WO2019183964A1

WO2019183964A1 - An air insulated switchgear and an electrical system comprising the same

Info

Publication number: WO2019183964A1
Application number: PCT/CN2018/081455
Authority: WO
Inventors: Xiaobo Huang
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2018-03-30
Filing date: 2018-03-30
Publication date: 2019-10-03
Anticipated expiration: 2020-09-30

Abstract

It relates to an air insulated switchgear 200,400,500',500") and an electrical system(600) comprising the air insulated switchgear ( 200,400,500',500"). The air insulated switchgear ( 200,400,500',500") includes a busbar compartment ( 210,410,510',510"), adapted to accommodate at least two main busbars ( 212a,212b,212c,412,512',512") and at least two branch busbars ( 214a,214b,214c,414,514',514") for at least two phases, wherein the at least two main busbars ( 212a,212b,212c,412,512',512") are arranged in a front to back direction of the air insulated switchgear ( 200,400,500',500") and wherein each of the at least two branch busbars ( 214a,214b,214c,414,514',514") is connected to a corresponding one of the at least two main busbars ( 212a,212b,212c,412,512',512") substantially perpendicularly. With the arrangement as proposed herein, it is possible to provide a compact switchgear with a lower line loss at a low cost.

Description

AN AIR INSULATED SWITCHGEAR AND AN ELECTRICAL SYSTEM COMPRISING THE SAME

FIELD OF THE INVENTION

The non-limiting and exemplary embodiments of the present disclosure generally relate to the field of electrical devices, and more particularly relate to an air insulated switchgear and an electrical system including the air insulated switchgear.

BACKGROUND OF THE INVENTION

A switchgear, which is usually also called as switch cabinet, is an electric device which is adapted to switch on or off, control and protect electrical equipment during power generation, transmission, distribution, and power conversion. The switchgear can be classified in many manners. For example, it could be classified, in terms of functionalities, into incoming panel, disconnection panel, feeder panel, bustie panel, busriser panel, metering panel and potential transformer panel. In addition, according to different voltage levels, it could also be categorized into a low voltage switchgear, a high voltage switchgear and a medium voltage switchgear.

In air insulated switchgear, there are usually accommodated electric components such as circuit breakers, disconnectors, load switches, operating mechanisms, transformers, various protection devices and so on. Generally, the switchgear can be divided into different compartments such as a busbar compartment, a circuit breaker compartment, a cable compartment, and a low voltage compartment. In addition, it may also provide a pressure relief passage on the top of the busbar compartment, if required, so as to release arcing air pressure in an even of arc generation.

The air insulated switchgear has a big size and, in many practice applications, it requires more than one air insulated switchgear, which means a large space occupation and a high cost. In addition, low line loss, and easy maintenance are also constant demands of the air insulated switchgear. Thus, there is a need in the art to improve the design of air insulated switchgear.

SUMMARY OF THE INVENTION

Various embodiments of the present disclosure mainly aim at providing a solution for an air insulated switchgear and an electrical system including the air insulated switchgear to solve or at least partially mitigate at least a part of problems in the prior art. Other features and advantages of embodiments of the present disclosure will also be understood from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the present disclosure.

According to a first aspect of the present disclosure, there is provided an air insulated switchgear. The air insulated switchgear may include a busbar compartment, adapted to accommodate at least two main busbars and at least two branch busbars for at least two phases. The at least two main busbars are arranged in a front to back direction of the air insulated switchgear and each of the at least two branch busbars is connected to a corresponding one of the at least two main busbars substantially perpendicularly. Such arrangement of the main busbars could provide enough inter-phase distance so that a branch busbar could be connected to a corresponding main busbar substantially perpendicularly without bending. Thus, it is possible to reduce the length of a main loop in the air insulated switchgear, which means a compact design, a lower line loss and also a low cost.

In an embodiment of the present disclosure, the at least two main busbars can be arranged substantially in the same level. Such a design could make the design more compact.

In another embodiment of the present disclosure, the air insulated switchgear may include a circuit breaker and at least two current transformers for the at least two phases, wherein the circuit breaker may be adapted to contact with the at least two branch busbars by corresponding upper contacts and contact directly with upper terminals of the at least two current transformers by corresponding lower contacts. In the air insulated switchgear, the lower contacts could be connected with the upper terminals of the current transformers without additional connection busbars and thus, fewer joints are used, which means both a lower line loss and lower cost.

In a further embodiment of the present disclosure, each of the at least two branch busbars can be in line with an upper terminal of a corresponding one of the at least two current transformers. This design could make the length of the main loop in the air insulated switchgear as short as possible.

In a still further embodiment of the present disclosure, each of the at least two branch busbars can be in line with a lower terminal of the corresponding one of the at least two current transformers. This design could further make the length of the main loop in the air insulated switchgear as short as possible.

In a yet further embodiment of the present disclosure, a lower terminal of each of the at least two current transformers may be configured to be directly connected to a cable in a cable compartment. The lower terminals of the current transformers can function as the lower branch busbars in the cabinet compartment and thus fewer joints are used, which means both a lower line loss and lower cost.

In another embodiment of the present disclosure, the air insulated switchgear may further include at least two extension cable connection busbars each connected to and transversely extending from a lower terminal of a corresponding one of the at least two current transformers, wherein each of the at least two extension cable connection busbars may be adapted to be connected with a cable in the cable compartment. This extension cable connection busbars could provide more cable connection terminals for connecting the cables.

In a further embodiment of the present disclosure, the air insulated switchgear may further include a circuit breaker compartment adapted to accommodate a circuit breaker and a cable compartment adapted to accommodate cables, wherein the busbar compartment, the circuit breaker compartment, and the cable compartment are arranged on top of each other in the vertical direction. Such a design of compartments makes the modularization production of the air insulated switchgear possible.

In a still embodiment of the present disclosure, the air insulated switchgear may further include a pressure relief passage adapted to release arcing pressure in an event of arc generation, wherein the pressure relief passage may be located on the top of the cable compartment and adjacent to both the busbar compartment and the circuit breaker compartment. Such arrangement of the pressure relief passage could reduce the height of the air insulated switchgear, provide a good heat dissipation condition for the busbar and make it easy to maintain the busbars.

In another embodiment of the present disclosure, the air insulated switchgear may further include at least two potential transformers for the at least two phases, wherein the at least two potential transformers are connected to the at least two branch busbars for measuring the voltage of the main busbars. In this way, the proposed solution could be used in a metering cabinet like potential transformer cabinet.

In a further embodiment of the present disclosure, the air insulated switchgear may further comprise a circuit breaker and at least two current transformers for the at least two phases, wherein the at least two current transformers may be located between the air insulated switchgear and another air insulated switchgear, and wherein the circuit breaker may be adapted to contact with the at least two branch busbars by corresponding upper contacts and contact directly with first terminals of the at least two current transformers by corresponding lower contacts.

In a still further embodiment of the present disclosure, each of the at least two branch busbars can be perpendicular to a first terminal of a corresponding one of the at least two current transformer. With this arrangement, the proposed solution could be applied in the busbar sectionalizer cabinet.

In another embodiment of the present disclosure, the air insulated switchgear may further comprise a switch for the at least two phases, wherein the switch has one end adapted to be connected with the at least two branch busbars and has the other end adapted to be connected with second terminals of at least two current transforms for the at least two phases. With this arrangement, the proposed solution could be applied in the busbar riser cabinet.

In a further embodiment of the present disclosure, wherein the least two main busbars are arranged face to face with each other, and the least two branch busbars are arranged face to face with each other, and wherein the at least two phases are three phases, .

In another aspect of the present disclosure, there is further provided an electrical system comprising at least one air insulated switchgear according to the first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent, by way of example, from the following detailed description with reference to the accompanying drawings, in which like reference numerals or signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and not necessarily drawn to scale, in which:

Fig. 1 schematically illustrates an example structure of an air insulated switchgear in the prior art;

Fig. 2A schematically illustrates a side view of an air insulated switchgear with the side panel removed according to an embodiment of the present disclosure;

Fig. 2B schematically illustrates a sectional view of the air insulated switchgear taken along line C-C according to an embodiment of the present disclosure;

Fig. 2C illustrates comparison of interphase distance between the existing arrangement in the prior art and the proposed arrangement according to an embodiment of the present disclosure.

Figs. 3A to 3C schematically illustrate a partial enlarged view of the current transformer according to an embodiment of the present disclosure; and

Fig. 4 schematically illustrates a side view of the air insulated switchgear as a metering cabinet according to an embodiment of the present disclosure;

Fig. 5 schematically illustrates a side view of the air insulated switchgear as a busbar sectionalizer cabinet and a busbar riser cabinet according to an embodiment of the present disclosure; and

Fig. 6 schematically illustrates an example system including at least one air insulated switchgear according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the principle and spirit of the present disclosure will be described with reference to illustrative embodiments. It shall be understood, all these embodiments are given merely for one skilled in the art to better understand and further practice the present disclosure, but not for limiting the scope of the present disclosure. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. In the interest of clarity, not all features of an actual implementation are described in this specification.

References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” etc. indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that, although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be liming of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. It will be also understood that the terms “connect (s) , ” “connecting” , “connected” , etc. when used herein, just means that there is an electrical connection between two elements and they can be connected either directly or indirectly, unless explicitly stated to the contrary.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As mentioned in Background, the air insulated switchgear has a big size and in many practice applications, it requires more than one switchgear. In the market, there are various types of air insulated switchgear available, but they are still required to be further improved, especially in terms of miniaturization, cost, line loss, heat dissipation, expedience, etc. For illustrative purposes, description will be first made to Fig 1 to briefly introduce an existing air insulated switchgear, wherein Fig. 1 illustrates an example switchgear in the art.

As illustrated in Fig. 1, the switchgear 100 defines an internal space by its housing including a front plate, a rear plate, a top plate, a bottom plate, and two side plates. The defined internal space is further divided, by means of internal metal partition plate, into four compartments including a busbar compartment 110, a circuit breaker compartment 120, a cable compartment 130, and a low voltage compartment 140. In addition, there may be also arranged a pressure relief passage 150 on the top of the busbar compartment 110. In these compartments are accommodated components such as three

main busbars

112a, 112b, 112c, three

branch busbars

114a, 114b, 114c in the busbar compartment, the circuit breaker 122, the upper branch busbar 132 in the cable compartment, the lower branch busbar 134 in the cable compartment, a current transformer 136 as well as secondary equipment required for protection and control functions.

The busbar compartment 110 is used to accommodate the main busbars l12a, l12b, 112c entering from outside as well as the branch busbars l14a, l14b, 114c for three phases. The busbars could be provided with full insulation (including joints) to ensure that the busbar system is a fault free zone as far as possible.

The circuit breaker compartment 120 is adapted to accommodate the circuit breaker 122, which could be for example a vacuum or SF6 circuit breaker mounted on a switch-truck. The circuit breaker 122 includes the upper contact arm 124a and the upper contact 126a, and the lower contact 126b and the lower contact arm 124b for each phase. For each phase, the upper contact 126a could be contacted with a corresponding branch busbar in the busbar compartment 110; the lower contact 126b could be contacted with the corresponding branch busbar 132 in the cable compartment 130. The upper contact arm 124a and the upper contact 126a may be housed in the upper contact spout 128a, and the lower contact 126b and the lower contact arm 124b may be housed in the lower contact spout 128b. The upper contact spout 128a and the lower contact spout 128b provide an electrical insulation between the upper contact arms and the metal partition plates and between the upper and lower contacts and the metal partition plate

The circuit breaker could be movable on the switch-truck between a service position and a test/disconnection position, and both of the service position and the test/disconnection position are all accommodated entirely within the switchgear 100. A shutter system 129 may comprises a plurality of shutter and it is further provided to cover the disconnected contacts when the circuit breaker is in the disconnection position, to provide true visual disconnection with earthing separation. The shutter system 129 could be opened when the breaker circuit operates at the service position and could be opened when the breaker circuit is pulled out to the disconnection position. In this way, it could shield the operator from the high electric field when pulling out of circuit breaker with door open.

In the cable compartment 130 are accommodated cables, current transformers, earthing switch, surge arrester, etc. The upper branch busbars 132 in the cable compartment could be contacted with corresponding lower contacts 126b on one end and connected to corresponding input terminals of the current transformers 136 on the other end. Corresponding output terminals of the current transformer 136 can be further connected to the lower branch branches 134 in the cable compartment, which can only be connected with limited number of the cables. The cable compartment 130 could provide a space for contacting multiple cable connections.

The low voltage compartment 140 provides a space to accommodate all secondary equipment required for protection and control functions. External control cables are terminated in the low voltage compartment 140 after entering through generous metal enclosed ducts.

The pressure relief passage 150 is further arranged on top of the busbar compartment 110 to release an arcing air pressure in an even of arc generation. In each of

high voltage compartments

110, 120, 130, there is provided a pressure relief plate. When an arc is generated, the resulting air pressure will push and open the pressure relief plate so that the pressured air can be released into the pressure relief passage.

As further illustrated in Fig. 1, the three

main busbars

112a, 112b, 112c are arranged one by one in the elevation direction. In other words, the main busbars are arranged in a top to down direction of the switchgear. In such a case the interphase insulation distance is limited. Thus, in order to grantee enough interphase insulation distance, the

branch busbars

114, 114b, 114c are first bent and then extended towards to the upper contact spout 128a.

The upper contact spout 128a and the lower contact spout 128b are used to support the fixed contacts and provide required an electrical insulation between the upper contact arms and the metal partition plates and between the upper and lower contacts and the metal partition plate. In addition, the circuit breaker 122 usually has tulip contacts and uses fixed contacts to connect with the

branch busbars

114a, 114b, 114c. Shutters in the shutter system 129 are near to the

contacts

126a, 126b and the

contact spout

128a, 128b when the circuit is located at the test/disconnection position and meanwhile they are near to the lower arm 126b when they are located at the service operation. Thus, it requires insulation treatments on the shutters. In addition, the upper and

lower contact arms

124a, 124b are designed long enough to provide sufficient length to connect with fixed contacts which are surrounded by spouts and there is a certain distance between the end of contact and surface of opening of spout

The branch busbars 134 in the cable compartment are arranged side by side, and thus auxiliary connection busbars 135 are used to provide more connection terminals which could be further connected with a plurality of cables. Thus, the main loop conductor in the cable compartment comprises the following parts: the upper branch busbar 132 in the cable compartment, the current transformer 136, and the lower branch busbar 134 in the cable compartment and possible extension cable connection busbar.

The design of the example existing switchgear has some disadvantages, such as line loss caused by the main loop design, cost issues due to the main loop design, the insulation design, and the material adopted. In addition, it is also not easy to install and maintain due to the design of the pressure relief passage. Moreover, its size is big and not satisfactory yet.

Thus, in the present disclosure, there is provided a new compact air insulated switchgear. Hereinafter, the air insulated switchgear as proposed herein will be described with reference to Figs. 2 to 6. However, it shall be appreciated, the air insulated switchgears given herein are only examples for illustrative purposes and the present disclosure is not limited thereto. In fact, the skilled in the art could modify the switchgear without departing the spirit of the present disclosure. In addition, the medium-voltage (MV) air insulated switchgear is taken as an example to describe the new air insulated switchgear as proposed in the present disclosure. However, the skilled in the art could understand that such design can be applied to high voltage application and low voltage applications too. Three phase applications are taken as examples to describe the air insulated switchgear herein, but the present disclosure is not limited thereto. The present disclosure can be applied to application for less or more phases.

Reference is first made to Figs. 2A and 2B, which respectively illustrate a side view of the air insulated switchgear with the side panel removed and a sectional view taken from line C-C according to an embodiment of the present disclosure. The example switchgear 200 is an air insulated switchgear for MV applications.

As illustrated in Fig 2A, the switchgear 200 defines an internal space by a housing including a front plate, a rear plate, a top plate, a bottom plate, and two side plates. The defined internal space is further divided, by means of inner metal partition plate, into four compartments including a busbar compartment 210, a circuit breaker compartment 220, a cable compartment 230, and a low voltage compartment 240.

As illustrated, different from the existing design, the busbar compartment is stacked over the circuit breaker compartment 220, and the circuit breaker compartment 220 is stacked over the cable compartment 230. Thus, the three

compartments

210, 220 and 230 are arranged in a top to bottom direction one by one. In other words, the busbar compartment 210, a circuit breaker compartment 220, and a cable compartment 230 are arranged on top of each other in the vertical direction. Such compartment design can achieve a modularization design and manufacture, which makes both further design and manufacture easily.

In addition, there is further arranged a pressure relief passage 250 on the top of the cable compartment 230 immediately adjacent to both the busbar compartment 210 and the circuit breaker compartment 220. In the example switchgear, the pressure relief passage 250 is arranged at the back side. In the illustrated switchgear, the pressure relief passage 250 is provided at the top rear part of the switchgear although it may also be located at other parts like left rear or right rear part of the switchgear. Different from the existing switchgear as illustrated in Fig. 1, the pressure relief passage 250 is not on the top of the busbar compartment 210 but at the top rear part. In such way, it will reduce the height of the switchgear. Therefore, The pressure relief passage 250 can be assembled onto the switchgear during manufacturing without installing it in the field. In addition, due to the fact that the pressure relief compartment is located by a side of the busbars compartment and the circuit breaker compartment, , it does will not cover the busbar compartment anymore and thus it will be an easy job to check the busbar compartment.

The busbar compartment 210 is used to accommodate at least main busbars and at least two branch busbars for at least two phases. In Fig. 2A and 2B, there are illustrated three

main busbars

212a, 212b, 212c as well as three

branch busbars

214a, 214b, 214c for three phases. The

main busbars

212a, 212b, 212b enter from outside through three wall bushings 211 respectively. Especially, the

main busbars

212a, 212b, 212c are arranged in a front to back direction of the switchgear and each of the

branch busbars

214a, 214b, 214c is connected to a corresponding one of the

main busbars

212a, 212b, 212c substantially perpendicularly. Thus, in the new switchgear, the three main busbars could enter, as a whole, the switchgear in the horizontal direction.

By contrast, the main busbars of the existing switchgear is arranged in a top to down direction or in the vertical direction. Unlike this, the main busbars of the switchgear as proposed herein are arranged in a front to back direction of the switchgear. In addition, the main busbars could be arranged face to face with each other, which could provide enough interphase insulation distance and insulation margins, and thus there is no need for bending of the branch busbars to ensure the interphase insulation distance and no need for further insulation treatment. For illustrative purposes, Fig. 2C illustrates comparison of interphase distance between the existing arrangement in the prior art and the proposed arrangement according to an embodiment of the present disclosure.

As illustrated in Fig. 2C, in the proposed arrangement, both the main busbars and the branch busbars are arranged face to face with each other, while in the existing arrangement, the main busbars and the branch busbars are arranged side by side. Thus, the proposed arrangement herein could achieve a larger interphase distance as illustrated in a case the same distance between centers. Accordingly, each of the

branch busbars

214a, 214b, 214c could be connected to a corresponding one of the

main busbars

212a, 212b, 212c substantially perpendicularly without any bending. In addition, the upper terminals and lower terminals of the current transformer can be arranged in a similar way.

At the same time, the three main busbars can all be arranged near the top of the switchgear and thus they are easy to be maintained. This may also provide a larger space therebetween, which could facilitate the heat dissipation. Moreover, by means of such arrangement of the main busbars, the three main busbars could dissipate generated heat evenly. Optionally, the

main busbars

212a, 212b, 212c can be arranged substantially in the same level to save the occupation space as far as possible. That is to say, the

main busbars

212a, 212b, 212c can be arranged substantially in the same horizontal level.

The

branch busbars

212a, 212b, 212c are arranged in the front to back direction accordingly, which also facilitate the heat dissipation. In addition, in such a case, the

branch busbars

212a, 212b, 212c can be cast as integral parts of respective isolation bushings 216 between the busbar compartment 210 and the circuit breaker compartment 220. In other words, upper terminals of the isolation bushing can function as the upper branch busbars for the busbar compartment and lower terminals of the isolation bushing can function as the lower branch busbars and fixed contacts for the circuit breaker. Thus, no additional fixed contacts are required. The upper terminals of the isolation bushing can be connected to the main busbars and the lower terminals of the isolation bushing can extend up to the upper contact of the circuit breaker.

The circuit breaker compartment 220 is located under the busbar compartment 210. The circuit breaker compartment 220 is adapted to accommodate the circuit breaker 222, which could be for example a vacuum or SF6 circuit breaker mounted on a switch-truck. The circuit breaker 222 includes three upper contact arms 224a and three upper movable contacts 226a and three lower movable contacts 226b and three lower contact arms 224b. The upper movable contacts 226a can use duckbill shaped contacts and thus could be connected with the lower terminals of the isolation bushings 216 without addition fixed contacts. In such a case, each of the

branch busbars

214a, 214b, 214c may be in line with an upper terminal of the corresponding one of the three current transformers 236. Optionally, each of the

branch busbars

214a, 214b, 214c is in line with a lower terminal of the corresponding one of the three current transformers 236. Similarly, the lower contacts 226b can also use duckbill shaped contacts and thus could be directly connected with the upper terminals 232 of the current transformer 236.

Due to the low cost of the duckbill shaped contacts, it is possible to reduce the cost. At the same time, no upper and lower contact spouts are required to provide insulation since the isolation bushings provide required insulation between the branch busbars and the metal partition plate and the upper and the lower upper contacts are located far enough from the metal partition plate which could provide sufficient insulation distance. In addition to the benefits regarding cost, this could further facilitate shortening of the contact arms since there is no any contact spout in the proposed switchgear and thus it does not require the arm long enough to insert into the contact spouts to connected with fixed contacts in contact spouts. Besides, it could eliminate effect of the contact spouts on heat dissipation and air convection and thus the high temperature on the contacts can be mitigated.

The shutters 228 can be driven by movement of the circuit breaker on the switch-truck. Particularly, when the circuit breaker is pushed from the outside of the switchgear to the test/disconnection position A (as illustrated in Fig. 2B) , the shutters are driven to open, while the circuit breaker is pulled from the test/disconnection A to outside of the switchgear, the shutters are closed by the acting force of a reset spring. In such way, it could shield the operator from high electric field when the circuit breaker is pulled out to the outside of the switchgear. In addition, the shutters 229 are far away from the high voltage area and thus there is no any additional insulation requirement. While in the existing switchgear, the shutters are near to the lower contact arm when the circuit breaker is operating, and they are near to the fixed contact when they are at the test/disconnection position. Thus it requires insulation for the shutter is necessary. Therefore, compared with the existing design, the shutter of the present disclosure could eliminate the requirement of insulation and thus could reduce the cost.

The cable compartment 230 is located under the circuit breaker compartment 220 in which can be accommodated cables, earthing switch, surge arrester, etc. The upper branch busbar 232 could be contacted with the lower contact 226b of the circuit breaker 222 and the lower branch busbar 234 in the cable compartment could be connected to the cables. The cable compartment 230 could provide a space for contacting multiple cable connections.

However, different from the existing switchgear, the current transformers 236 is no located entirely within the cable compartment 230 but located between the circuit breaker compartment 220 and the cable compartment 230, and upper and

lower terminal

232, 234 of the current transformers 236 could function as the upper and lower branch busbars in the cable compartment of the existing switchgear themselves, without additional upper and lower branch busbars provided in the cable compartment. For illustrative purposes, reference will made to Fig. 3 to describe the current transformer and the branch busbars in the cable compartment 230.

Fig. 3 schematically illustrates a partial enlarged view of the current transformer according to an embodiment of the present disclosure. The current transformers 236 are located between the circuit breaker compartment 220 and the cable compartment 230. Thus, upper terminals 232 of the current transformers 236 are located within the circuit breaker compartment and only their lower terminals 234 are located within the cable compartment. As illustrated in Fig. 3, the upper terminals 232 of the current transformer 236 could directly connected to the lower contacts 226b which are duckbill shaped contact, and thus unlike the existing switchgear, no additional fixed contacts and upper branch busbar in the cable compartment are used. The lower terminals 234 of the current transformers 236 can be used as cable connection terminals and be directly connected with cables. By means of such design, it could save the cost due to the omission of the lower branch busbars, and fewer joints are used which mean less line loss. At the same time, the lower terminals are arranged in a vertical direction, which will facilitate the heat dissipation as well.

As further illustrated in Figs. 3A to 3C, it may further provide an extension cable connection busbar 238 for each phase. Each extension cable connection busbar 238 can be connected to and transversely extending from the lower terminal 234 of a corresponding one of the current transformers 236. That is to say, the lower terminals of the current transformers extends in a vertical direction, while the extension cable connection busbar 238 can be extended in horizontal direction. In addition, the extension cable connection busbars can also be provided face to face with each other, thus enough spaces are provided and in turn each extension cable connection busbar can be connected with more cables in the cable compartment 230 without any subsidiary connection busbar.

The low voltage compartment 240 is located on the circuit breaker compartment 220 in front of the busbar compartment 210. The low voltage compartment provides a space to accommodate all secondary equipment required for protection and control functions. External control cables are terminated in the low voltage compartment 240 after entering through generous metal enclosed ducts.

Reference is made back to Figs. 2A and 2B. The pressure relief passage 250 is adapted to release an arcing air pressure in an even of an arc generation. In each of high voltage compartments, there are provided a pressure relief plate at position which could communicate with the pressure relief passage 250. When an arc is generated, the resulting air pressure pushes and opens the pressure relief plate so that the pressured air is released into the pressure relief passage.

In addition, from Fig. 2A and 2B, a main loop conductor may include the main busbar, the isolation bushing, the circuit breaker, the current transformer and extension branch busbar (if required) and the main loop conductor has a shorter length than that of the existing switchgear. The shorten length of the main loop conductor means a lower cost, a lower line loss and a fewer heat generation. In addition, in the proposed switchgear, there are fewer joints and thus the contact resistance can be further reduced, the line loss can be further lowered and the heat generation can be decreased.

Fig. 4 schematically illustrates a side view of another switchgear as metering cabinet according to an embodiment of the present disclosure. As an example, the metering cabinet is illustrated as a potential transformer cabinet which is adapted to measure the voltage of the main busbars. As illustrated in Fig 4, the metering cabinet 400 has a busbar compartment 410 for accommodating three main busbars 412 for three phases, and a metering compartment 460 for accommodating three potential transformers 466 for the three phases. Different from the arrangement of the main busbars in a top to down direction, the main busbars 412 are arranged in a front to back direction. Thus, the interphase insulation distance is enough and there is no need for bending of the branch busbars to ensure the interphase insulation distance. Accordingly, each of the branch busbars 414 could be connected to a corresponding one of the main busbars 412 substantially perpendicularly without any bending. Thus, the three main busbars can all be located near the top of the switchgear and thus easy to be maintained, and it may also provide a larger space there among, which could facilitate the heat dissipation. Moreover, by means of such arrangement of the main busbars, the three main busbars could dissipate generated heat evenly. Optionally, the main busbars 412 can be arranged substantially in the same horizontal level to save the occupation space as far as possible.

In addition, the branch busbars 414 are arranged in the front to back direction accordingly, which also facilitate the heat dissipation. In addition, each of the branch busbars 414 can be cast as an integral part of a corresponding one of isolation bushings 416 between the busbar compartment 410 and the circuit breaker compartment 420. The upper and lower terminals of the isolation bushings 416 can function as the upper and lower branches for the busbar compartment. Thus, the upper terminals of the isolation bushings 416 can be directly connected to the main busbars and lower terminals of the isolation bushings 416 can be connected with an arrester 462 and a transform branch busbar which is further connected to the potential transformer 466 for voltage measurement. In the metering cabinet, there is further provided an earthing switch 463.

Fig. 5 schematically illustrates a side view of the switchgear as busbar sectionalizer cabinet 500’ and busbar riser cabinet 500” according to an embodiment of the present disclosure. The busbar sectionalizer cabinet 500’ and busbar riser cabinet 500” could be used together to provide the current measurement of the main busbars. The busbar sectionalizer cabinet 500’ is adapted to measure currents of the main busbars and the busbar riser cabinet is adapted to raise the busbar from a lower level to a regular higher level.

As illustrated in Fig. 5. The busbar sectionalizer cabinet 500’ includes a busbar compartment 510’, a circuit breaker compartment 520’ and an empty compartment 530’, while the busbar riser cabinet is not further divided and the whole cabinet is adapted to accommodate the busbars, which can be considered as a busbar compartment. The busbar compartment 510’ is adapted for accommodating three main busbars 512’ for three phases, and the circuit breaker compartment 520’ is adapted for accommodating the circuit breaker for the three phases. Different from the arrangement of the main busbars in a top to down direction, the main busbars 512’ are arranged in a front to back direction. Thus, the interphase insulation distance is enough and there is no need for bending of the branch busbars to ensure the interphase insulation distance. Accordingly, each of the branch busbars 514’ could be connected to a corresponding one of the main busbars 512’ substantially perpendicularly without any bending. In this way, the three main busbars can all be located near the top of the switchgear and thus easy to be maintained, and it may also provide a larger space there among, which could facilitate the heat dissipation. Moreover, by means of such arrangement of the main busbars, the three main busbars could dissipate generated heat evenly. Optionally, the main busbars 512’ can be arranged substantially in the same horizontal level to save the occupation space as far as possible.

In addition, the branch busbars 514’ can be arranged from in the front to back direction of the switchgear accordingly, which also facilitate the heat dissipation. In addition, the branch busbars 514’ can be cast as an integral part of the isolation bushing 516’ between the busbar compartment 510’ and the circuit breaker compartment 520’. The upper and lower terminals of the isolation bushings 516’ can function as the upper and lower branches for the busbar compartment. Thus, the upper terminals of the isolation bushings 516’ can be directly connected to the main busbars and lower terminals of the isolation bushings 516’ can be connected to the upper contacts of the circuit breaker 522’ whose lower contacts are further connected to the current transformer 536 for current measurement.

Different from the switchgear illustrated in Figs. 2A and 2B, the current transformer 536 is not located between the circuit breaker compartment 520’ and the empty compartment 530’ but located between the circuit breaker compartment 520’ and the busbar riser cabinet 500”. The circuit breaker 522’ can contact with the at least two branch busbars 514’ by corresponding upper contacts and contact directly with first terminals 531 of the at least two current transformers 536 by corresponding lower contacts. Thus, each of the three branch busbars 514’ is not in line with but perpendicular to first terminal 531 of a corresponding one of the at least two current transformers 536.

As further illustrated in Fig. 5, in the busbar riser cabinet 500”, the main busbars 512” are also arranged in a front to back direction of the switchgear. Thus, the interphase insulation distance is enough and there is no need for bending of the branch busbars to ensure the interphase insulation distance. Accordingly, each of the branch busbars 514” could be connected to a corresponding one of the main busbars 512” substantially perpendicularly without any bending. In this way, the three main busbars 512” can all be located near the top of the switchgear and thus easy to be maintained, and it may also provide a larger space there among, which could facilitate the heat dissipation. Moreover, by means of such arrangement of the main busbars, the three main busbars could dissipate generated heat evenly. Optionally, the at least two main busbars 512” can be arranged substantially in the same horizontal level to save the occupation space as far as possible.

In busbar riser cabinet 500”, there are further provided a switch 562” for the three phases, the switch 562” has three blades for three phase, and it has one ends connected to branch busbars 514” and the other ends connected to the second terminals 533 of the current transformers 536.

In addition, by means of the new air insulated switchgear proposed here, it could form an electrical system or an electrical station. For illustration purposes, Fig. 6 schematically illustrates an electrical system including at least one air insulated switchgear according to an embodiment of the present disclosure. This is an example arrangement of a typical substation. However, it shall be understood that the switchgear as proposed herein may also form a different system from the illustrated substation.

As illustrated in Fig. 6, the system comprises a plurality of standard switchgear 100, two metering cabinets 400, a busbar sectionalizer cabinet 500’ and a busbar riser cabinet 500”. All the cabinets are arranged side by side and form the substation.

However, it could be understood that, the system 600 is only given for illustrative purposes and the system could include more switchgears or less switchgear than those illustrated and the arrangement of the switchgears can be different too.

In addition, the metering cabinet 400, the busbar riser cabinet 500”, the busbar sectionalizer cabinet 500’ and the electrical system 600 are described in brief with reference to Fig. 4 to 6 due to they have similar design to the switchgear as illustrated in Figs. 2 to 3B. Thus, for details about some design details or advantages, one could refer to the description with reference to Fig. 2 to Fig. 3B.

It can be appreciated that in the present disclosure, there are used some wordings such as “vertical” , “horizontal” , “level” , or their derivative, these words are used to explain the arrangement of components only, it might be different if the switchgear are positioned in different directions. In addition, in practical applications, they might not strictly follow the arrangement as proposed herein, there might be a reasonable difference. For example, the

branch busbars

214a, 214b, 214c may not strictly in line with the upper terminals of the at least two current transformers (236) . The branch busbars (514’) might not be strictly perpendicular to first terminals of the at least two current transformers (536) , either. However, such differences does not depart from the spirit of the present application and thus still fall within the scope of the present disclosure.

Hereinabove, embodiments of the present disclosure have been described in details through embodiments with reference to the accompanying drawings. It should be appreciated that, while this specification contains many specific implementation details, these details should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be drected to a sub-combination or variation of a sub-combination.

Various modifications, adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. Any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure. Furthermore, other embodiments of the disclosures set forth herein will come to mind to one skilled in the art to which these embodiments of the disclosure pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings.

Therefore, it is to be understood that the embodiments of the disclosure are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are used herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

An air insulated switchgear (200, 400, 500’, 500”) , comprising:

a busbar compartment (210, 410, 510’, 510”) , adapted to accommodate at least two main busbars (212a, 212b, 212c, 412, 512’ 512”) and at least two branch busbars (214a, 214b, 214c, 414, 514’, 514”) for at least two phases,

wherein the at least two main busbars (212a, 212b, 212c; 412, 512’, 512”) are arranged in a front to back direction of the air insulated switchgear and wherein each of the at least two branch busbars (214a, 214b, 214c; 414, 514’, 514”) is connected to a corresponding one of the at least two main busbars (212a, 212b, 212c; 412, 512’, 512”) substantially perpendicularly.
The air insulated switchgear (200, 400, 500’, 500”) of Claim 1, wherein the at least two main busbars (214a, 214b, 214c; 414, 514) are arranged substantially in the same level.
The air insulated switchgear (200, 500’) of Claim 1 or 2, further comprising a circuit breaker (222) and at least two current transformers (236) for the at least two phases, wherein the circuit breaker (222) is adapted to contact with the at least two branch busbars (214a, 214b, 214c) by corresponding upper contacts and contact directly with upper terminals of the at least two current transformers by corresponding lower contacts.
The air insulated switchgear (200) of Claim 3, wherein each of the at least two branch busbars (214a, 214b, 214c) is substantially in line with an upper terminal of a corresponding one of the at least two current transformers (236) .
The air insulated switchgear (200) of Claim 4, wherein each of the at least two branch busbars (214a, 214b, 214c) is in line with a lower terminal of the corresponding one of the at least two current transformers (236) .
The air insulated switchgear (200) of Claim 3, wherein a lower terminal of each of the at least two current transformers (236) is adapted to be directly connected to a cable in a cable compartment (230) .
The air insulated switchgear (200) of claim 6, further comprising at least two extension cable connection busbars (238) for the at least two phases, each connected to and transversely extending from a lower terminal of a corresponding one of the at least two current transformers (236) , wherein each of the at least two extension cable connection busbars (234) is adapted to be connected with a cable in the cable compartment (230) .
The air insulated switchgear (200) of Claim 1 or 2, further comprising a circuit breaker compartment (220) adapted to accommodate a circuit breaker and a cable compartment (230) adapted to accommodate cables, wherein the busbar compartment (210) , the circuit breaker compartment (220) , and the cable compartment (230) are arranged on top of each other in the vertical direction.
The air insulated switchgear (200) of Claim 8, further comprising a pressure relief passage (250) adapted to release arcing pressure in an event of arc generation, wherein the pressure relief passage (250) is located on the top of the cable compartment (230) and adjacent to both the busbar compartment (210) and the circuit breaker compartment (220) .
The air insulated switchgear (400) of Claim 1 or 2, further comprising at least two potential transformers (466) for the at least two phases, wherein the at least two potential transformers (466) are connected to the at least two branch busbars for measuring the voltage of the main busbars.
The air insulated switchgear (500’) of Claim 1 or 2, further comprising a circuit breaker (522’) and at least two current transformers (536) for the at least two phases, wherein the at least two current transformers (536) are located between the air insulated switchgear (500’) and another air insulated switchgear (500”) , and wherein the circuit breaker (522’) is adapted to contact with the at least two branch busbars (514’) by corresponding upper contacts and contact directly with first terminals of the at least two current transformers (536) by corresponding lower contacts.
The air insulated switchgear (500’) of Claim 11, wherein each of the at least two branch busbars (514’) is substantially perpendicular to a first terminal of a corresponding one of the at least two current transformers (536) .
The air insulated switchgear (500”) of Claim 1 or 2, further comprising a switch (562”) for the at least two phases, wherein the switch (562”) has one end adapted to be connected with the at least two branch busbars (511’) and has the other end adapted to be connected with second terminals of at least two current transforms (536) for the at least two phases located between the air insulated switchgear (500’) and another air insulated switchgear (500”) .
The air insulated switchgear (200, 400, 500’, 500”) of Claim 1 or 2, wherein the least two main busbars are arranged face to face with each other, and the least two branch busbars are arranged face to face with each other and wherein the at least two phases are three phases.
An electrical system (600) comprising at least one air insulated switchgear (200, 400, 500’, 500”) according to any one of Claims 1 to 14.