Patent Publication Number: US-2005121418-A1

Title: Gas-insulated switchgear

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a gas-insulated switchgear in which electrical components are accommodated in a hermetically sealed container filled with insulating gas and, more particularly, to gas sealing thereof.  
      2. Description of the Related Art  
      In a conventional gas-insulated switchgear provided with a hermetically sealed container, in which switching unit or electrical components such as circuit breaker, disconnector, grounding switch, load switch or the like are accommodated, a gas seal groove is provided on any of one hermetically sealed container, another hermetically sealed container, a flange, a bushing and so on. Further, a gas-sealing member such as packing or O-ring is disposed in the gas seal groove, thus forming an airtight connection (see the Japanese Utility Model publication (unexamined) No. 1981-114587, for example).  
      In the conventional gas-insulated switchgear, since a gas seal groove is used, it is essential that the hermetically sealed container, flange, bushing or the like be provided with a plate of sufficient thickness. As a result, a problem exists in that the hermetically sealed container, flange, bushing or the like increases in weight as well as in cost due to complexity in processing the gas seal groove.  
     SUMMARY OF THE INVENTION  
      The present invention was made to solve the above-discussed problems and has an object of obtaining a gas-insulated switchgear in which a hermetically sealed container, flange, bushing or the like is light in weight, and processing of the hermetically sealed container, flange, or bushing is easy, eventually resulting in cost saving.  
      A gas-insulated switchgear according to the invention includes a hermetically sealed container filled with insulating gas and in which electrical components are accommodated. In this gas-insulated switchgear, a gas-sealing member that surrounds an opening of the mentioned hermetically sealed container and is brought into airtight contact with periphery of the mentioned opening is disposed between the periphery of the opening of the mentioned hermetically sealed container and a member air-tightly connected to the periphery of the opening. Further, an outer gas seal guide that holds the mentioned gas-sealing member surrounding outer circumference of the mentioned gas-sealing member, and brings the mentioned gas-sealing member into contact with the periphery of the mentioned opening, is also disposed between the periphery of the opening of the mentioned hermetically sealed container and the member air-tightly connected to the periphery of the opening. Furthermore, an inner gas seal guide that holds the mentioned gas-sealing member along inner circumference of the mentioned gas-sealing member and brings the mentioned gas-sealing member into contact with the periphery of the mentioned opening, is also disposed between the periphery of the opening of the mentioned hermetically sealed container and the member air-tightly connected to the periphery of the opening. Thus, airtight connection is established between periphery of the opening of the mentioned hermetically sealed container and the mentioned member air-tightly connected to the periphery of the opening.  
      In the gas-insulated switchgear of above construction according to the invention, it is not necessary to provide any groove of the gas-sealing member on the periphery of the opening of the hermetically sealed container or on the member air-tightly connected to the periphery of the opening, eventually resulting in easy processing and cost saving.  
      Another gas-insulated switchgear according to the invention also includes a hermetically sealed container filled with insulating gas and in which electrical components are accommodated. In this gas-insulated switchgear, a gas-sealing member that surrounds an opening of the mentioned hermetically sealed container and is brought into airtight contact with periphery of the mentioned opening is disposed between the periphery of the opening of the mentioned hermetically sealed container and a member air-tightly connected to the periphery of the opening. Further, an outer gas seal guide that is held with a bolt that is provided on either the periphery of the mentioned opening or a member air-tightly connected to provide a connection between them, holds the mentioned gas-sealing member surrounding outer circumference of the mentioned gas-sealing member, and brings the mentioned gas-sealing member into contact with the periphery of the mentioned opening is disposed between the periphery of the opening of the mentioned hermetically sealed container and a member air-tightly connected to the periphery of the opening. Furthermore, an inner gas seal guide that holds the mentioned gas-sealing member along inner circumference of the mentioned gas-sealing member and brings the mentioned gas-sealing member into contact with the periphery of the mentioned opening is also disposed between the periphery of the opening of the mentioned hermetically sealed container and the member air-tightly connected to the periphery of the opening. Thus, airtight connection is secured between periphery of the opening of the mentioned hermetically sealed container and the mentioned member air-tightly connected to the periphery of the opening.  
      In the gas-insulated switchgear of above construction according to the invention, the outer gas seal guide that surrounds the outer circumference of the gas-sealing member and brings the gas-sealing member into contact with the periphery of the opening is held with the bolt that is provided on either the periphery of the mentioned opening or on the mentioned member air-tightly connected to connect the periphery and the member. As a result, work efficiency is improved and the gas-sealing member can be stably held.  
      The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a sectional view showing a gas-insulated switchgear according to Embodiment  1  of the present invention.  
       FIG. 2  is an exploded perspective view showing a portion where a gas-sealing flange is mounted in an opening of a hermetically sealed container of the gas-insulated switchgear in  FIG. 1 .  
       FIG. 3  is a perspective view showing the portion of  FIG. 2  where the gas-sealing flange is mounted.  
       FIG. 4  is an enlarged sectional view of a gas-sealing flange gas seal portion showing an essential part of Embodiment 1.  
       FIG. 5  is an enlarged sectional view of a gas-sealing vessel gas seal portion showing an essential part of Embodiment 2. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Embodiment 1  
      Referring now to  FIG. 1  being a sectional view showing a gas-insulated switchgear according to Embodiment 1 of this invention, a hermetically sealed container  2 , which is hermetically sealed and filled with insulating gas such as SF 6  gas, is supported on a stand  1 . The hermetically sealed container  2  includes a cylindrical shell plate part  3 , a top plate part  4  covering an opening at the top of the shell plate part  3 , a bottom plate part  5  covering an opening at the bottom of the shell plate part  3 , and a gas-sealing flange  19  covering an opening  5   b  of the bottom plate part  5 . The bottom plate part  5  is provided with a protrusion  5   a  protruding downward so as to extend the internal space of the hermetically sealed container  2 . Plural stud bolts  5   c  are welded to the periphery of the opening  5   b  of the protrusion  5   a.    
      The shell plate part  3  also includes a front shell plate part  6  and a gas-sealing flange  7  fixed to this front shell plate part  6 . The front shell plate part  6  is provided with an opening  6   a , and plural stud bolts  6   a  are welded to the periphery of this opening  6   a . The top plate part  4 A is provided with a three-phase bus bar bushing  8 . A bus bar connector  9  is connected to the bus bar bushing  8 A. The protrusion  5   a  A is provided with a cable bushing  10 . A cable  11  is connected to the cable bushing  10 .  
      A circuit breaker  12  for electrically connecting and disconnecting the circuit between the bus bar connector  9  and the cable  11  is accommodated in the hermetically sealed container  2 . The circuit breaker  12  is held in an insulating holder  13  fixed to the gas-sealing flange  7  and has a vacuum valve  14  acting as an arc-extinguishing chamber of the circuit breaker. Further, a disconnector/grounding switch  15  for connecting, disconnecting, and grounding the circuit between the circuit breaker  12  and the bus bar connector  9  is accommodated in the hermetically sealed container  2 . A panel  16  is fixed to a front face of the hermetically sealed container  2 . The panel  16  is fixed to the hermetically sealed container  2  utilizing the stud bolts  6   b  for fixing the gas-sealing flange  7  or utilizing stud bolts (not shown in the drawing) welded to the front face of the hermetically sealed container  2  and used exclusively for fixing the panel.  
      A circuit breaker operating mechanism  17 , a disconnector/grounding switch operating mechanism  18 , and a control unit (not shown) are accommodated in the panel  16 . The circuit breaker operating mechanism  17  and the disconnector/grounding switch operating mechanism  18  are mounted on the gas-sealing flange  7  utilizing plural stud bolts welded to the gas-sealing flange  7 . In addition, it is general that switching apparatus or electrical components such as circuit breaker, disconnector, grounding switch, and a load switch are accommodated in the hermetically sealed container of the gas-insulated switchgear.  
       FIG. 2  is an exploded perspective view showing a portion where the gas-sealing flange is mounted in the opening of the hermetically sealed container of the gas-insulated switchgear in  FIG. 1 , and  FIG. 3  is a perspective view showing the portion of  FIG. 2  where the gas-sealing flange is mounted. Referring to  FIGS. 2 and 3 , the plural stud bolts  5   c  are welded to the periphery of the opening  5   b  disposed on the protrusion  5   a  of the bottom plate part  5  of the hermetically sealed container  2 . Reference numeral  22  is a gas-sealing member such as n O-ring or packing made of rubber. The gas-sealing member  22  surrounds the opening  5   b  of the hermetically sealed container  2  and is brought into contact with the periphery of the opening  5   b.    
      An outer gas seal guide  20  holds the gas-sealing member  22  surrounding the outer circumference of the gas-sealing member  22  and brings the gas-sealing member  22  into contact with the periphery of the opening  5   b  of the hermetically sealed container  2 . The outer gas seal guide  20  is provided with through holes  20   a  corresponding to the position of the plural stud bolts  5   c . By passing the stud bolts  5   c  through the through holes  20   a , the outer gas seal guide  20  is positioned and held by the stud bolts  5   c . An inner gas seal guide  21  holds the gas-sealing member  22  along the inner circumference of the gas-sealing member  22  and brings the gas-sealing member  22  into contact with the periphery of the opening  5   b  of the hermetically sealed container  2 . In this manner, the gas-sealing member  22  is held by the outer gas seal guide  20  from outer circumference side, held by the inner gas seal guide  21  from inner circumference side, and brought into contact with the periphery of the opening  5   b  of the hermetically sealed container  2 . The outer gas seal guide  20  and the inner gas seal guide  21  are made of an iron material such as stainless steel.  
      The gas-sealing member  22 , the outer gas seal guide  20  and the inner gas seal guide  21  are held between the gas-sealing flange  19  and the periphery of the opening  5   b  of the hermetically sealed container  2 , and plural washers  23  and plural nuts  24  are used to fix the gas-sealing flange l 9  on the plural studbolts  5   c , thus achieving an airtight connection to the hermetically sealed container  2 . In addition, it is also preferable to use another hermetically sealed container, any bushing or the like as the member airtightly connected to the periphery of the opening  5   b  of the hermetically sealed container  2 , instead of the flange.  
       FIG. 4  is an enlarged sectional view of the gas-sealing flange gas seal portion showing an essential part of Embodiment 1. The stud bolt  5   c  is welded to the periphery of the opening  5   b  formed on the protrusion  5   a  of the bottom plate part of the hermetically sealed container  2 . Numeral  30  is an internal part of the hermetically sealed container  2 . The outer circumference of the gas-sealing member  22  is surrounded by and held on the outer gas seal guide  20 . The outer gas seal guide  20  is positioned and held by inserting the stud bolt  5   c  in the through holes of the outer gas seal guide  20 . The inner gas seal guide  21  holds the gas-sealing member  22  along the inner circumference of the gas-sealing member  22 . The stud bolt  5   c  is inserted in through holes  19   a  provided at a position corresponding to the stud bolts  5   c , and the gas-sealing member  22 , the outer gas seal guide  20  and the inner gas seal guide  21  are held between the gas-sealing flange  19  and the periphery of the opening  5   b  of the hermetically sealed container  2 , and the plural washers  23  and plural nuts  24  are used to fix the gas-sealing flange  19  to the plural stud bolts  5   c , thus the gas-sealing flange  19  being air-tightly connected to the hermetically sealed container  2 . In addition, the gas-sealing flange  19  acts as a member air-tightly connected to the periphery of the opening  5   b  of the hermetically sealed container  2 . Although the outer gas seal guide  20  is positioned and held by inserting the stud bolts  5   c  in the through holes, it is also preferable to position and hold the inner gas seal guide  21  by providing through holes through the inner gas seal guide  21 , instead of the outer gas seal guide  20 , and inserting the stud bolts  5   c  in the through holes in the same manner. It is also preferable to weld the stud bolts  5   c  to the gas-sealing flange  19  side and provide through holes for the stud bolts  5   c  on the hermetically sealed container  2  side, instead of welding the stud bolts  5   c  to the hermetically sealed container  2 .  
      In the gas-insulated switchgear described above, the gas-sealing member such as packing or O-ring is held between the periphery of the opening of the hermetically sealed container and the gas-sealing flange by disposing the outer gas seal guide and the inner gas seal guide respectively on the outer and inner circumferences of the gas-sealing member without use of any gas seal groove, thus achieving an airtight connection between them. As a result, processing of the gas-insulated switchgear is easy and cost thereof is reduced. Since the outer gas seal guide is positioned by the stud bolts, work efficiency is improved and the gas-sealing member is stably held.  
     Embodiment 2  
       FIG. 5  is an enlarged sectional view of a gas-sealing vessel gas seal portion showing an essential part of Embodiment 2. In the drawing, the same numerals indicate the same or like parts. Referring to  FIG. 5 , ends of a first hermetically sealed container  25  and a second hermetically sealed container  26  facing each other are bent to be formed into L-shaped portions  25   a  and  26   a  respectively, and ends of the L-shaped portions  25   a  and  26   a  are provided with through holes  25   b  and  26   b  for fastening with a bolt. Numeral  31  is an internal part of the hermetically sealed container. The L-shaped portion  25   a  of the first hermetically sealed container  25  serves as the periphery of the opening of the hermetically sealed container. The L-shaped portion  26   a  of the second hermetically sealed container  26  serves as the member airtightly connected to the periphery of the opening. The outer gas seal guide  20  is surrounded and held by the gas-sealing member  22  at the outer circumference thereof. A bolt  27  regulates the position of the outer circumference of the outer gas seal guide  20  and holds the outer gas seal guide  20 . The inner gas seal guide  21  holds the gas-sealing member  22  along the inner circumference of the gas-sealing member  22 .  
      The gas-sealing member  22 , and the outer gas seal guide  20  holding the outer circumference side and the inner gas seal guide  21  holding the inner circumference side are positioned by the bolt  27  passing through the through holes  25   b  and  26   b  and are held between the L-shaped portion  25   a  of the first hermetically sealed container  25  and the L-shaped portion  26   a  of the second hermetically sealed container  26 . The L-shaped portion  25   a  of the first hermetically sealed container  25  and the L-shaped portion  26   a  of the second hermetically sealed container  26  are fixed with the bolt  27 , washers  23   a  and  23   b  and nuts  24 , thus an airtight connection being provided between them.  
      In the gas-insulated switchgear described above, the gas-sealing member such as packing or O-ring is held between the periphery of the opening of the hermetically sealed container and the periphery of the opening of the other hermetically sealed container by disposing the outer gas seal guide and the inner gas seal guide respectively on the outer and inner circumferences of the gas-sealing member without use of any gas seal groove, thus achieving an airtight connection between them. As a result, processing of the gas-insulated switchgear is easy and cost thereof is reduced. Since the outer gas seal guide is positioned by the stud bolts, work efficiency is improved and the gas-sealing member is stably held.  
     Embodiment 3  
      In this invention, it is unnecessary to form any gas seal groove for a gas-sealing member on the hermetically sealed container or a member air-tightly connected to the hermetically sealed container, and therefore it possible to reduce thickness of the plate of the hermetically sealed container or the member air-tightly connected to the hermetically sealed container. Accordingly, it is preferable to form the hermetically sealed container or the member airtightly connected to the hermetically sealed container employing a thin plate of not more than 6 mm in thickness. Any thin plate of such thickness is enough to form a gas seal groove and easily pressed. As a result, it is possible to reduce weight and save the cost.  
      This invention makes it possible to reduce thickness of the plate forming the heavy hermetically sealed container, and is therefore applicable to gas-insulated switchgears of various insulating gases, gas pressures and rated voltages, and it is possible to reduce weight and save the cost.  
      While the presently preferred embodiments of the present invention have been shown and described, it is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.