Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B17/00—Insulators or insulating bodies characterised by their form
  • H01B17/26—Lead-in insulators; Lead-through insulators

Definitions

• the present invention relates to the field of high voltage power systems, and in particular to contacts for high voltage bushings used in high voltage devices forming parts of such systems.
• high voltage equipment and devices e.g. high voltage transformers, reactors, switchgear etc.
• bushings that are adapted for carrying current at high potential through a grounded barrier, e.g. a wall or an enclosure of the electric device, such as a transformer tank.
• Conventional high voltage bushings comprise an insulator made of ceramic or composite material, which is provided with sheds and which is generally hollow.
• voltage grading is performed by a condenser body or some other type of voltage grading device, through which an electrical conductor passes. The electrical conductor connects one side of the bushing, where a high voltage electric device is connected, with the other side of the bushing where another electric device is connected.
• the bushing when the first electric device is a transformer, the bushing is fitted on the transformer enclosure, such as the tank wall, and the conductor of the bushing connects the inside of the transformer with the outside, where another electric device can be connected, e.g. a bus, surge arrester or DC valve.
• the transformer enclosure such as the tank wall
• another electric device can be connected, e.g. a bus, surge arrester or DC valve.
• the bottom end portion of the high voltage conductor forms a bottom contact that is arranged to be connected to a first electric device, which in the case of a transformer will be the internal components of the transformer.
• a mating internal contact is provided inside the transformer.
• the conductor is provided with an upper outer terminal, or external connection contact, by means of which the conductor is connected to a second electric device or external source.
• the external connection contact is electrically connected to the conductor through an essentially planar interface, also forming a top cover of the bushing, in order to electrically connect the conductor and thus the transformer to an external source or electric device.
• high voltage is conventionally used for voltages above approximately 50 kV.
• the upper limit in commercial high voltage devices is generally 1100 kV, but higher voltages, such as 1200 kV or even more, are envisaged in the near future.
• current levels are increasing and may be up to 4000-5000 A or even higher.
• a high voltage bushing contact comprising a first contact part for connection with an electric device and a second contact part for connection with a conductor of the bushing, wherein the second contact part has an inner bore with an opening for receiving an end of the conductor, characterized in that the contact also comprises a set of mounting holes and a set of mounting members adapted to be inserted through the mounting holes and by means of which both contact parts are secured to the end of the conductor, and that each mounting hole has a first opening inside the inner bore of the second contact part.
• the first contact part has a maximum external cross sectional measure, perpendicular to the axis of the conductor, and the mounting holes are located within the maximum external cross sectional measure of the first contact part.
• the first contact part is hollow and each mounting hole has a second opening inside the hollow portion of the first contact part, for insertion of the mounting members.
• the mounting members can therefore be inserted into the mounting holes from inside the hollow interior of the first contact part, i.e. the contact part that is connected to an external electrical device.
• the mounting holes and the mounting members may be made shorter than in the second embodiment described below.
• the first contact part is a solid body and each mounting hole stretches through the solid body and further through a bottom of the inner bore. This embodiment is simple to manufacture and sturdy.
• each mounting hole has a second opening at a free end of the first contact part.
• the present invention is made in one piece. This provides for favourable current paths, with a minimum of losses due to joints, for example. It is also easy to manufacture. For example, it can be manufactured from a solid rod by using a lathe, or from a pipe.
• the inner bore of the second contact part may be separated from the hollow portion of the first contact part by a separate intermediate wall and the mounting holes are made in the intermediate wall.
• a high voltage bushing comprising an external connection contact in accordance with any one of the claims defining the contact, and a high voltage device comprising such a high voltage bushing.
• Fig. 1 illustrates schematically, in cross section, an end part of a high voltage bushing provided with an external connection contact in accordance with a first embodiment of the present invention
• Fig. 2 illustrates schematically, a perspective view in cross section and in a larger scale, the contact according to the first embodiment of the present invention
• Fig. 3 illustrates schematically, in cross section, a variant of the first embodiment of the contact
• Fig. 4 illustrates schematically, in cross section, a second embodiment of a contact according to the present invention.
• Fig. 1 is shown one end of a high voltage bushing provided with a contact according to a first embodiment of the present invention.
• the high voltage bushing comprises a hollow bushing insulator 2 that forms a housing around the high voltage conductor 10.
• the end of the bushing is closed by a top cover 4.
• the cover is provided with a hole 6 through which the conductor 10 runs 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 such bushing" which is filed on the same date as the present application and by the same applicant.
• the conductor 10 is hollow and it is provided with some kind of end plug 12 at its end, which end plug is only schematically illustrated. There may also be other devices or arrangement inside the conductor, such as a draw rod arrangement, which are not shown. Alternatively, the conductor may be solid, in which case the contact may be attached to the conductor by the screws 24 being screwed into corresponding mounting holes provided in the end of the conductor.
• the contact according to the first embodiment illustrated in Fig. 1 and Fig. 2 comprises a first contact part 14 for connection with an electric device outside the bushing, and a second contact part 16 for connection with the conductor 10.
• the second contact part has an inner bore 18 with an opening for receiving the conductor 10.
• the end of the conductor is inserted into the inner bore and electrical connection with the contact is ascertained by an electrical connection device 20 (electrical connection devices are not shown in fig 2).
• the contact also comprises mounting holes 22 and mounting members 24, such as screws in the illustrated example, by means of which the contact is secured to the end of the conductor.
• the arrangement with a first contact part and a second contact part ensures redundancy of electrical contact between conductor 10 and contact 14 and should one contact part fail the other is sufficient for carrying the currency from conductor to contact.
• the second contact part 16, also referred to as the conductor contact part in the following, has a bottom part, formed by the bottom of the inner bore 18. This bottom part can also be described as an intermediate wall 26 that separates the external contact part from the conductor contact part.
• the external contact part 14, the conductor contact part 16 and the intermediate wall 26 are all formed in one piece.
• the mounting holes 22 are formed in the intermediate wall 26, with one opening in the hollow interior of the external contact part 14 and one opening in inner bore 18 of the conductor contact part 16.
• FIG. 3 A variant of the first embodiment is shown in Fig. 3.
• the contact according to this variant comprises an external contact part 14 and conductor contact part 16 with an inner bore 18.
• the external contact part is hollow.
• the intermediate wall 38 is made as a separate element that is inserted in the contact. Consequently the mounting holes 22 are made in this separate element.
• FIG. 4 A second embodiment of the present invention is illustrated in Fig. 4.
• the external contact part 14 is not hollow, but is made as a solid body.
• the mounting holes 42 stretches all the way through the solid body
• the external shape as well as the internal shape of the external contact part 14 may vary.
• the external contact part is illustrated as being cylindric.
• a hexagonal shape may be suitable.
• the first, external, contact part has a maximum external cross sectional measure, perpendicular to the axis of the conductor, and the mounting holes are located within the maximum external cross sectional measure of the first contact part. This is irrespective of the external shape or internal shape of the external contact part.
• high voltage is used for voltages of 50 kV and higher.
• the present upper limit for commercial high voltage is 1100 kV, but it is foreseen that the invention can be used also for higher voltages, up to 1200 kV or even more. Generally, the present invention will find its applicability from about 200 kV and upwards.
• the described high voltage bushing contact may be used in a bushing both for DC and AC applications.
• inventive contact and high voltage bushing may also be used in many types of high voltage devices, such as transformers, reactors, breakers, generators, switchgear or any other suitable device finding an application in high voltage systems.
• electric device and high voltage device should also be interpreted as including cables, buses, surge arrestors, DC valves etc., within the context of the present invention.
• the present invention bears no restriction as concerns the media on the respective sides of the bushing, such as air-oil, air-air (wall bushing), air-gas (gas switchgear), etc. Nor does it involve any restriction as to the choice of insulation medium inside the bushing. It may for example be gas, oil, gel, or combinations thereof.

Landscapes

• Insulators (AREA)
• Gas-Insulated Switchgears (AREA)
• Coupling Device And Connection With Printed Circuit (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39760519

Family Applications (1)

Country Status (5)

Families Citing this family (1)

Citations (4)

Family Cites Families (4)

• 2008
  • 2008-05-06 AT AT08155694T patent/ATE521069T1/de not_active IP Right Cessation
  • 2008-05-06 EP EP08155694A patent/EP2117014B1/en active Active
  • 2008-06-19 CN CN200810127104.3A patent/CN101577375B/zh active Active
• 2009
  • 2009-04-07 WO PCT/EP2009/054158 patent/WO2009135743A1/en active Application Filing
  • 2009-04-07 BR BRPI0912526A patent/BRPI0912526A2/pt not_active IP Right Cessation

Patent Citations (4)

Also Published As

Similar Documents

Legal Events