Dielectric shielding heat sink

Abstract

The present invention relates to a dielectric shielding heat sink (10), the dielectric shielding heat sink comprising: - a body (20); wherein the body is configured to be mounted around a movable contact (30) of a circuit breaker and around a part (40) of a copper contact (50) connected to the movable contact; wherein the body is configured to directly contact at least a portion of the part of the copper contact connected to the movable contact.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a dielectric shielding heat sink, to a circuit breaker and a dielectric shielding heat sink, and to a medium or high voltage switchgear.BACKGROUND OF THE INVENTION

[0002] GB2318455A describes that heat sinks are placed on the contact stems of a vacuum interrupter so as to extend radially outward therefrom between the vacuum bottle and junctions with the terminal conductors to lower the temperature of these junctions. It is described that the heat sinks are formed by a stack of thin laminations having central openings with inwardly directed tabs which bite into and secure the laminations to the stems. Tt is described that the laminations have aligned slots forming axial passages for cooling air, and that the slots may be enclosed to eliminate sharp peripheral edges to reduce the potential for flash over. It is described that the slots are not formed by removing material but by bending it out of the plane of the lamination to maximize heat radiating surface area and to generate turbulent cooling air flow for increased cooling efficiency. It is described that an axially extending peripheral lip can provide axial spacing between laminations.

[0003] EP1326262A1 describes that cooling fins of the pole head and / or pole carrier are separated by 6-13 mm, and their length is 150-250 mm in the gas flow direction.

[0004] EP3595105A1 relates to a heat sink for a high voltage switchgear. It is described that the heat sink comprises a body, and the body is centred around a central axis that extends in an axial direction from a first outer surface to a second outer surface. It is described that at least one third outer surface of the body extends from the first outer surface to the second outer surface. It is described that at least one air channel extends through the body from the first outer surface to the second outer surface, and the at least one air channel is surrounded by the at least one third outer surface.

[0005] DE102006041377B3 describes that the armature has a connecting unit made of a material with high electrical conductivity for connecting a fixed contact with a bus bar under the formation of a current path. It is described that a cooling body is made of a material with high thermal conductivity and thermally arranged on the connecting unit. It is described that the cooling body encloses the connecting unit in a form-fit manner. It is described that the cooling body has a fastening unit for fastening of the armature at a circuit breaker. It is described that the connecting unit has two side pieces with two connection surfaces for connecting the bus bar and the fixed contact.

[0006] DE102017217167A1 relates to a pole head for suppressing bouncing movements in switching contacts of a vacuum interrupter by a pole head and on a switch pole with such a pole head. It is described that the pole head further has a bouncing element which is arranged and fastened opposite the fixed contact receptacle in such a way that the bouncing element can absorb and dampen a bouncing energy which acts axially on the fixed contact receptacle.

[0007] Medium or high voltage switch gears have one or more circuit breakers, such as vacuum interrupters. Many bold parts of such circuit breakers use a flexible copper connection to the movable contact of the vacuum interrupter. The flexible copper connection is mounted around the movable contact at one end and at the other end is generally held in a rigid position. The flexibility is provided via a flexible copper contact being in the form of a copper strip or laminate. This then means that the flexible copper contact has sharp edges, or at least edges with small radius is of curvature. From a dielectric point of view, this then is problematic and can lead to electrical breakdown issues.

[0008] Furthermore, this area is one of the hottest areas of the pole part, where for high current applications this area can become very hard due to Joule heating. However, normally heatsinks again have relatively sharp edges with respect to ribs, which again are problematic from a dielectric point of view.

[0009] There is a need to address these issues.SUMMARY OF THE INVENTION

[0010] Therefore, it would be advantageous to have a technology that addresses both the dielectric issues associated with flexible copper connections to the movable contact of a circuit breaker and the heating issues associated with Joule heating of the flexible copper connections.

[0011] The object of the present invention is solved with the subject matter of the independent claim, wherein further embodiments are incorporated in the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Exemplary embodiments will be described in the following with reference to the following drawings: Fig. 1 shows an example of a dielectric shielding heat sink mounted to a movable contact of a circuit breaker; and Fig. 2 shows an isometric view of an example of a dielectric shielding heat sink mounted to a movable contact of a circuit breaker. DETAILED DESCRIPTION OF EMBODIMENTS

[0013] Figs. 1-2 relate to a dielectric shielding heat sink, to a circuit breaker with a dielectric shielding heat sink, and to a medium or high voltage switchgear.

[0014] The circuit breaker has mounted to it a dielectric shielding heat sink 10. The dielectric heat sink comprises a body 20. The body of the the dielectric shielding heat sink is mounted around a movable contact 30 of the circuit breaker and around a part 40 of a copper contact 50 connected to the movable contact. The body of the dielectric shielding heat sink directly contacts at least a portion of the part of the copper contact connected to the movable contact.

[0015] This direct contact relates to direct thermal and electrical contact, and clearly there can be an intermediate electrical / thermal medium between the body and the copper connection, such as an intermediate sheet or gel.

[0016] The dielectric shielding heat sink is made from an electrically conductive material.

[0017] In an example, the electrically conductive material is aluminium.

[0018] In an example, the electrically conductive material is copper.

[0019] In an example, the circuit breaker is a vacuum interrupter.

[0020] The body surrounds the at least a portion of the part of the copper contact connected to the movable contact.

[0021] The body of the the dielectric shielding heat sink forms a dielectrically closed enclosure.

[0022] The body of the the dielectric shielding heat sink forms a dielectrically closed enclosure with respect to the at least a portion of the part of the copper contact connected to the movable contact.

[0023] The body forms a dielectrically closed enclosure with respect to a part of the movable contact to which is connected the part of the copper contact connected.

[0024] The body of the the dielectric shielding heat sink forms a closed enclosure with respect to at least a portion of the part of the copper contact connected to the movable contact. With respect to the closed enclosure there is no direct air path or vacuum path from the at least a portion of the part of the copper contact connected to the movable contact to a region outside of the body.

[0025] The body forms a closed enclosure with respect to a part of the movable contact to which is connected the part of the copper contact connected. With respect to the closed enclosure there is no direct air path or vacuum path from the part of the movable contact to which is connected the part of the copper contact connected to a region outside of the body.

[0026] The body of the dielectric shielding heat sink comprises a central conduit 60 that allows a stem 70 of movable contact to protrude out of the body.

[0027] The body comprises one or more holes or recesses 80 in an outer surface of the body.

[0028] The one or more holes or recesses do not connect the outer surface of the body to an inner surface of the body.

[0029] In an example, one or more of the holes or recesses extend from one part of the outer surface of the body to another part of the outer surface of the body.

[0030] In an example, corners and edges of the body are rounded.

[0031] 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 below that for electrical breakdown.

[0032] In an example, the ribbed surface comprises fins that extend in the axial direction.

[0033] Thus, a medium or high voltage switchgear can comprise at least one dielectric shielding heat sink as described above.

[0034] Thus, a closed heat sink has been designed, such that it can be used as an electric shielding for the sharp edges of copper laminations used as contacts and additionally work as a dielectrically optimised heat sink with large rounded edges and corners at the outside to call down art area of the circuit breaker, such as the pole part. The new heat sink can be retrofitted to existing circuit breakers, or circuit breaker can be manufactured with such a heatsink as part of the overall heatsink embodiment.

[0035] The heatsink, is from a dielectric point of view, closed and it has no open holes that extend from the inside to the outside. The outside of the heat sink has holes for cooling, and the outside has large radius edges and corners, and no sharp edges. The heat sink is then placed around the movable contact of the vacuum interrupter / circuit breaker and around the flexible copper connection, in the form of elimination. It works as a dielectric shielding for the sharp edges of the copper connection, and is in direct contact with the copper connection where it connects to the movable contact, and is used to cool down this area.

Claims

1. A circuit breaker and a dielectric shielding heat sink (10), the dielectric shielding heat sink comprising: - a body (20); wherein the body is mounted around a movable contact (30) of the circuit breaker and around a part (40) of a copper contact (50) connected to the movable contact; wherein the body comprises a central conduit (60), wherein a first part of an inner surface of the central conduit directly contacts and surrounds at least a portion of the part of the copper contact connected to the movable contact and a second part of the inner surface of the central conduit directly contacts the movable contact such that the body forms a dielectrically closed enclosure with respect to the at least a portion of the part of the copper contact connected to the movable contact and with respect to the movable contact, wherein a third part of the inner surface of the central conduit is spaced from at least a part of a stem (70) of the movable contact to allow the stem connected to the movable contact to protrude out of the body, wherein for the dielectrically closed enclosure there is no direct air or isolation-gas path from the at least a portion of the part of the copper contact connected to the movable contact to a region outside of the body and there is no direct air or isolation-gas path from the movable contact to a region outside of the body, wherein no direct air or isolation-gas path means that no open holes extend from the at least a portion of the part of the copper contact connected to the movable contact to a region outside of the body and no open holes extend from the movable contact to a region outside of the body, and wherein the isolation-gas comprises AirPlus or SF6; wherein the body comprises a plurality of holes or recesses (80), wherein one or more holes or recesses of the plurality of holes or recesses are in an outer surface of the body and one or more holes or recesses of the plurality of holes or recesses are in the third part of the inner surface of the central conduit, and wherein none of the plurality of holes or recesses connect the outer surface of the body to the first part of the inner surface of the central conduit and none of the plurality of holes connect the outer surface of the body to the second part of the inner surface of the central conduit; and wherein the dielectric shielding heat sink is made from an electrically conductive material.

2. Circuit breaker and the dielectric shielding heat sink according to claim 1, wherein one or more of the holes or recesses extend from one part of the outer surface of the body to another part of the outer surface of the body.

3. Circuit breaker and the dielectric shielding heat sink according to any of claims 1-2, wherein corners and edges of the body are rounded.

4. Circuit breaker and the dielectric shielding heat sink according to claim 3, wherein 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 below that for electrical breakdown.

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