CN101577375B - High voltage bushing contact, high voltage bushing and high voltage device - Google Patents

Abstract

The invention concerns a high voltage bushing contact, comprising a first contact part (14) for connection with an electric device and a second contact part (16) for connection with a conductor (10) of the bushing, wherein the second contact part has an inner bore (18) with an opening for receiving an end of the conductor. The contact also comprises a set of mounting holes (22, 42) and a set of mounting members (24) adapted to be inserted through the mounting holes and by means of which both contact parts (14, 16) are secured to the end of the conductor (10), and that each mounting hole (22, 42) has a first opening inside the inner bore (18) of the second contact part (16). The invention also concerns a high voltage bushing comprising such a contact, and a high voltage device comprising such a bushing.

Description

High-voltage bushing joints, high-voltage bushings and high-voltage devices

technical field

The present invention relates to the field of high-voltage power systems, and in particular to joints for high-voltage bushings used in high-voltage installations forming parts of said systems.

Background of the invention

Known high-voltage equipment and installations such as high-voltage transformers, reactors, switchgear, etc. are usually equipped with bushings, which are suitable for carrying high-potential currents through earthing barriers - such as the walls of electrical installations such as transformer boxes. or housing.

A conventional high voltage bushing includes an insulator made of ceramic or composite material, the bushing is provided with a shed and is substantially hollow. On the inside of the bushing, voltage grading is achieved by a capacitor body or some other type of voltage grading device through which the electrical conductors pass. The electrical conductors are connected to one side of the bushing to which a high voltage electrical device is connected, and on the other side of the bushing to which another high voltage electrical device is connected. For example, when the first electrical device is a transformer, the bushing is mounted on the transformer housing, such as a tank wall, and the conductors of the bushing enable the inside of the transformer to be connected to another device such as a busbar, surge arrester or DC valve. The outside of the electrical device is connected.

In prior art bushings, the bottom end portion of the high voltage conductor forms a bottom connection arranged to connect with a first electrical device, which in the case of a transformer will be an internal component of the transformer. For this purpose, matching inner connections are provided in the transformer. At the upper end of the bushing, opposite the bottom connection end, the conductor is provided with an upper external terminal or external connection joint, by which the conductor is connected to a second electrical device or external source. Typically, in order to electrically connect the conductors and thus the transformer to an external source or electrical device, an external connection nipple is electrically connected to the conductors through a substantially flat interface, which at the same time forms the top cover of the bushing.

In another type of prior art bushing, the outer terminal cannot be attached directly to the top cover of the bushing, and the connection between the outer terminal and the conductor is made through an electrically conductive intermediate portion. This intermediate section is mounted on the end of the conductor, extending through the top cover of the bushing, and the outer terminals are screwed onto the intermediate section on the outside of the bushing. In order to fasten the middle section to the conductor, it must be screwed into a steel draw ring or similar located on the inside of the conductor. This drawing ring is in turn screwed into the conductor, so that the wall thickness of the conductor is reduced due to the necessary internal thread. This draw ring arrangement is also required to provide a seal.

The term high voltage is generally used for voltages above about 50 kilovolts. Today, commercial high voltage installations typically have an upper limit of 1100 kV, but voltages such as 1200 kV or even higher are foreseen in the near future. At the same time, current levels are also growing and can be as high as 4000-5000A or even higher.

For high voltages in the range of 800 kV and higher and rated currents of 2000 A and higher, the demands placed on bushings naturally increase – for example when faced with heat dissipation and cooling, electric fields, electrical insulation of bushings, etc. In this regard, low loss, especially the ability to achieve the target current becomes essential. The losses of current bushings are mainly due to the losses of the conductors and losses in the joints or contacts in the circuit between the different parts of the bushing. Thus, when considering conductors, it is increasingly important to minimize each device so that the conductive material in the conductor, such as threads, is reduced. It is also recognized that fewer splices reduce losses, which is beneficial in high voltage and high current applications.

Contents of the invention

An object of the present invention is to provide a high voltage bushing joint which improves the existing bushing joint and can achieve the above high voltage level and high rated current.

Another object of the present invention is to provide a high voltage bushing comprising such a joint and a high voltage device comprising such a bushing.

These and other objects are achieved by a high voltage bushing joint, a high voltage bushing and a high voltage device as defined in the independent claims.

Correspondingly, a high-voltage bushing joint is defined, which includes a first joint part for connecting with an electrical device and a second joint part for connecting with a conductor of the bushing, wherein the second joint part has an inner hole, the inner hole is provided with an opening for receiving the end of the conductor, characterized in that the joint also includes a set of mounting holes and a set of mounting members adapted to pass through the mounting holes, two The joint parts are fixed to the ends of the conductors through the mounting holes and mounting members, and each of the mounting holes has a first opening inside the inner hole of the second joint part. By using the same set of mounting holes and mounting screws to fix the two joint parts to the ends of the conductors, the advantage of a simpler construction with fewer parts is achieved.

According to another feature, said first joint part has a maximum external cross-sectional dimension perpendicular to the axis of said conductor, said mounting hole being located within said maximum external cross-sectional dimension of said first joint part. By positioning the mounting hole in accordance with this feature, the possibility is provided to give the first outer joint part a larger cross-section than in the prior art, for example when the mounting hole is located on the flange on the outside of the joint part. The larger diameter of the outer contact portion makes it possible to increase the current capacity without the need to manufacture bulky top contacts.

According to the first embodiment, the first joint portion is hollow, and each of the mounting holes has a second opening for inserting the mounting member inside the hollow portion of the first joint portion. . Thereby, the mounting member can be inserted into the mounting hole from the hollow interior of the first joint part, that is, the joint part is connected to an external electric device. With this arrangement, the mounting hole and the mounting member can be made shorter than in the second embodiment described below.

According to a second embodiment, the first joint part is a solid body, and each mounting hole extends through the solid body and further through the bottom of the inner hole. This embodiment is simple and robust to manufacture.

In this embodiment, each mounting hole has a second opening at the free end of said first joint part.

According to another feature of the joint according to the invention, the joint is made in one piece. This provides for example an advantageous current path with minimal splice losses. It is also easy to manufacture. For example, it can be manufactured by lathing a solid bar stock or using a tube stock.

In a variation of the first embodiment, the inner hole of the second joint part may be separated from the hollow part of the first joint part by an isolating intermediate wall, and the mounting hole is formed in the intermediate wall.

According to the present invention, a high-voltage bushing including the external connection joint as described in any claim defining the joint, and a high-voltage device including such a high-voltage bushing are also defined.

Description of drawings

The invention will now be described with reference to the accompanying drawings, which show embodiments of the invention, by way of example only, in which:

The sectional view of Fig. 1 schematically shows that one end of the high voltage bushing is provided with an external connection joint according to the first embodiment of the present invention;

Figure 2 is an enlarged sectional perspective view schematically showing a joint according to a first embodiment of the invention;

Figure 3 is a cross-sectional view schematically showing a variant of the first embodiment of the joint; and

FIG. 4 schematically shows a second embodiment of the joint according to the invention in a sectional view.

Detailed ways

One end of a high voltage bushing provided with a joint according to a first embodiment of the invention is shown in FIG. 1 . The high voltage bushing comprises a hollow bushing insulator 2 which forms a jacket around the high voltage conductor 10 . The ends of the casing are closed by a top cover 4 . The cover is provided with a hole 6 through which a conductor 10 extends to the outside of the bushing. An example of such an arrangement is described in the European patent application entitled "High voltage bushing and high voltage device comprising the same", filed on the same date as the present application by the same applicant.

The conductor 10 is hollow and provided at its ends with some type of end plug 12, which is only schematically shown. There may also be other means or arrangements not shown inside the conductor - such as tie rod arrangements. Alternatively, the conductors may be solid, in which case the joints may be attached to the conductors by screws 24 screwed into corresponding mounting holes provided at the ends of the conductors.

The joint according to the first embodiment shown in FIGS. 1 and 2 comprises a first joint part 14 for connecting an electrical device outside the bushing and a second joint part 16 for connecting a conductor 10 . For this purpose, the second connection part has an inner bore 18 provided with an opening for receiving the conductor 10 . The ends of the conductors are inserted into said bores and the electrical connection to the connector is ensured by electrical connection means 20 (electrical connection means not shown in FIG. 2 ). The joint also includes mounting holes 22 and mounting members 24, such as screws in the example, through which the joint is secured to the ends of the conductors. Having a first joint part and a second joint part ensures a redundant electrical connection between the conductor 10 and the joint 14, and if one joint part fails the other joint part is sufficient to transfer current from the conductor to the joint.

In the illustrated embodiment, the first joint part 14 , also referred to below as the outer joint part, is hollow. The second connection part 16 , which is also referred to below as a conductor connection part, has a bottom part formed by the bottom of the inner hole 18 . This bottom part can also be described as an intermediate wall 26 separating the outer connection part from the conductor connection part. In the illustrated embodiment, the outer terminal part 14, the conductor terminal part 16 and the intermediate wall 26 are formed in one piece.

The mounting hole 22 is formed in the intermediate wall 26 and forms an opening in the hollow interior of the outer terminal part 14 and an opening in the inner bore 18 of the conductor terminal part 16 . When the connector is mounted on the conductor, the screw 24 is inserted into the hole 22 and screwed into the end of the conductor provided with specific suitable means for receiving the screw. It could be a simple end plug or other suitable means.

FIG. 3 shows a variant of the first embodiment. In this figure, elements that are the same as or similar to those in FIGS. 1 and 2 are given the same reference numerals. The joint according to this variant comprises an outer joint part 14 and a conductor joint part 16 with an inner bore 18 . The outer joint is hollow. This variant differs from FIG. 2 in that the intermediate wall 36 is made as a separate element inserted into the joint. Thus, mounting holes 22 are made in this separate element.

Fig. 4 shows a second embodiment of the present invention. According to this embodiment, the outer joint 14 is not hollow, but is made as a solid body. The mounting hole 42 runs through the entire solid body 14 , extending from the free outer end of the outer joint part 14 to the inner hole 18 inside the conductor joint part 16 .

Both the outer shape and the inner shape of the outer joint portion 14 may vary. In Fig. 2, the outer joint portion is shown as cylindrical. However, it is also quite possible to be square, hexagonal or any other shape that fits the connectors of the electrical device to which it will be connected. For example, in the case of the second embodiment a hexagonal shape may be suitable.

In all embodiments, the first (outer) joint part has a largest outer cross-sectional dimension perpendicular to the conductor axis, and the mounting hole is located within the largest outer cross-sectional dimension of this first joint part. This is independent of the outer or inner shape of the outer joint.

In this specification, the term "high voltage (HV)" is used for voltages of 50 kilovolts and higher. The upper limit of the current commercial high voltage is 1100 kV, but it is foreseeable that the present invention can also be used for higher voltages, up to 1200 kV or even higher. Generally, the present invention is suitable for high voltages of about 200 kilovolts and above.

The high-voltage bushing joint can be used in bushings in DC or AC applications.

The joints and high voltage bushings of the present invention can also be used in many types of high voltage devices - such as transformers, reactors, circuit breakers, generators, switchgear or any other suitable device used in high voltage systems. Furthermore, in the context of the present invention, the terms "electrical device" and "high voltage device" are understood to include cables, busbars, surge arresters, DC valves and the like.

In addition, the invention does not impose restrictions on the media on each side of the bushing, such as air-oil, air-air (through-wall bushing), air-gas (gas switch), etc. The choice of insulating medium inside the bushing is also not limited. It may for example be gas, oil, gel or a combination thereof.

The invention is not limited to the embodiments given as examples only, but it can be varied and modified in many ways within the scope of the appended claims as is appreciated by a person skilled in the art.

Claims (5)

1. A high-voltage bushing joint, comprising a first joint part (14) for connecting with an external electrical device, that is, an outer joint part and a second joint part (16) for connecting with a conductor (10) of the bushing ), wherein the second joint part has an inner hole (18), and the inner hole is provided with an opening for accommodating the end of the conductor, and it is characterized in that the high-voltage bushing joint also includes a set of mounting holes ( 22, 42) and a set of mounting members (24) adapted to pass through the mounting holes, the two joint parts (14, 16) are fixed to the conductor (10) through the mounting holes and mounting members Each of the mounting holes (22, 42) has a first opening located inside the inner hole (18) of the second joint part (16), and the first joint part (14 ) is hollow, and each of the mounting holes (22) has a second opening for inserting the mounting member (24) inside the hollow portion of the first joint portion. 2. The high-voltage bushing joint according to claim 1, characterized in that, the first joint part and the second joint part are made in one piece. 3. The high-voltage bushing joint according to claim 1, characterized in that, the inner hole (18) of the second joint part (16) and the hollow part of the first joint part are separated by an intermediate wall (36) spaced apart, and the mounting holes (22) are formed in the intermediate wall. 4. A high-voltage bushing, comprising the high-voltage bushing joint according to any one of claims 1 to 3. 5. A high voltage device comprising the high voltage bushing as claimed in claim 4.

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