Heat sinks for high voltage switchgear

Abstract

The invention relates to a heat sink (10) for a high voltage switchgear. The heat sink comprises a body (20). The body is centered around a central axis, the central axis extending in an axial direction from a first outer surface (30) to a second outer surface (40). At least one third outer surface (50) of the body extends from the first outer surface to the second outer surface. At least one air channel (60) extends through the body from the first outer surface to the second outer surface. The at least one air channel is surrounded by the at least one third outer surface.

Description

Technical Field

[0001] The invention relates to a heat sink for a high voltage switchgear and to a medium voltage or high voltage switchgear. Background Art

[0002] Medium voltage and / or high voltage components (e.g. medium voltage or high voltage switchgear) require cooling using an external heat sink made of a conductive material. The heat sink is mounted on the component that needs to be cooled, wherein the body of the heat sink is externally provided with fins, which have rounded edges to reduce the electrical stress at these edges. The fins are usually quite thin, and therefore these edges have a small radius. At small radii, an electric field enhancement occurs, which reduces the dielectric properties. To alleviate this, in order to avoid discharges, an insulating layer is often applied to the stressed areas of the heat sink. This layer, which has a higher discharge voltage than the gas insulation material around the configuration, is used to improve the dielectric properties. However, due to the electric field enhancement at the small radius points of the heat sink, the discharge voltage of the configuration is reduced. Even with a solid insulation layer on these radii, the weak point is the radius, or more precisely the area with the solid insulation end.

[0003] Therefore, there is a need to improve the heat sink used in such situations. Summary of the invention

[0004] It would therefore be advantageous to have improved techniques for providing heat sinks for medium voltage or high voltage switchgear.

[0005] The objects of the invention are solved by the subject-matter of the independent claims, wherein further embodiments are incorporated in the dependent claims.It should be noted that the following described aspects of the invention also apply to a heat sink and a switchgear having at least one heat sink.

[0006] In a first aspect, a heat sink for a high voltage switchgear is provided, the heat sink comprising a body. The body is centered around a central axis extending in an axial direction from a first outer surface of the body to a second outer surface of the body. At least one third outer surface of the body extends from the first outer surface to the second outer surface. At least one air passage extends through the body from the first outer surface to the second outer surface. At least one air passage is surrounded by at least one third outer surface.

[0007] In this way, the heat sink is not only cooled by radiation cooling from the outer surface, but also provides higher cooling by convective heat dissipation through the internal components of the heat sink. This enables improved cooling capacity, thereby taking heat away from critical locations, such as pole parts, and connections and contacts within the switchgear, for example. Therefore, the increase in contact resistance due to the generated heat is mitigated via effective heat dissipation from the new heat sink design with internal cooling capabilities.

[0008] Thus, medium voltage or high voltage components such as switchgear can be cooled by the external heat sink.In an example, the heat sink is made of an electrically conductive material.

[0009] In an example, at least one air channel comprises a ribbed surface.

[0010] In other words, the heat sink has internal ribs to provide higher convective cooling efficiency from inside the heat sink.

[0011] In an example, the ribbed surface extends from the first outer surface to the second outer surface.

[0012] In examples, the ribbed surface comprises fins extending in the axial direction.

[0013] In examples, the at least one air passage comprises an air passage extending downwardly along a central axis of the body.

[0014] In an example, the at least one air channel includes at least one curved air channel.

[0015] In an example, at least one arcuate air passage has a radius of curvature centered along the central axis.

[0016] In an example, the at least one arcuate air channel comprises a plurality of air channels, each of the plurality of air channels having a different radius of curvature centered along the central axis.

[0017] In this way, the manufacture of the heat sink is facilitated and a higher cooling capacity is provided.

[0018] In an example, at least a portion of a junction between the at least one third outer surface and the first outer surface has a convex rounded portion.

[0019] In an example, at least a portion of a junction between the at least one third outer surface and the second outer surface has a convex rounded portion.

[0020] In this way, the heat sink can have a smooth outer geometry with rounded edges at surfaces with large radii. Such smooth surfaces reduce the electric field strength at the heat sink surface and thus improve dielectric properties. This helps because the surface(s) of the heat sink used to dissipate heat are located inside the heat sink, which is open to the surface, thereby facilitating convection cooling, but the internal cooling channels are shielded from the electric field by the outer contour of the heat sink (which may be cylindrical, for example).

[0021] In an example, at least one third outer surface includes a planar portion. The planar portion is configured to be mounted to one or more components of the high voltage switchgear.

[0022] Thus, the heat sink can be easily mounted at appropriate points in a system such as a switchgear, such as a pole part, and all connections and contacts.

[0023] In an example, the at least one third outer surface has a substantially cylindrical shape having a radius of curvature centered along the central axis.

[0024] In an example, the radius of curvature of the substantially cylindrical shape is selected such that in operation the electric field strength at the at least one third outer surface is minimized.

[0025] In an example, the body is made of aluminum.

[0026] In an example, the body is made by hollow extrusion.

[0027] In an example, the at least one third outer surface comprises a ribbed surface.

[0028] In a second aspect, a medium voltage or high voltage switchgear is provided, comprising at least one heat sink according to the first aspect.

[0029] The aspects and examples described above will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Exemplary embodiments will be described hereinafter with reference to the following drawings:

[0031] Figure 1 A schematic representation of an example of a heat sink is shown;

[0032] Figure 2 shows a detailed example of a heat sink; and

[0033] Figure 3 Shows Figure 2 The electric field strength at the cylindrical surface of the heat sink. DETAILED DESCRIPTION

[0034] Figure 1 An example of a heat sink 10 for a high voltage switchgear is shown, wherein optional features are shown in dashed lines. The heat sink 10 includes a body 20. The body is centered around a central axis extending in an axial direction from a first outer surface 30 of the body to a second outer surface 40 of the body. At least one third outer surface 50 of the body extends from the first outer surface to the second outer surface. At least one air passage 60 extends through the body from the first outer surface to the second outer surface. At least one air passage is surrounded by at least one third outer surface.

[0035] According to an example, at least one air channel comprises a ribbed surface.

[0036] According to an example, the ribbed surface extends from the first outer surface to the second outer surface.

[0037] According to an example, the ribbed surface comprises fins extending in the axial direction.

[0038] According to an example, the at least one air passage comprises an air passage extending downwardly along a central axis of the body.

[0039] According to an example, the at least one air channel comprises at least one arcuate air channel.

[0040] According to an example, at least one arcuate air channel has a radius of curvature centered along the central axis.

[0041] According to an example, the at least one arcuate air channel includes a plurality of air channels, wherein each air channel of the plurality of air channels has a different radius of curvature centered along the central axis.

[0042] According to an example, at least a portion of the junction 70 between the at least one third outer surface and the first outer surface has a convex circular portion.

[0043] According to an example, at least a portion of the junction 80 between the at least one third outer surface and the second outer surface has a convex circular portion.

[0044] In an example, the rounded portion has a large radius of curvature. In an example, the radius of curvature is larger than a dimension of the body.

[0045] According to an example, at least one third outer surface comprises a flat portion 90. The flat portion is configured to be mounted to one or more components of the high voltage switchgear.

[0046] In an example, the body at the location of the flat portion has at least one threaded hole extending into the interior of the body. In an example, the at least one threaded hole has at least one central axis perpendicular to the flat portion.

[0047] According to an example, the at least one third outer surface has a substantially cylindrical shape having a radius of curvature centered along the central axis.

[0048] According to an example, a radius of curvature of the substantially cylindrical shape is selected such that in operation the electric field strength at the at least one third outer surface is minimized.

[0049] According to an example, the body is made of aluminum.

[0050] According to an example, the body is produced by hollow extrusion.

[0051] According to an example, the at least one third outer surface comprises a ribbed surface.

[0052] In examples, the ribbed surface comprises fins extending in the axial direction.

[0053] References above to air passages relate to passages that may allow air to flow therethrough, but in some cases gases other than air may be used in the device and the skilled person will appreciate that the passages are suitable for convective cooling flows associated with these other gases than air.

[0054] about Figure 1 One or more of the heat sinks described may be used to cool appropriate components of a medium voltage or high voltage switchgear.

[0055] refer to Figures 2 to 3 Describe in more detail Figure 1 radiator.

[0056] Figure 2 A heat sink with internal fins or ridges or ribs is shown in detail. The heat sink is made of aluminum and has a cylindrical outer shape with rounded edges connecting the cylindrical portion to two flat surfaces. The rounded edges have a larger radius, which reduces the field enhancement at the outer surface of the heat sink compared to other heat sinks with features such as fins with a small radius on the outer surface of the heat sink. The dielectric properties of the heat sink can therefore be improved. In addition, when the distance from the center of the heat sink to the grounded portion of the switching device is fixed, the diameter of the heat sink can be selected for a specific implementation so that the electric field at the outer surface of the heat sink is minimized. This is in Figure 3 is shown in Figure 3 The electric field intensity at the cylindrical surface with an applied voltage of 170 kV and a fixed distance of 225 mm between the central axis of the heat sink and the grounded wall is plotted.

[0057] Continue to refer Figure 2 , the fins for heat dissipation are located inside the cylindrical heat sink, thereby providing sufficient surface for heat dissipation without requiring a small radius at the outer contour of the heat sink where the electrical stresses are highest. In the new design, heat is dissipated due to thermal convection of the gas along the internal fins, wherein radiation cooling and convection cooling are also provided due to radiation emission from the outer surface and air flow on the outer surface. However, by providing internal fins, cooling is enhanced while the dielectric properties are improved. The internal fins also partially shield the electric field and therefore do not lead to a strong enhancement of the electric field. Furthermore, the geometric structure of the heat sink lends itself to manufacturing by hollow extrusion, thereby providing cheap production. In this way, the cost of each heat sink can be reduced compared to a conventional heat sink made of aluminum, for example by pressure casting.

[0058] It should be noted that embodiments of the present invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method type claims, while other embodiments are described with reference to device type claims. However, those skilled in the art will know from the above and following descriptions that, unless otherwise notified, any combination of features related to different subject matters, in addition to any combination of features belonging to one type of subject matter, is also considered to be disclosed by the present application. However, all features can be combined to provide synergistic effects rather than just the simple sum of these features.

[0059] Although the present invention has been illustrated and described in detail in the drawings and the above description, such illustration and description should be considered illustrative or exemplary rather than restrictive. The present invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and realized by those skilled in the art in the process of practicing the present invention through studying the drawings, the present disclosure and the dependent claims.

[0060] 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. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere 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. Any reference signs in the claims should not be construed as limiting the scope.

[0061] Figure 3 The electric field strength at the cylindrical surface is shown for a fixed distance of 225 mm between the center point of the heat sink and the grounded wall and an applied voltage of 170 kV. This calculation is done with Schwaiger's utilization factor.

Claims

1. A heat sink for a high voltage switchgear, the heat sink being configured to cool a medium voltage and / or high voltage part of the high voltage switchgear, the heat sink being made of a conductive material, and the heat sink comprising: Ontology(20); wherein the body is centered about a central axis, the central axis extending in an axial direction from a first outer surface portion of an outer surface of the body to a second outer surface portion of the body; wherein at least one third outer surface portion of the body extends from the first outer surface portion to the second outer surface portion; wherein a plurality of air passages extend through the body from the first outer surface portion to the second outer surface portion and are located within the body, wherein said air passage is surrounded by said at least one third outer surface portion, wherein each of the air channels comprises a respective ribbed surface, wherein a respective rib-shaped surface of each of the air passages extends from the first outer surface portion to the second outer surface portion, wherein each of the plurality of arcuate air passages has a corresponding radius of curvature centered along the central axis, wherein the respective radii of curvature of the plurality of arc-shaped air passages are different, and The plurality of arc-shaped air passages are spaced apart from each other in a radial direction relative to the central axis. 2 . The heat sink of claim 1 , wherein the ribbed surface includes fins extending in the axial direction. 3 . The heat sink of claim 1 , wherein the at least one air passage comprises an air passage extending downwardly along the central axis of the body. 4 . The heat sink according to claim 1 , wherein at the outer surface of the body, at least a portion of a joint between the at least one third outer surface portion and the first outer surface portion has a first convex circular portion.

5. The heat sink according to claim 4, wherein at the outer surface, at least a portion of the joint between the at least one third outer surface portion and the second outer surface portion has a second convex circular portion, wherein the first outer surface portion is on the side of the body opposite to the second outer surface portion, and wherein the at least one third outer surface portion is located between the first convex circular portion and the second convex circular portion. 6 . The heat sink of claim 1 , wherein the at least one third exterior surface portion comprises a planar portion, and wherein the planar portion is configured to be mounted to one or more components of the high voltage switchgear.

7. The heat sink of claim 1, wherein the at least one third outer surface portion comprises a cylindrical shape having a radius of curvature centered along the central axis.

8. The heat sink of claim 7, wherein the radius of curvature of the cylindrical shape minimizes an electric field strength at the at least one third outer surface portion in operation.

9. The heat sink of claim 1, wherein the body is made of aluminum.

10. The heat sink of claim 1 wherein the body is a hollow extrusion.

11. A medium voltage or high voltage switchgear comprising the heat sink according to claim 1.

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