WO2024165145A1

WO2024165145A1 - Enclosure for a gas-insulated medium-voltage or high-voltage apparatus

Info

Publication number: WO2024165145A1
Application number: PCT/EP2023/052973
Authority: WO
Inventors: Urs Kruesi; Michael GATZSCHE
Original assignee: Hitachi Energy Ltd
Priority date: 2023-02-07
Filing date: 2023-02-07
Publication date: 2024-08-15

Abstract

The invention relates to an enclosure (1) for a gas-insulated medium-voltage or high-voltage apparatus comprising a first enclosure tube (2) and a second enclosure tube (3), both having a longitudinal axis (z), and a connection portion (4) arranged axially between the first enclosure tube (2) and the second enclosure tube (3), whereby the connection portion (4) is configured for providing a gas-tight connection between a first end (20) of the first enclosure tube (2) and a second end (30) of the second enclosure tube (3), whereby the connection portion (4) comprises a bracket (9) surrounding the first end (20) and the second end (30), and whereby a coating (8), a machining (8), grease and/or a contact element (10) is provided between the first enclosure tube (2), the second enclosure tube (3) and/or between the bracket (9).

Description

Enclosure for a gas-insulated medium-voltage or high-voltage apparatus

Technical Field

The invention relates to an enclosure for a gas-insulated medium-voltage or high- voltage apparatus comprising a first enclosure tube and a second enclosure tube, both having a longitudinal axis, and a connection portion axially between the first enclosure tube and the second enclosure tube, whereby the connection portion is configured for providing a gas-tight connection between a first end of the first enclosure tube and a second end of the second enclosure tube. The invention further relates to a method for improving a current flow from a first enclosure tube to a second enclosure tube of an enclosure for a gas-insulated medium-voltage or high- voltage apparatus, comprising the first enclosure tube and the second enclosure tube, both having a longitudinal axis, and a connection portion arranged axially between the first enclosure tube and the second enclosure tube, whereby the connection portion is configured for providing a gas-tight connection between a first end of the first enclosure tube and a second end of the second enclosure tube.

Background Art

WO 2022/017584 A1 describes an enclosure for a gas-insulated medium-voltage or high voltage apparatus. Generally, gas-insulated switchgear and gas-insulated lines are built from several up to many hundreds of components, including a number of busbar tubes connected to each other. Each component has its own housing, which is connected to the adjacent housing by a flange. The connections by flanges must assure mechanical stability, gas-tightness and enclosure current flow. Thus, the flanges are typically pressed onto each other with a high force, which is applied by using several screw or bolt connections distributed around the circumference of the flanges. WO 2022/017584 A1 proposes a connection portion between a first end of a first enclosure tube and a mating machined second end of a second enclosure tube which has a gas-escape path running from the inside to the outside of the enclosure tubes. The connection portion comprises a bracket surrounding the first end and the second end, whereby current flows from the first enclosure to second enclosure via the bracket. Thereby, contact force comes from gas pressure inside the enclosure after filling the enclosure with gas, which is sufficient for a normal flange connection.

However, for a compensation element such solution only works when the two enclosures tubes are completely separated as shown in the Fig. 6 of WO 2022/017584 A1. In any intermediate state, which is a normal installation case allowing contraction as well as expansion of the enclosure tubes, the defined contact force on a moving enclosure tube will be undefined and therefore, enclosure current will probably be interrupted. In addition, protection measures against corrosion in outdoor and in harsh conditions as known from WO 2022/017584 A1 will probably not be sufficient to guarantee gas tightness and enclosure current flow. Thus, over an expected lifetime of 25 to 40 years the solution described in WO 2022/017584 A1 may not work as intended, in particular in outdoor conditions and in harsh environments.

Summary of invention

It is therefore an object of the invention to provide an improved enclosure for a gas- insulated medium-voltage or high-voltage apparatus and a respective method for improving a current flow from a first enclosure tube to a second enclosure tube of an enclosure for a gas-insulated medium-voltage or high-voltage apparatus, in particular over an expected lifetime of 25 to 40 years and/or in outdoor conditions and in harsh environments.

The object of the invention is solved by the features of the independent claims. Preferred implementations are detailed in the dependent claims.

Thus, the object is solved by an enclosure for a gas-insulated medium-voltage or high-voltage apparatus comprising a first enclosure tube and a second enclosure tube, both having a longitudinal axis and in particular a radial thickness, and a connection portion arranged axially between the first enclosure tube and the second enclosure tube, whereby the connection portion is configured for providing a gas-tight connection between a first end of the first enclosure tube and a second end of the second enclosure tube, whereby the connection portion comprises a bracket surrounding the first end (20) and the second end, and whereby a coating, a machining, grease and/or a contact element is provided between the first enclosure tube, the second enclosure tube and/or between the bracket.

A key aspect of the proposed solution is therefore to improve the contact resistance for a standard flange connection by coating, machining and/or by providing a contact element. Such way flange connections known from prior art, in particular from WO 2022/017584 A1 , are substantially improved in respect to an expected lifetime of 25 to 40 years for the enclosure, in particular in outdoor conditions and in harsh environments. Thus, with the proposed solution contact in particular for a return current is significantly improved for the normal flange, thereby resulting in increased operational stability and lesser maintenance. Further, as explained below, sealing against corrosion is improved such that leakage is reduced.

The first enclosure tube and/or the second enclosure tube preferably comprise a substantially cylindrical shape or symmetry. The terms "radial", "axial" and "circumferential" refer to the longitudinal axis of the enclosure, in particular to the first enclosure tube and/or the second enclosure, having preferably a substantially cylindrical shape or symmetry. The terns a coating, a machining and/or a contact element should be understood that equally one or more i.e. a plurality of coatings, machining and/or contact elements can be provided.

According to a preferred implementation, the coating, the machining and/or the contact element is provided between the first enclosure tube and the bracket and/or between the second enclosure tube and the bracket and/or between the first enclosure tube and the second enclosure tube. Preferably, the coating is attached and/or machining is provided on axial and/or radial surfaces between the first enclosure tube and/or the second enclosure tube. Equally, the contact element is preferably provided on axial and/or radial surfaces between the first enclosure tube and/or the second enclosure tube. More preferably, all axial and/or radial surfaces between the first enclosure tube and/or the second enclosure tube are coated and/or machined and/or a plurality of contact elements are provided between the first enclosure tube and the second enclosure tube.

In another preferred implementation the coating is provided as silver plating, the machining is provided as riffles and/or the contact element is provided as spiral contact and/or as lamella contact. Instead of or in addition to silver plating, gold plating, copper plating, rhodium plating, chrome plating, zinc plating, tin plating, alloy plating or a composite plating can be used. Machining is preferably carried out during manufacturing of the enclosure tubes or can be carried out during installation of the enclosure.

According to a further preferred implementation, the enclosure comprises a sealing element arranged preferably radially between the first end and the second end and configured for providing the gas-tight connection. The sealing element is preferably provided as a sealing ring, in particular arranged radially between the first end and the second end. Preferably, at least two distant but adjancent sealing elements are provided. The sealing element preferably comprises EPDM, ethylene propylene diene monomer rubber, NBR, nitril butyl rubber, FEP, perfluorethylene propylene copolymer, PFA, polyfluoroalkoxy coploymer, PTFE, polytetrafluoroethylene, and/or a combination thereof.

In another preferred implementation the contact element arranged axially adjacent to the sealing element and/or, in case of a plurality of sealing elements, arranged axially between the plurality of sealing elements. Thus, in axial direction, different contact elements can be arranged, for example, before, between and/or after the sealing elements.

In a further preferred implementation, the bracket is configured for either allowing or disallowing a limited axial movement of the first end and the second end relative to each other. The term allowing a limited axial movement means preferably that the first enclosure tube and the second enclosure can axially move relative to each other, for compensating thermal elongation or contraction or axial length tolerances, while the gas-tight connection is maintained. The term disallowing means that the first enclosure tube and the second enclosure cannot move axially in respect to each other.

According to a further preferred implementation, the bracket defines, when allowing the limited axial movement of the first end and the second end relative to each other, together with the first end and the second end an axial expansion gap and the axial expansion gap is filled with the grease and/or anodized. By filling the axial expansion gap with the grease and/or by anodizing the axial expansion gap, in particular surfaces of the axial expansion gap, respective surfaces can be protected against corrosion. Preferably, the bracket defines two axially arranged opposite axial expansion gaps, each radially covered by the bracket respectively a connection portion as described below. An axial width of the axial expansion gap preferably changes due to the axial movement.

In another preferred implementation the bracket surrounds the first end and the second end and configured for applying an axial holding force for holding the first end and the second end together. The bracket is preferably ring-shaped and/or comprises a U-shaped cross section to be arranged around the enclosure tubes. The bracket may comprise an axial slit for assembling the bracket onto the enclosure tubes. Circumferential grooves or indentures can be provided in the enclosure tubes, into which the U-shaped bracket can be snapped into. A heat-shrink tube be positioned around the bracket for respectively covering the bracket.

According to a further preferred implementation, the bracket is provided ring-shaped having a diameter and axial width adapted to the first and second enclosure tube and comprises an axial slit configured for supplying the axial expansion gap with the grease. The axial slit can have a slid width in a range of 0.2 mm to 25 mm, preferable in a range of 5 mm to 15 mm. By providing such axial slit the axial expansion gap can be easily filled with the grease. The axial expansion gap may comprise, in a side view, a rectangular shape that extends circumferential around the enclosure tube. In another preferred implementation the bracket comprises an axial bracket width covering and length wise matched to the bracket or made longer than the bracket for improving a mutual axial alignment of the first and second enclosure tube and/or for compensating a thermal length extension of the enclosure.

According to a further preferred implementation, the bracket comprises a grease nipple configured for supplying the axial expansion gap with grease. Alternatively, a grease fitting, a zerk fitting, a grease zerk, and/or an alemite fitting can be provided. The grease nipple can be made from zinc-plated steel, stainless steel, or brass. Such grease nipple allows easy regreasing.

In another preferred implementation the first end and the second end at least partially overlap radially. Preferably the first end and the second radially overlap axially along the connection portion and/or the bracket or at least partially axially along the connection portion and/or the bracket. Thereby, the first end and/or the second end may comprise a radially reduced thickness compared to the first enclosure tube and/or the second enclosure tube axially outside the first end and/or the second. Preferably, the first end and the second end are radially arranged touching to each other.

According to a further preferred implementation, the enclosure comprises pressurized gas provided in the first enclosure tube and in the second enclosure tube. The gas is preferably provided as an insulation gas, such as, for example, air, CO2, N2, SF6 or an insulation gas mixture. The term high voltage means preferably a voltage ranging from 36 to 1 ,100 kV. A high voltage preferably relates to nominal voltages in the range from above 72 kV to 550 kV, like 145 kV, 245 kV or 420 kV, or even more. Nominal currents can be in the range from 1 kA to 8 kA, even higher such as 80 kA for one second. Short circuit currents exceeding 80 kA for several seconds can be considered covered. The term medium voltage preferably means a voltage lower than the high voltage.

The object is further solved by a method for improving a current flow from a first enclosure tube to a second enclosure tube of an enclosure for a gas-insulated medium-voltage or high-voltage apparatus, comprising the first enclosure tube and the second enclosure tube, both having a longitudinal axis and in particular a radial thickness, and a connection portion arranged axially between the first enclosure tube and the second enclosure tube, whereby the connection portion is configured for providing a gas-tight connection between a first end of the first enclosure tube and a second end of the second enclosure tube, whereby the connection portion comprises a bracket surrounding the first end and the second end, and comprising the step of providing a coating, a machining, grease and/or a contact element between the first enclosure tube, the second enclosure tube and/or between the bracket.

In another preferred implementation the method comprises the step of:

Filling an axial expansion gap defined by the bracket, when allowing the limited axial movement of the first end and the second end relative to each other, together with the first end and the second end with grease and/or anodizing the axial expansion gap.

Further implementations and advantages of the method are directly and unambiguously derived by the person skilled in the art from the enclosure as described before.

Brief description of drawings

These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.

In the drawings:

Fig. 1 shows a partial cross-sectional side view of an integrated flange design as known from Fig. 6 of WO 2022/017584 A1 ,

Fig. 2 shows the partial cross-sectional side view of an integrated flange design of Fig. 1 according to a preferred implementation, and Fig. 3 shows the partial cross-sectional side view of an integrated flange design of Fig. 1 according to a further preferred implementation.

Description of implementations

Fig. 1 shows a partial cross-sectional side view of an integrated flange design as known from Fig. 6 of WO 2022/017584 A1 . Said prior art document describes a gastight enclosure 1 made from metal has busduct segments that comprise first and second enclosure tubes 2, 3 aligned in respect to their longitudinal axis and connected together at a connection portion 4 respectively flange. The enclosure 1 houses a central conductor, not shown, that is suspended in insulation gas compartments, not shown, thereby forming a single phase encapsulated gas-insulated line or generally gas-insulated apparatus.

WO 2022/017584 A1 further describes that the busduct enclosure tubes 2, 3 are solidly grounded and electrically connected to each other. The conductors are connected to the high-voltage source. The insulation gas compartments of the busducts are filled with an insulation gas, such as air, CO2 , N2, SF6 or insulation gas mixtures at elevated pressure. Typical insulation gas pressures are in a range from 3 bar to 10 bar. The integrated flange design can be used to connect gas-insulated switchgear components other than a gas-insulated line, such as, for example, circuit breakers, disconnectors, busbars, earthing switches, compensator elements, angle connections, end covers, etc.

WO 2022/017584 A1 further describes that the enclosure tubes 2, 3 have said connection portion 4 or integrated flange arranged there-between. Said connection portion 4 respectively a bracket 6 provides a gas-tight connection between a first end 20 of the first enclosure tube 2 and a second end 30 of the second enclosure tube 3 and allows a limited axial movement of the first end 20 and the second end 30 relative to each other. Therefore, the first end 20 comprises an outwardly oriented first connection face 21 having a first recession 23 at an outside of the enclosure 1 . The second end 30 comprises an inwardly oriented second connection face 31 having a second protrusion 32 at the outside mating with the first recession 23 and a second recession 33 at the inside of the enclosure 1 mating with the first protrusion 22. The first protrusion 22 has on its outer face 22o oriented towards the second protrusion 32 two sealing grooves 50 running circumferentially with a therein respective arranged sealing ring 5a, 5b, in particular an o-ring, of the sealing element 5.

Said Fig. 6 of WO 2022/017584 A1 respectively Fig. 1 further shows that the connection portion 4 comprises the U-shaped fixation bracket 9 surrounding the first end 20 and the second end 30 for providing an axial holding force holding the first end 20 and the second end 30 together and for providing an electrical connection 7 for enclosure currents between the enclosure tubes 2, 3. The bracket 9 has a partial ring shape with an axial slit, not shown, which allows for an elastic snap fit of the bracket 9 onto the connection portion 4. Walls of bracket grooves or indentures are pressed onto respective bracket teeth or rims within the enclosure tubes 2, 3 by an elevated gas pressure inside the enclosure 1 . The bracket 9 is radially outward covered with a heat shrink tube 11 .

An axial expansion gap 112 is provided for allowing relative movement of the first end 20 of the first enclosure tube 2 and the second end 30 of the second enclosure tube 3, in particular for compensating thermal elongation or contraction or axial length tolerances of the first and/or second enclosure tubes 2, 3 without compromising the gas-tight sealing between the first end 20 and the second end 30. On the other side, the U-shaped fixation bracket 9 radially covering respectively snapped into the first enclosure tube 2 and the second enclosure tube 3 limits the axial movement of the first and/or second enclosure tubes 2, 3.

Said electrical connection 7 only works in a reliable manner when the two enclosure tubes 2, 3 are completely separated as shown in Fig. 1. In any intermediate state which a shorter axial expansion gap 112, which is a normal installation case to allow contraction as well as expansion of the two enclosure tubes 2, 3, a defined contact force on a moving side will be interrupted. Thus, for improving a contact resistance between the two enclosure tubes 2, 3 and the connection portion 4 respectively the bracket 9, a respective coating 8, for example, silver plating, and/or machining 8, for example, riffles to reduce resistance, is applied to a respective radial and/or axial surfaces between the two enclosure tubes 2, 3 and the connection portion 4 respectively the bracket 9, as shown in Fig. 2.

Alternatively or in addition, as shown in Fig. 3, one or a plurality of contact elements 10 can be provided arranged at axial surfaces between the two enclosure tubes 2, 3 and the connection portion 4 respectively the bracket 9 and/or between the two enclosure tubes 2, 3. Said contact elements 10 are arranged between the two enclosure tubes 2, 3 can be provided, in axial extension, before, between and/or the sealing rings 5, 5a, 5b, or in any favorable combination. The contact elements 10 can be provided as spiral contact and/or as lamella contact, and create parallel current paths for lowering overall contact resistance.

Said connection portion 4 respectively bracket 9 provides two functions, namely providing the electrical connection 7 between two enclosure tubes 2, 3 and providing a seal against loss of gas provided in the enclosure 1. WO 2022/017584 A1 describes before mentioned heat shrink tube 11 as protection against corrosion. However, spaces between the two enclosure tubes 2, 3, in particular the axial expansion gap 112, can accumulate condensed water, which leads to corrosion and/or higher resistance, which subsequently leads to increased flange temperature and/or higher surface roughness and possible gas leaks.

Thus, the axial expansion gap 112 is filled with grease and/or surfaces of the axial expansion gap 112 i.e. surfaces of the two enclosure tubes 2, 3 and the bracket 9 are anodized. In other words, spaces between the two enclosure tubes 2, 3 and the bracket 9 are filled with grease, for example by injection through a slit in the bracket 9 during installation or by adding a dedicated grease nipple on the bracket 9. Such way easy regreasing can be done without disassembly of the flange. Thereby, instead of the heat shrinkable tube 11 a heat shrinkable bandage would be suitable after a repair or maintenance action.

As a sum of volumes of both axial expansion gaps 112 stay constant, the injected grease will be pushed from one volume between to another volume when the second enclosure tube 3 expands. A respective path for the grease is either through a gap provided in the bracket 9 or via the small gap between the moving second enclosure tube 3 and the bracket 9.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed implementations. Other variations to be disclosed implementations can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of 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 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 scope.

Reference signs list

1 enclosure

2 first enclosure tube

3 second enclosure tube

4 connection portion

5, 5a, 5b sealing element

7 electrical connection

8 coating and/or machining

9 bracket

10 contact element

11 heat shrink tube

20 first end

21 first connection face

22 first protrusion

22o outer face

23 first recession

30 second end

31 second connection face

32 second protrusion

33 second recession

50 sealing groove

112 axial expansion gap

Claims

1 . Enclosure (1 ) for a gas-insulated medium-voltage or high-voltage apparatus comprising a first enclosure tube (2) and a second enclosure tube (3), both having a longitudinal axis (z), and a connection portion (4) arranged axially between the first enclosure tube (2) and the second enclosure tube (3), whereby the connection portion (4) is configured for providing a gas-tight connection between a first end (20) of the first enclosure tube (2) and a second end (30) of the second enclosure tube (3), whereby the connection portion (4) comprises a bracket (9) surrounding the first end (20) and the second end (30), and whereby a coating (8), a machining (8), grease and/or a contact element (10) is provided between the first enclosure tube (2), the second enclosure tube (3) and/or between the bracket (9).

2. Enclosure (1 ) according to the previous claim, whereby the coating (8), the machining (8) and/or the contact element (10) is provided between the first enclosure tube (2) and the bracket (9) and/or between the second enclosure tube (3) and the bracket (9) and/or between the first enclosure tube (2) and the second enclosure tube (3).

3. Enclosure (1 ) according to any of the previous claims, whereby the coating (8) is provided as silver plating, the machining (8) is provided as riffles and/or the contact element (10) is provided as spiral contact and/or as lamella contact.

4. Enclosure (1 ) according to any of the previous claims, comprising a sealing element (5, 5a, 5b) arranged preferably radially between the first end (20) and the second end (30) and configured for providing the gas-tight connection.

5. Enclosure (1 ) according to the previous claim, comprising the contact element arranged axially adjacent to the sealing element (5, 5a, 5b) or, in case of a plurality of sealing elements (5, 5a, 5b), arranged axially between the plurality of sealing elements (5, 5a, 5b).

6. Enclosure (1 ) according to any of the previous claims, whereby the bracket (9) is configured for either allowing or disallowing a limited axial movement of the first end (20) and the second end (30) relative to each other.

7. Enclosure (1 ) according to the previous claim, whereby the bracket (9) defines, when allowing the limited axial movement of the first end (20) and the second end (30) relative to each other, together with the first end (20) and the second end (30) an axial expansion gap (112) and the axial expansion gap (112) is filled with the grease and/or anodized.

8. Enclosure (1 ) according to any of the previous claims, whereby the bracket (9) is provided ring-shaped having a diameter and axial width adapted to the first and second enclosure tube (2, 3) and comprises an axial slit configured for supplying the axial expansion gap (112) with the grease.

9. Enclosure (1 ) according to any one of the previous two claims, whereby the bracket (9) comprises an axial bracket width covering and length wise matched to the connection portion (4) or made longer than the connection portion (4) for improving a mutual axial alignment of the first and second enclosure tube (2, 3) and/or for compensating a thermal length extension of the enclosure (1 ).

10. Enclosure (1 ) according to any of the three previous claims, whereby the bracket (9) comprises a grease nipple configured for supplying the axial expansion gap (112) with the grease.

11 . Enclosure (1 ) according to any of the previous claims, whereby the first end (20) and the second end (30) at least partially overlap radially.

12. Enclosure (1 ) according to any of the previous claims, comprising pressurized gas provided in the first enclosure tube (2) and in the second enclosure tube (3).

13. Method for improving a current flow from a first enclosure tube (2) to a second enclosure tube (3) of an enclosure (1 ) for a gas-insulated medium-voltage or high- voltage apparatus, comprising the first enclosure tube (2) and the second enclosure tube (3), both having a longitudinal axis (z), and a connection portion (4) arranged axially between the first enclosure tube (2) and the second enclosure tube (3), whereby the connection portion (4) is configured for providing a gas-tight connection between a first end (20) of the first enclosure tube (2) and a second end (30) of the second enclosure tube (3), whereby the connection portion (4) comprises a bracket (9) surrounding the first end (20) and the second end (30), and comprising the step of providing a coating (8), a machining (8), grease and/or a contact element (10) between the first enclosure tube (2), the second enclosure tube (3) and/or between the bracket (9).

14. Method according to the previous claim, comprising the step of:

Filling an axial expansion gap (112) defined by the bracket (9), when allowing the limited axial movement of the first end (20) and the second end (30) relative to each other, together with the first end (20) and the second end (30) with the grease and/or anodizing the axial expansion gap (112).