Patent Publication Number: US-2020287362-A1

Title: Switchgear

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 2019-0025793, filed on Mar. 6, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates to a switchgear including an interlock device for a vacuum circuit breaker, which has an improved structure. 
     2. Discussion of Related Art 
     In an industrial site such as a power plant or a substation, a switchgear is installed for various purposes such as operation or control of electric power, operation of an electric motor, and the like, and various electronic devices including a circuit breaker may be disposed inside the above-mentioned switchgear. 
     Here, a vacuum circuit breaker is a kind of circuit breaker that is installed in a high voltage power system and configured to protect the electrical power system by interrupting a circuit when dangerous situations such as a short circuit or over current occur, and such a vacuum circuit breaker is designed employing properties such as excellent insulation performance and arc extinction capability in a vacuum state. 
     In addition to the function of accommodating components, the switchgear accommodating the vacuum circuit breaker should have a function to ensure safety when an accident occurs, and thus, except for special cases, in a state in which a door of the switchgear is opened, an insertion or withdrawal of the vacuum circuit breaker should not be permitted. 
     Therefore, the switchgear includes an interlock device for the vacuum circuit breaker. 
       FIG. 1  is a perspective view of a conventional switchgear, and  FIG. 2  is a view illustrating a conventional interlock device. 
     Referring to  FIGS. 1 and 2 , a switchgear  10  is a cabinet  11  of a substantially regular hexahedron having an opened front side, and a door  12  is hinge-fastened to one side of the cabinet to open and close the front side of the switchgear  10 . 
     A vacuum circuit breaker may be movably disposed inside the switchgear  10 , and the vacuum circuit breaker may include a circuit breaker main body  13  and a transfer part  14 . 
     The transfer part  14  includes a structure disposed below the circuit breaker main body  13  to move the circuit breaker main body  13  forward and rearward in the switchgear  10 . 
     Specifically, the transfer part  14  includes a carriage  15  disposed below the circuit breaker main body  13  and a lead screw  16  configured to move the carriage  15 . In addition, the lead screw  16  is forwardly or reversely rotated by manipulation of a manipulating handle  1  (see  FIG. 3 ) entering the switchgear  10  from the outside of the door  12  to move the circuit breaker main body  13  forward or rearward. 
     In a general state, an angular rotation preventing part is disposed on an outer circumferential surface of the lead screw  16 , and the lead screw is disposed such that the rotation preventing part is inserted into a rotation preventing groove formed at a push block  19 , and thus rotation of the lead screw is limited. 
     In addition, the push block  19  should be moved rearward to be spaced apart from the rotation preventing groove, and this movement is restricted by supporting a rear side of the push block  19  using an interlock protrusion  17   a  of an interlock device  17 . 
     In this state, in order to rotate the lead screw  16 , a safety structure must be released in two stages. 
     Firstly, a lever  18  disposed on an inner side surface of the door  12  in a protruding manner should enter the interlock device  17  disposed above the push block  19 , and the interlock protrusion  17   a  in the interlock device  17  is thus moved upward to be spaced apart from the push block  19 . 
     Secondly, when the manipulating handle  1  enters from the outside of the door  12  into the insider, is inserted into a front portion of the lead screw  16 , and then presses the lead screw rearward, the push block  19  which fixes the lead screw  16  is pushed rearward, and as a result, the push block is spaced apart from the lead screw  16 . 
     The conventional switchgear  10  has the following problems. 
     As described above, in order to rotate the lead screw  16 , the lever  18  should first be inserted into the interlock device  17 , and thus problems may occur depending on an arrangement of the door  12 . 
     In other words, when the door  12  is hinge-fastened to one side of the switchgear  10 , if a hinge point is distorted over time due to misalignment or weight of the door  12 , the lever  18  may not be smoothly inserted into the interlock device  17 . Therefore, a free end of the conventional lever  18  is taper-machined to allow the lever to smoothly enter the inside of the interlock device  17 . In this case, however, since the lever  18  is generally made of a metal material and a housing of the interlock device  17  is formed of a plastic material, there is a problem that the interlock device  17  may be damaged. 
     SUMMARY OF THE INVENTION 
     The present disclosure has been made to solve the above problems, and the present disclosure is to providing a switchgear including an interlock device for a vacuum circuit breaker, which has improved durability and is less affected by a coupling state of a door. 
     In order to achieve the above object, the present disclosure provides a switchgear including: a housing having an opened front side and forming an external appearance; a door hinge-coupled to the front side of the housing to open or close the front side of the housing; a circuit breaker main body disposed inside the housing to be movable forward and rearward; a transfer part disposed between the housing and the circuit breaker main body to move the circuit breaker main body; and an interlock device configured to restrict the driving of the transfer part when the door is opened 
     The transfer part may include: a fixed frame fastened to the housing; a lead screw disposed on the fixed frame to receive a rotational force from a manipulating handle configured to enter the housing from the outside of the door and fastened to one end arranged at the front side; a carriage configured to support the circuit breaker main body and moved by the lead screw; and a push block fastened to the lead screw in an original state to restrict the rotation of the lead screw and moved rearward when the manipulating handle is fastened thereto to release the fastening with the lead screw. 
     The lead screw may be provided with a nut-shaped rotation preventing protrusion disposed on an outer circumferential surface thereof, and the push block may be provided with a rotation preventing groove having a shape corresponding to that of the rotation preventing protrusion. 
     The interlock device may restrict the rearward movement of the push block when the door is opened. 
     The interlock device may include: a body fixed to the fixed frame and provided with a front hole and a lower hole; a movement preventing body movably disposed inside the body, the movement preventing body being configured to protrude outward from the lower hole of the body to come into contact with a rear side surface of the push block in its original state, and to enter the lower hole of the body to be spaced from the rear side surface of the push block in a moved state; an elastic body having one end disposed on the body and the other end disposed on the movement preventing body to provide a returning force such that the movement preventing member is moved to its original state; a button disposed inside the body such that one end thereof is in contact with the movement preventing body and having the other end protruding to the outside of the front hole of the body when the movement preventing body is in its original position; and a pressing protrusion disposed on an inner side surface of the door corresponding to the button, to press the button when the door is closed. 
     One side surface of the movement preventing body may be rounded, and one end of the button which is in contact with the movement preventing body may have an inclined shape to be inserted between one side surface of the movement preventing body and a lower side surface of the body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a conventional switchgear; 
         FIG. 2  is a view illustrating a conventional interlock device; 
         FIG. 3  is a partial side sectional view of a switchgear according to an embodiment of the present disclosure in which an interlock device for a vacuum circuit breaker is disposed; 
         FIG. 4  is an enlarged view of the inside of the switchgear in  FIG. 3  when a door is closed; 
         FIG. 5  is a perspective view of the interlock device for a vacuum circuit breaker of the switchgear according to an embodiment of the present disclosure; and 
         FIG. 6  is a side sectional view of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. While the present disclosure is shown and described in connection with exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the disclosure. 
     Unless otherwise defined, all terms used herein have the same meaning as the general meaning of terms understood by one of ordinary skill in the art, and if the terms used herein conflict with a general meaning of terms used in the art, these terms will be employed according to a definition prescribed herein. 
     However, the disclosure to be described below is not intended to limit the scope of the present disclosure, but to describe embodiments of the present disclosure, and the same reference numerals throughout the specification represent the same components. 
       FIG. 3  is a partial side sectional view of a switchgear according to an embodiment of the present disclosure in which an interlock device for a vacuum circuit breaker is disposed,  FIG. 4  is an enlarged view of the inside of the switchgear in  FIG. 3  when a door is closed,  FIG. 5  is a perspective view of the interlock device for a vacuum circuit breaker of the switchgear according to an embodiment of the present disclosure, and  FIG. 6  is a side sectional view of  FIG. 5 . 
     Referring to  FIGS. 3 to 6 , a switchgear  100  according to an embodiment of the present disclosure may largely include a housing  110 , a door  120 , a circuit breaker main body  130 , a transfer part  140 , and an interlock device  150 . 
     The housing  110  has an opened front side to form an external appearance of the switchgear  100 , and may be formed in the shape of a substantially rectangular parallelepiped or regular hexahedron. 
     The circuit breaker main body  130 , the transfer part  140 , and the interlock device  150 , which are described later, may be accommodated in the above-described housing  110 , and other components constituting the switchgear  100  may be accommodated in the housing. 
     The door  120  may be hinge-connected to the front side of the housing  110  to open and close the front side of the housing  110 . 
     In addition, a pressing protrusion  155  that is described later may be fastened to an inner side surface of the door  120  to correspond to a location of a button  154  that is described later, and an entry hole  121  may be formed in a lower side surface of the door  120 . Here, a separate manipulating handle  1  for rotating a lead screw  142  that is described later may be inserted into the entry hole  121 . 
     The circuit breaker main body  130  may be disposed inside the housing  110  to be moved forward and rearward, and may be moved rearward to be electrically coupled to a terminal  111  which may be connected to an external terminal. 
     The transfer part  140  may constitute a circuit breaker together with the circuit breaker main body  130 , and may be disposed between the housing  110  and the circuit breaker main body  130  to move the circuit breaker main body  130  forward and rearward. 
     Here, the term “forward” means a direction directed towards the door  120 , and the term “rearward” may mean a direction directed towards a sidewall, at which the terminal  111  is disposed, which is opposite to the door  120 , in the housing  110 . The transfer part  140  is provided for moving the circuit breaker main body  130 , as described above, and may include a fixed frame  141 , the lead screw  142 , a carriage  143 , and a push block  144 . 
     The fixed frame  141  supports a lower side of the circuit breaker main body  130 , and may be fastened and fixed to the housing  110 . 
     The lead screw  142  may be disposed in the fixed frame  141  to receive a rotational force from the manipulating handle  1 , which enters the housing from the outside of the door  120  and is fastened to one end of the lead screw arranged at a front side of the housing. 
     The carriage  143  is disposed on the fixed frame  141  to support the circuit breaker main body  130 , and may be moved by the lead screw  142  to move the circuit breaker main body  130 . 
     The push block  144  is provided to prevent the inadvertent rotation of the lead screw  142 , and fastened to the lead screw  142  in an original state to limit the rotation of the lead screw  142 . When the manipulating handle  1  is fastened thereto, the push block  144  may be moved rearward to release the fastening with the lead screw  142  and the push block. 
     Specifically, a nut-shaped rotation preventing protrusion  142   a  is disposed on an outer circumferential surface of the lead screw  142 . In addition, the push block  144  may be formed with a rotation preventing groove  144   a  having a shape corresponding to that of the rotation preventing protrusion  142   a.    
     Under such a configuration, in a state that is not pressed by the manipulating handle  1 , the push block  144  is disposed at the front side to allow the rotation preventing groove  144   a  to come into contact with an outer side surface of the rotation preventing protrusion  142   a  or to be spaced from the rotation preventing protrusion by a certain distance, and thus it is possible to restrict the rotation of the lead screw  142 . 
     When the manipulating handle  1  enters the housing through the door  120  and is fastened to a front portion of the lead screw  142  and then pressed, the push block  144  is moved rearward by a pressing force of the manipulating handle  1 , and as a result, the lead screw  142  may be in a rotatable state. 
     However, the interlock device  150  according to the embodiment of the present disclosure restricts the rearward movement of the push block  144  when the door  120  is opened, and thus it is possible to further improve the stability of the switchgear  100  according to an embodiment of the present disclosure. 
     Specifically, the interlock device  150  may include a body  151 , a movement preventing body  152 , an elastic body  153 , the button  154 , and the pressing protrusion  155 . 
     The body  151  is fixed to the fixed frame  141  and may have a front hole  151   a  and a lower hole  151   b  formed therein. Such the body  151  may be directly fixed to the fixed frame  141  or fixed to the fixed frame via a separate bracket. 
     Referring to  FIGS. 4 to 6 , the movement preventing body  152  is movably disposed inside the body  151 . However, the movement preventing body  152  may be configured to protrude outward from the lower hole  151   b  of the body  151  to come into contact with a rear side surface of the push block  144  in its original state, and to enter the lower hole  151   b  of the body to be spaced from the rear side surface of the push block  144  in a moved state. 
     In other words, the movement preventing body  152  may be moved in one direction (an upward direction in the drawing) inside the body  151  when an external force is applied from a device such as a cylinder. 
     One end of the elastic body  153  is disposed on the body  151  and the other end is disposed on the movement preventing body  152  to provide a returning force to allow the movement preventing body  152  to be moved to its original state. A coil spring accommodating the movement preventing body  152  may be employed as the elastic body  153 . 
     The button  154  is disposed inside the body  151  so that one end thereof is in contact with the movement preventing body  152 , and the other end of the button may protrude to the outside of the front hole  151   a  of the body  151  when the movement preventing body  152  is in its original position. 
     Due to the above-described button  154 , the pressing protrusion  155  that is described later does not enter the body  151  so that durability of the interlock device  150  according to an embodiment of the present disclosure can be enhanced. 
     In addition, in consideration of the functions of the button  154  and the movement preventing body  152 , one side surface of the movement preventing body  152  is formed to be rounded, and one end of the button  154  which is in contact with the movement preventing body  152  may have an inclined shape to be inserted between one side surface of the movement preventing body  152  and a lower side surface of the body  151  when the door  120  is closed. 
     The pressing protrusion  155  may be disposed on an inner side surface of the door  120  corresponding to the button  154 , to press the button  154  when the door  120  is closed. 
     In addition, in order for the pressing protrusion  155  to effectively press the button  154 , a cutting surface of the pressing protrusion  155  may be formed to have an area smaller than or equal to that of a cutting surface of the button  154 . 
     In addition, in order for the pressing protrusion  155  to effectively press the button  154 , a free end of the pressing protrusion  155  may protrude or may be recessed in a curved shape, and a free end of the button  154  may be recessed or may protrude in a curved shape. 
     In short, in the switchgear  100  according to the present disclosure, the structure of the interlock device  150  is improved to ensure accurate operation of the interlock device  150  regardless of a fastening precision of the door  120  with respect to the switchgear  100 . In addition, there is an advantage in that since the pressing protrusion  155  disposed on the door  120  does not come in contact with the body  151  of the interlock device  150 , durability can be improved. 
     The present disclosure is improved to have the structure in which a pressing protrusion disposed on an inner side surface of a door presses a button protruding to the outside of an interlock device, rather than a structure in which the pressing protrusion does not enter the inside of the interlock device, so that durability of the interlock device is enhanced and it is possible for the interlock device to accurately prevent the rotation of a lead screw. 
     It will be apparent to those skilled in the art that various modifications and changes can be made to the above-described exemplary embodiments of the present disclosure without departing from the spirit or scope of the disclosure. In addition, the technical scope of the present disclosure should not be limited to the contents described in the embodiments, but should be defined by the appended claims and their equivalents.