Abstract:
A grounding and test device includes a chassis configured to be removably installed in a drawout switchgear compartment (e.g., a breaker compartment) having a load conductor and a line conductor therein. The device also includes an interconnection bus supported by the chassis and a ground conductor supported by the chassis. The device further includes a first vacuum circuit interrupter supported by the chassis and configured to selectively couple and decouple the interconnection bus and the line conductor, a second vacuum circuit interrupter supported by the chassis and configured to selectively couple and decouple the interconnection bus and the load conductor and a third vacuum circuit interrupter supported by the chassis and configured to selectively couple and decouple the interconnection bus and the ground conductor.

Description:
BACKGROUND 
       [0001]    The inventive subject matter relates to power distribution apparatus and methods of operating the same and, more particularly, to power distribution test apparatus and methods. 
         [0002]    Ground and test devices are commonly used to create an electrically safe environment when working on enclosed medium voltage electrical switchgear. These devices typically have a chassis designed to be installed in a draw-out switchgear compartment and include contacts configured to engage phase and/or load conductor buses in the switchgear compartment when the device is installed. The ground and test device may be configured to ground the line and/or load conductors, and may include test ports or other features to facilitate testing. 
         [0003]    A standard for ground and test devices is IEEE C37.20.6 “IEEE Standard for 4.76 kV to 38 kV Rated Ground and Test Devices Used in Enclosures.” The standard identifies four types of ground and test devices: (1) simple manual; (2) complex manual; (3) simple electrical; and (4) complex electrical. A simple manual device has upper and/or lower terminals with provision for connecting phase conductors to ground. A complex device has upper and/or lower terminals and has a manually operated switch configured to connect the upper or lower terminals to a set of test terminals which, in turn, may be connected to ground. A simple electrical device has a set of upper terminals or a set of lower terminals and an electrically operated switch that is configured to connect the upper or lower terminals to ground even if the system is energized. A complex electrical system has a manually operated switch that is configured to connect upper and/or lower terminals to a power-operated grounding switch, and may be used to apply a ground even if the system is energized. 
       SUMMARY 
       [0004]    Some embodiments of the inventive subject matter provide a grounding and test device including a chassis configured to be removably installed in a drawout switchgear compartment (e.g., a breaker compartment) having a load conductor and a line conductor therein. The device also includes an interconnection bus supported by the chassis and a ground conductor supported by the chassis. The device further includes a first vacuum circuit interrupter supported by the chassis and configured to selectively couple and decouple the interconnection bus and the line conductor, a second vacuum circuit interrupter supported by the chassis and configured to selectively couple and decouple the interconnection bus and the load conductor and a third vacuum circuit interrupter supported by the chassis and configured to selectively couple and decouple the interconnection bus and the ground conductor. 
         [0005]    The first vacuum circuit interrupter may include a plurality of first vacuum circuit interrupters, respective ones of which are configured to selectively couple and decouple the interconnection bus and respective ones of a plurality of line conductors. The second vacuum circuit interrupter may include a plurality of second vacuum circuit interrupters, respective ones of which are configured to selectively couple and decouple the interconnection bus and respective ones of a plurality of load conductors. 
         [0006]    In some embodiments, the chassis includes a housing having a vertical rear face configured to face into the switchgear compartment when the chassis is installed. The first vacuum circuit interrupter may be included in a first elongate pole unit mounted on and extending from the vertical rear face of the housing, and the second vacuum circuit interrupter may be included in a second elongate pole unit mounted on and extending from the vertical rear face of the housing. A first end of the first pole unit may be mounted at the vertical rear face of the housing and the first pole unit may include a contact disposed at a second end of the first pole unit and configured to engage the line conductor when the chassis is installed in the breaker compartment. A first end of the second pole unit may be mounted at the vertical rear face of the housing and the second pole unit may include a contact disposed at a second end of the second pole unit and configured to engage the load conductor when the chassis is installed in the breaker compartment. 
         [0007]    The interconnection bus may include an elongate bus bar extending horizontally between the first and second pole units and mounted on the vertical rear face of the housing. The device may include at least one insulating standoff mounted on the vertical rear face of the housing and supporting the bus bar. 
         [0008]    The third vacuum circuit interrupter may be included in a third elongate pole unit mounted on the chassis beneath the first and second pole units and the bus bar and extending longitudinally in a direction orthogonal to longitudinal axes of the first and second pole units. The bus bar may include a first bus bar and the device may further include a second elongate bus bar connected to the first bus bar and extending perpendicularly therefrom to contact a terminal of the third pole unit. 
         [0009]    The device may further include a controller supported by the chassis and configured to control the first and second pole units. The device may also include a first control switch coupled to the controller and configured to control the first vacuum circuit interrupter pole unit and a second control switch coupled to the controller and configured to control the second vacuum circuit interrupter pole unit. The controller and the first and second switches may be mounted in a panel removably attached at the front face of the housing. 
         [0010]    According to further embodiments of the inventive subject matter, a grounding and test device includes a chassis configured to be removably installed in a drawout switchgear compartment having a plurality of load conductors and a plurality of line conductors therein. The chassis includes a housing having a vertical front face configured to face outward from the circuit breaker housing when the chassis is installed therein and a vertical rear face on an opposite side of the housing from the first vertical face and configured to face inside the switchgear compartment. The device also includes a horizontal row of spaced apart first vacuum circuit interrupter pole units mounted on the vertical rear face of the housing and extending perpendicularly therefrom. The first vacuum circuit interrupter pole units have respective contacts configured to engage respective ones of the plurality of line conductors. A horizontal row of spaced apart second vacuum circuit interrupter pole units is mounted on the vertical rear face of the housing and extend perpendicularly therefrom parallel to the row of first vacuum circuit interrupter pole units. The second vacuum circuit interrupter pole units have respective contacts configured to engage respective ones of the plurality of load conductors. The device further includes an elongate interconnection bus bar mounted on the vertical rear face of the housing and extending horizontally between the rows of first and second vacuum circuit interrupter pole units. Respective flexible conductors extend perpendicularly from the interconnection bus bar and connect respective ones of the first and second vacuum circuit interrupter pole units to the interconnection bus bar. A ground conductor is supported by the chassis and a third vacuum circuit interrupter pole unit is supported by the chassis and coupled between the interconnection bus bar and the ground conductor. 
         [0011]    Further embodiments provide methods including installing a grounding and test device in a drawout switchgear compartment having a load conductor and a line conductor therein. The grounding and test device includes a first vacuum circuit interrupter configured to coupled between an interconnection bus and the line conductor, a second vacuum circuit interrupter configured to be coupled between the interconnection bus and the load conductor, and a third vacuum circuit interrupter configured to be coupled between the interconnection bus and a ground conductor. The methods include closing the first third vacuum circuit interrupter and the third vacuum circuit interrupter while maintaining the second vacuum circuit interrupter in an open state to ground the line conductor and closing the second vacuum circuit interrupter and the third vacuum circuit interrupter while maintaining the first vacuum circuit interrupter in an open state to ground the load conductor. The methods further include closing the first and second vacuum circuit interrupters while maintaining the third vacuum circuit interrupter in an open state. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a front elevation of a grounding and test device according to some embodiments. 
           [0013]      FIG. 2  is a side elevation of the grounding and test device of  FIG. 1 . 
           [0014]      FIG. 3  is a detailed side view of a vacuum circuit interrupter pole unit of the grounding and test device of  FIGS. 1 and 2 . 
           [0015]      FIG. 4  is front elevation of the grounding and test device of  FIGS. 1 and 2  with a front cover removed. 
           [0016]      FIGS. 5 and 6  are side and rear elevations of the front cover of the grounding and test device of  FIGS. 1 and 2 . 
           [0017]      FIGS. 7-11  are schematic diagrams illustrating operations of the grounding and test device of  FIGS. 1 and 2  according to further embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Specific exemplary embodiments of the inventive subject matter now will be described with reference to the accompanying drawings. This inventive subject matter may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive subject matter to those skilled in the art. In the drawings, like numbers refer to like elements. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0019]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive subject matter. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0020]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0021]      FIGS. 1-4  illustrate a complex electrically-operated test and grounding device  100  according to some embodiments of the inventive subject matter. The test and grounding device  100  includes a chassis  110 , which is configured to be removably installed in a draw-out switchgear compartment, such as a compartment configured to receive a medium-voltage circuit breaker. The chassis  110  may include features, such as rollers  130 , configured to facilitate insertion and removal of the chassis from the switchgear compartment. The chassis  110  further includes a control housing  170  having a vertically-oriented front face  172  and a vertically-oriented rear face  174 . A front panel  120  is mounted at the front face  172 , and includes control circuitry described in detail below. 
         [0022]    Vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c  are mounted on the rear face  174  of the control housing  170 . The vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c  extend longitudinally from the rear face  174  of the control housing  1790  and are arranged such that primary disconnects (stabs)  330  thereof are configured to engage upper and lower buses  10 ,  20  within the switchgear compartment when the grounding and test device  100  is installed. It will be appreciated that the upper and lower buses  10 ,  20  may be line and load buses, respectively, but it will be further appreciated that other arrangements of vacuum circuit interrupter devices may be used. The contact arrangement illustrated is also provided for purposes of illustration, and other stab arrangements, such as stabs configured to engage vertical conductors or rounded conductors may be used. 
         [0023]    Referring to  FIGS. 2 and 4 , the vacuum circuit interrupter pole units  142   a ,  144   a,    142   b,    144   b,    142   c,    144   c  are arranged in upper and lower horizontal rows. An interconnection bus bar  152  extends horizontally between the rows of vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c  and is coupled thereto by respective flexible conductors  154   a,    156   a,    154   b,    156   b,    154   c,    156   c.  At intersections of the flexible conductors  154   a,    156   a,    154   b,    156   b,    154   c,    156   c  with the interconnection bus bar  152  are insulating standoffs  160  that are mounted at the rear face  174  of the control housing  170  and support the interconnection bus bar  152 . As shown in  FIG. 4 , test ports  197  may be provided for probing line and load conductors associated with respective ones of the vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c.  The test ports  197  may be concealed when the front panel  120  is in place. 
         [0024]    Another vacuum circuit interrupter pole unit  180 , which is used as a grounding switch, is positioned below the rows of vacuum circuit interrupter pole units  142   a,    144   a ,  142   b,    144   b,    142   c,    144   c,  and extends longitudinally in a direction orthogonal to the longitudinal axes of the vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c ,  144   c.  One terminal of the grounding vacuum circuit interrupter pole unit  180  is coupled to the interconnection bus bar  152  by a vertically extending bus bar  158 . Another terminal of the grounding vacuum circuit interrupter pole unit  180  is coupled to a ground contact  190 . Although the figures illustrate connection of the vacuum circuit interrupter pole unit  180  to a ground contact  190  located near the base of the chassis  110 , it will be appreciated that other arrangements may be used. 
         [0025]      FIG. 3  is a detailed view of a vacuum circuit interrupter pole unit  142   a.  The pole unit  142   a  includes a vacuum circuit interrupter  310 . The vacuum circuit interrupter  310  is actuated by an electromagnetic actuator  320  at a first end  312  of the pole unit  142   c  via a drive rod  340 . A first terminal of the vacuum circuit interrupter  310  is electrically coupled to a primary disconnect or stab  330  disposed at a second end  314  of the pole unit  142   c.  A second terminal of the vacuum circuit interrupter  310  is electrically coupled to a flexible connector  154   c  that is coupled to the interconnection bus  152  at an insulating standoff  160 . 
         [0026]    Referring to  FIGS. 5 and 6  with continuing reference to  FIGS. 1 and 2 , the front panel  120  of the grounding and test device  100  is supports a controller circuit assembly  120  and power supply assemblies  129  that provide power thereto. Switch units  122   a,    122   b,    122   c ,  124   a,    124   b,    124   c,    126  including pairs of pushbutton switches  113 ,  114  and a switch position indicator  115  are disposed at a front face of the front panel  120 . The controller circuit assembly  128  is configured to control the vacuum circuit interrupter pole units  142   a,    144   a ,  142   b,    144   b,    142   c,    144   c,    180  responsive to user inputs provided via the switch units  122   a ,  122   b,    122   c,    124   a,    124   b,    124   c,    126 . In particular, the controller circuit assembly  128  electrically drives the magnetic actuators of respective ones of the vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c,    180  to open and close vacuum circuit interrupter contacts thereof responsive to user inputs provided using respective ones of the switch units  122   a,    122   b,    122   c,    124   a,    124   b,    124   c,    126 . The controller circuit assembly  128  drives the magnetic actuators of the vacuum circuit interrupter pole units  142   a,    144   a,    142   b ,  144   b,    142   c,    144   c,    180  using energy stored in capacitors  195  disposed below the vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c.    
         [0027]      FIGS. 7-11  illustrate various test and grounding configurations that may be provided by the grounding and test apparatus  100 . As shown in  FIGS. 7-9 , individual phase and load conductors may be connected while other phases and ground are disconnected to facilitate testing of individual phases. Referring to  FIGS. 10 and 11 , the vacuum circuit interrupter pole units  142   a,    144   a,    142   b,    144   b,    142   c,    144   c  may be selectively opened and closed to facilitate grounding of line and load conductors via the grounding vacuum circuit interrupter pole unit  180 . 
         [0028]    In the drawings and specification, there have been disclosed exemplary embodiments of the inventive subject matter. Although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the inventive subject matter being defined by the following claims.