[0051] To improve the connection between the rods 122 and the reinforcements 116, the rods 122 may include longitudinal slots 132 at their end portions 134, which extend away from the back surface 118 of the first metal wall 102 to the exterior of the metal enclosure 100. The slots 132 are along respective longitudinal axes 138 of the rods 116a-d. The metal reinforcements 116 may be arranged in the slots 132, in which the metal reinforcements 116 are welded to be fixed to the respective rods 122.

[0052] The rod 122 can be welded to one metal reinforcement 116 on the first metal wall 102. The metal reinforcement 116 fits into a slot 132 at the end 132 of the rod 122. The other rods are welded to another metal reinforcement that fits into the slot of the other rod. Alternatively, the metal reinforcement 116 can include a slot in which the rod 122 fits and is attached.

[0053] Welding is performed on both sides of the slot 132 (eg, the two halves of the rod) along the interface of the metal reinforcement 116 and the slot 132 in the rod 120. The slot can be formed in the center of the rod so that the slot divides the end portion 134 into two halves.

[0054] The bottom plate 111 preferably includes corrugations 114 .

[0055] Figure 5 The metal enclosure 100 is shown with the top plate 108 removed. As shown in this enlarged view, the metal beam is located within the recess 112 in the second metal wall 110. In particular, the inner surface 140 of the second metal wall 110 is substantially aligned with the plane of the surface 142 of the metal beam 120 facing the interior of the metal enclosure 100. In this way, the internal structure of the metal enclosure 100 at the second metal wall 110 is substantially planar. Preferably, the entire inner surface 140 combined with the surface 142 of the metal beam 120 is substantially planar.

[0056] Preferably, the width W of the metal beam 120 measured perpendicular to the longitudinal axis 144 of the metal beam 120 fills the width of the recess 112. Therefore, the metal beam 120 spans the entire width of the recess 112, so that there is no gap or only a very small gap between the side 146 of the metal beam 120 and the corresponding side of the recess 112.

[0057] Preferably, the thickness T of the metal beam 120 substantially corresponds to the depth of the notch 112. That is, the surface 142 of the metal beam 120 facing the interior of the metal enclosure 100 is flush with the inner surface 140 of the metal enclosure so that they together form a plane. Note that a slight discontinuity may occur at the intersection of the metal beam 120 and the inner surface 140.

[0058] The metal beam 120 has a hollow interior space 150 that allows access to the bolts 130 secured to the rods 122 through the holes of the beam 120 before the metal beam 120 is attached in the recess 112. In addition, the beam can be formed from a bent sheet material into a strong U-shape. Overall, the recess provides a method of anchoring the reinforced metal beam 120 without damaging the planar interior surface 140 of the metal enclosure 100. The metal beam 120 can be welded to the recess 112.

[0059] Back to Figure 3 In this embodiment, the second metal wall 110 (eg, rear wall) includes a plurality of metal plates 110a-c that are attached to form the complete second metal wall 110. The joints 152 between the metal plates 110a-c (at Figure 5 144). The rear plates 110a-c may be welded together with the metal beam 120 by vertical welding. To this end, the rear plates 110a-c require holes or other shapes for welding. However, laser welding is contemplated to weld through the rear plates 110a-c.

[0060] Figure 6The interior of the second metal wall 110 is shown, wherein the metal beam 120 is located in its recess 112. The interior space between the metal beam 120 and the recess 112 together forms a channel 150. The metal beam 120 includes a cutout 155 located at each end portion 156a, 156b to allow gas to flow in through an inlet 158 ​​and out through an outlet 160. When the top plate 108 is attached, the cutout 155 (generally U-shaped, polygonal or circular) at the first end portion 156a provides an opening 158 into the channel 150. In a similar manner, the cutout 155 at the second end portion 156b at the bottom plate 111 provides an opening 160 to the channel 150 at the bottom plate 111. The channel provides a chimney effect for air circulation and heat dissipation inside the metal enclosure 100. The cutout is formed in an inwardly facing portion 143 of the metal beam 120, which faces the metal enclosure and includes a planar surface 142.

[0061] Figure 7 A bottom view of the third wall 108 or top plate 108 is shown. The top plate 108, when installed, is connected to both the first metal wall 102 and the second metal wall 110. The top plate 108 is preferably also connected to the side metal walls 106 and 104.

[0062] The third metal wall 108 includes a planar inner surface 162 that improves dielectric properties within the metal enclosure 100 .

[0063] In this embodiment, the third metal wall 108 includes corrugations 114. To obtain a planar surface, a set of elongated metal elements 164 (e.g., plates) are attached to the inner surface of the third metal wall facing the interior of the metal enclosure 100 in the valleys 166 when viewed from the inside of the corrugations to provide a planar inner surface. That is, the plates 164 are placed in the area of ​​the valleys 166 to flatten the valleys 166 inside the top plate 108 so that the entire inner surface 162 is planar.

[0064] In an alternative embodiment, the top plate 108 is flat and has no corrugations. This provides a flat inner surface. In this case, an external metal reinforcement bar can be attached to the outer surface of the top plate 108 to strengthen the top plate.

[0065] See also Figure 1, a gas insulated switchgear 10 is also provided, which includes a set of electrical switches 170 and a metal enclosure 100 pressurized by gas. These switches can be suitable for operation at 10-52kV, preferably 12 / 24 / 36, 40.5kV, and can have a modular construction related to the combination of switches that can be assembled in sequence in the metal gas enclosure 100. These switches can be, for example, CC, CCV, CCF, CCCC, etc., where C: cable switch module, De: direct cable connection with grounding module, D: cable direct connection module, F: switch-fuse disconnector module, V: vacuum circuit-breaker module. Preferably, the gas in the metal enclosure is dry air, N2, CO2, or a mixture of any two or three of N2, O2, CO2.

[0066] Although three plates 110a-c are shown, the number of plates depends on the specific implementation adopted, and thus may be more or less than three. Likewise, the number of rods (four here) or the number of metal beams (two shown here) are shown only as examples and may vary depending on the implementation.

[0067] Even though the invention has been described above with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art.

[0068] Furthermore, variations of the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A metal enclosure (100) for an electrical switching device (170), the metal enclosure being configured to be pressurized to a pressure above atmospheric pressure, the metal enclosure comprising: A metal wall (102, 104, 106, 108, 110, 111) for sealing a volume (124) for accommodating the electrical switching device, the metal wall comprising a first metal wall (102) disposed opposite a second metal wall (110), wherein the second metal wall comprises an elongated recess (112) located on an inner surface (140) of the second metal wall, and A metal beam (120) is arranged and attached in the elongated recess, the metal beam being configured to reinforce the structural integrity of the second metal wall, the plane of the inner surface (140) of the second metal wall being substantially aligned with the plane of the surface (142) of the metal beam facing the interior of the metal enclosure.

2. The metal capsule according to claim 1, wherein: The width (W) of the metal beam substantially fills the width of the recess.

3. The metal capsule according to any one of claims 1 and 2, wherein: The thickness (T) of the metal beam substantially corresponds to the depth of the recess.

4. A metal capsule according to any one of the preceding claims, wherein: The metal beam and the recess together form a channel (150), wherein the metal beam includes a cutout (155) at each end portion (156a, 156b) to allow gas inflow (158) and gas outflow (160).

5. A metal capsule according to any one of the preceding claims, wherein: The metal beam is welded to the recess.

6. A metal capsule according to any one of the preceding claims, wherein: The second wall comprises a plurality of metal plates (110a-c) attached to form a complete second metal wall, wherein joints between the metal plates are located at and along the elongated recesses.

7. The metal enclosure of any one of the preceding claims, comprising a third metal wall connected to both the first metal wall and the second metal wall, the third metal wall comprising a planar inner surface (162).

8. The metal capsule according to claim 7 comprises corrugations (114) and a set of slender metal elements (164), which are attached to the inner surface of the third metal wall facing the interior of the metal capsule in the valleys (166) of the corrugations to provide a planar inner surface.

9. The metal enclosure according to any of the preceding claims, comprising a set of elongated metal elements (122) attached to the first metal wall and to the metal beams of the second metal wall, the elongated metal elements passing through the inner space of the metal enclosure.

10. The metal enclosure of claim 9, comprising a set of elongated metal reinforcements (116) attached to the back side of the first metal wall outside the metal enclosure, wherein the elongated metal elements are attached to the elongated metal reinforcements.

11. The metal capsule according to claim 10, wherein: The elongated metal element is attached to the first metal wall by welding or bolting and to the metal beam by bolting or welding.

12. The metal capsule according to any one of claims 10 and 11, wherein: The elongated metal element is a metal rod or bar.

13. The metal capsule according to claim 12, wherein: The rod or bar comprises a longitudinal slot (132) at its end portion, wherein the elongated metal reinforcement fits and is attached in the slot, or wherein the metal reinforcement comprises a slot, wherein the rod fits and is attached in the slot.

14. A metal capsule according to any one of the preceding claims, wherein: The walls of the metal enclosure are made of steel.

15. A gas insulated switchgear (10), comprising: a set of electrical switches; and A metal capsule as claimed in any preceding claim which is pressurised with a gas.

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