WO2010111808A1

WO2010111808A1 - Bushing for connecting gas insulated switchgear with air insulated switchgear

Info

Publication number: WO2010111808A1
Application number: PCT/CN2009/000367
Authority: WO
Inventors: Jianbo Xie; Xianbo Deng; Gunn-Kristin Sonsteby
Original assignee: Abb Technology Ltd.
Priority date: 2009-04-03
Filing date: 2009-04-03
Publication date: 2010-10-07
Also published as: EP2415133A4; CN102388514A; CN102388514B; EP2415133A1

Abstract

A bushing for connecting GIS with AIS. The bushing comprises a busbar (61) and a shield (62). The busbar and the shield are embedded in an electrically insulating body (64). The GIS-side of electrically insulating body is conical and the AIS-side of electrically insulating body is hollow. The electrically insulating body comprises an assembling flange (643) between the conical side (641) and the hollow side (642). On the hollow side, a number of sheds (644) are evenly distributed on the exterior. The angle formed by the axis from the center of the assembling flange to the end of conical side and the axis from the center of the assembling flange to the end of the hollow side is less than 180°.

Description

Bushing for Connecting Gas Insulated Switchgear with Air Insulated Switchgear

FIELD OF THE INVENTION

This invention relates to the field of power products, and more particularly to connection device between Gas Insulated Switchgear and Air Insulated Switchgear.

BACKGROUND OF THE INVENTION

There are usually two kind of insulation for high voltage switchgears, one is Air Insulated Switchgear (AIS), and the other is Gas Insulated Switchgear (GIS). GIS contains an insulating gas such as SF6. The insulation resistance between air and SF6 varied widely. Many high-voltage switchgears, such as 40.5 kV series switchgears, include GIS and AIS. The gas pressure of GIS is 1.4 bar, so the distance between two power phases can be less than 100mm. However, the distance between two power phases should be more than 300mm in AIS. When the two kinds of switchgears are used in the substation simultaneously, a kind of connection between GIS and AIS is needed to meet the insulation requirements of the two switchgears.

EP1160945A1 discloses a gas-insulated switchgear comprises cable bushing. This kind of cable bushing is widely used as connection device in switchgears. Fig.iA to Fig.1C shows the connection device. It contains: feeder bushing 3, cable 1 and cable termination 2. The feeder bushing 3 is embedded in the side plate of GIS with one end in GIS and the other in AIS. The feeder bushing is pressurized with the GIS side plate by seal ring. Fig.1C shows the connection device with the side in AIS seal connected with cable by cable termination 2. The solid insulation of cable 1 and cable termination 2 can meet the insulation resistance requirement of AIS.

The connection device described above is widely used in some regions, such as Europe, but it has some disadvantages: 1) It needs more space in AIS for using cable connecting, because cable bending radius is too long. In general, the bending radius is about ten to fifteen times of the cable diameter, which makes the size of switchgear very big. As the cable needs to be bended, it takes up too much space. Therefore, this connection device can't meet the market demand in some regions.

2) 40.5 kV cable terminations are very expensive. So it makes the connection device high cost.

SUMMARY OF THE INVENTION

To overcome above shortcomings, a much cheaper connection device is provided by the present invention. According to the present invention, it does not use cable to connect, so the size of AIS can be reduced.

According to the present invention, a bushing for connecting GIS with AIS is provided; said bushing comprises busbar and shield; the busbar and shield are embedded in an electrically insulating body; the GIS-side of the electrically insulating body is conical and AlS-side of electrically insulating body is hollow; the electrically insulating body further comprises an assembling flange which is between said conical side and said hollow side; on said hollow side, a number of sheds are evenly distributed on the exterior.

The hollow side of the insulating body encloses a cavity adapted to accommodate an insulating busbar for connecting the busbar to AIS, wherein the diameter of the cavity is decreasing towards the busbar.

According to one preferred embodiment of the invention, the electrically insulating body is made of epoxy resin. The shield is like a tube and at one point of the circumference, there is a column conductor as a joint, said joint is for earthing; said shield surrounding busbar and embedded in assembling flange.

In a preferred embodiment, a fixing profile, made of insulated material and used for fixing an insulated busbar connected to the busbar, can be attached to the end of the hollow side. And there are two inset nuts on end of the hollow side to tightly fix the fixing profile by screws.

According to one preferred embodiment of the invention, the busbar is circular with a screw on both ends for connecting to the insulated busbar or electrical devices. And the busbar further connects a tulip contact.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention will be explained in more details in the following description with reference to preferred exemplary embodiments which are illustrated in the drawings, in which:

Fig. 1Ato Fig. 1C shows the connection device or the prior art; in which Fig. 1A shows the bushing, Fig. 1 B shows the cable and the cable termination, Fig. 1C shows the assembling of the prior connection device;

Fig. 2Ato Fig.2C shows the structure of the bushing of present invention, in which, Fig.2A shows the appearance and structure of the bushing; Fig. 2B is a section view of the bushing; Fig. 2C shows the structure of shield; Fig. 2D is a side view of the bushing with inset nuts on the end;

Fig. 3Ato Fig. 3E shows the bushing and other connection components, in which, Fig. 3A shows the structure of fixing profile; Fig. 3B shows the insulated busbar being fixed on the right end of the bushing by fixing profile; Fig. 3C shows the bushing connected to the insulated busbar; Fig. 3D is a magnifying view of the tulip contact; Fig. 3E shows the structure of insulated busbar;

Fig. 4A to Fig. 4B shows the bushing connected GIS with AIS; the bushing further connected with a tulip contact according to an embodiment of the invention; in which, Fig. 4A shows the bushing after assembling; Fig. 4B is a section view of the bushing after assembling; Fig. 4C is GIS side view of the bushing;

Fig. 5Ato Fig. 5B shows the simulation results. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig.2A shows the appearance and the structure of the bushing; Fig. 2B is a section view of the bushing according to a preferred embodiment. The bushing

6 comprises busbar 61 and shield 62, the busbar 61 and shield 62 are embedded in an electrically insulating body 64 which is made of epoxy resin; the left side of electrically insulating body 64 is conical and connected to GIS.

The right side of electrically insulating body 64 is hollow and connected to AIS.

The electrically insulating body 64 further comprises an assembling flange 643 between conical side 641 and hollow side 642. There are sheds 644 evenly distributed on the exterior of the hollow side 642.

The hollow side of the insulating body encloses a cavity adapted to accommodate an insulating busbar 8 for connecting the busbar 61 to AIS, wherein a diameter of the cavity is decreasing towards the busbar 61. The angle formed by the axis from the center of the assembling flange 643 to the end of conical side 641 and axis from the center of the assembling flange 643 to the end of the hollow side 642 is varied according to different kinds of AIS. According to the AIS in an embodiment of the present invention, the angle is larger than 120° and less than 180°, and preferably equal to 170°.

Fig. 2C shows the structure of electromagnetic shield. As shown in the drawing, the electromagnetic shield 62 is like a tube; and at one point of the circumference, there is a column conductor as a joint which is for earthing. The shield 62 surrounds the busbar 61 , embedded in assembling flange 643 and coaxial with busbar 61 at the location of assembling flange 643. It is used for balancing electric strength and as the indicator for the presence of high voltage.

Fig. 2D is a side view of the bushing with inset nuts on the end; on the right end of the bushing 6 are two inset nuts 63 used to tightly fix the fixing profile 65 by screws 66. Fig. 3A shows the structure of fixing profile 65; the fixing profile 65, made of insulated material, is molded and used for fixing insulated busbar 8. Fig. 3B shows the insulated busbar being fixed on the right end of the bushing by fixing profile. The busbar 61 , shield 62 and inset nuts 63 are all molded in the epoxy resin.

Fig. 3C shows the bushing connected to the insulated busbar. On the left side of the bushing, the busbar 61 connects a tulip contact 7. As shown in Fig.3D, the port of the tulip contact 7 is made of six petal-shaped plates with a rounded spring 71 wrapped. When one side of busbar is inserted in the port, reliable connection between tulip connect 7 and busbar can be achieved relying on the force of said spring 71.

Fig. 3E shows the structure of insulated busbar 8, Insulated Busbar 8 is composed of conductive copper 81 and insulated outside layer 82. Said conductive copper 81 is tightly wrapped by said insulated outside layer 82, with two joint ends exposed.

Fig.4A to Fig.4B shows the bushing connected GIS with AIS. The left side of the bushing 6 is connected to GIS, and pressurize with the side plate by seal ring. Fig. 4C is GIS side view of the bushing; the seal slot 649 can be seen from Fig. 4C. The right side of the bushing 6 is connected to AIS. On this side, the port of tulip contact 7 is connected to busbar 61 by bolt in the hollow of the bushing 6. Reliable connection between tulip connect 7 and insulated busbar 8 can be achieved relying on the force of the spring 71. The insulated busbar 8 is fixed on the bushing 6 by the insert nuts 66 and insulated fixing profile 65. The bushing can withstand 50 kA peak value of short-circuit making current. The creeping distance in AIS is more than 800 mm. This distance is enough for creeping insulation. The rated current is 630 A.

Fig.5A to Fig.δB shows the simulation results done by professional software Pro/Engineer and Toolbox (Electric strength analysis software developed by ABB). In the simulation, the bolt and insert nuts are simplified, and the bushing and its surrounding assembling plate are analyzed.

Whether electric strength is equal within the bushing and whether can meet the requirements of insulated material are mainly analyzed. The busbar and insulated busbar are high voltage part, the shield and assembling plate are connected to the earth (zero potential), and analysis of the use of boundary conditions is the most severe, such as high voltage is added to 185 kV. The simulation result shows that the electric strength in the bushing is equally distributed and meets the requirements of the electric performance of connection devices.

Though the present invention has been described on the basis of some preferred embodiments, those skilled in the art should appreciate that those embodiments should by no means limit the scope of the present invention. Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims.

Claims

1. A bushing for connecting Gas Insulated Switchgear with Air Insulated Switchgear, comprising busbar (61) and shield (62), characterized in that said busbar (61) and shield (62) being embedded in an electrically insulating body (64); a GIS-side of electrically insulating body (64) being conical and an AlS-side of electrically insulating body (64) being hollow; the electrically insulating body (64) further comprising an assembling flange (643) being between said conical side (641) and said hollow side (642); on said hollow side (642), a number of sheds (644) being evenly distributed on the exterior.

2. The bushing according to claim 1 , characterized in that the hollow side of the insulating body encloses a cavity adapted to accommodate an insulating busbar (8) for connecting the busbar (61) to AIS, wherein a diameter of the cavity is decreasing towards the busbar (61).

3. The bushing according to claim 1 , characterized in that said electrically insulating body (64) is made of epoxy resin.

4. The bushing according to claim 1 , characterized in that said shield (62) is a tubular electromagnetic shield and surrounds the busbar (61) at the location of assembling flange (643).

5. The bushing according to claim 1 , characterized in that a fixing profile (65), made of insulated material and used for fixing an insulated busbar (8) connected to the busbar (61), can be attached to the end of the hollow side.

6. The bushing according to claim 5, characterized in that there are two inset nuts (63) on end of the hollow side (642) to tightly fix the fixing profile (65) by screws.

7. The bushing according to claim 1 , characterized in that an angle formed by the axis from the center of the assembling flange (643) to the end of conical side (641) and axis from the center of the assembling flange (643) to the end of the hollow side (642) is larger than 120° and less than 180°.

8. The bushing according to any one of the claims above, characterized in that said busbar (61) is circular with a screw on both ends for connecting to the insulated busbar (8) or electrical devices.

9. The bushing according to claim 8, characterized in that said busbar (61) connect a tulip contact (7).