Abstract:
A withdrawable control compartment for mounting breaker control and measurement devices therein is provided. The compartment is withdrawable upon rollers and allows for quick disconnection of the devices from the energized parts of the switchgear. The compartment is secured in a cell of a switchgear enclosure using flanges in removeable engagement with brackets. The flanges are attached to the compartment and the brackets are attached to opposing sides of the frame of the switchgear enclosure.

Description:
FIELD OF INVENTION 
       [0001]    The present application is directed to a control compartment for electrical switchgear. 
       BACKGROUND 
       [0002]    Electrical switchgear installations, particularly for low voltage applications, often have breaker control and measurement devices mounted in a dedicated control compartment. In order to perform maintenance or replace the devices installed in the dedicated control compartment, the devices must be disconnected or otherwise segregated from the electrical power source. Known compartments for housing breaker control and measurement devices must be completely disassembled in order to disconnect the compartments from the power source and commence maintenance on the devices. Thus, there is a need for improvement in control compartment design of electrical switchgear. 
       SUMMARY 
       [0003]    An object of the present invention is to provide electrical switchgear having at least one withdrawable compartment that is removeable from the switchgear cell in which the at least one withdrawable compartment is housed. The at least one withdrawable compartment is removeable from the cell on rollers that are mounted in and protrude from a base of the cell. The rollers contact a bottom surface of the withdrawable compartment when the withdrawable compartment is removed from or inserted into the cell. 
         [0004]    A withdrawable compartment for mounting electrical devices therein, has a top wall, bottom wall, side walls, and a rear wall. The withdrawable compartment is adapted for removeably mounting in a cell of an electrical switchgear unit and is removeable on rollers protruding from a surface of the bottom wall. The rollers contact a bottom surface of the withdrawable compartment when the withdrawable compartment is removed from or inserted into the corresponding cell of the switchgear unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    In the accompanying drawings, structural embodiments are illustrated that, together with the detailed description provided below, describe exemplary embodiments of a withdrawable control compartment for switchgear. One of ordinary skill in the art will appreciate that a component may be designed as multiple components or that multiple components may be designed as a single component. 
           [0006]    Further, in the accompanying drawings and description that follow, like parts are indicated throughout the drawings and written description with the same reference numerals, respectively. The figures are not drawn to scale and the proportions of certain parts have been exaggerated for convenience of illustration. 
           [0007]      FIG. 1  is a perspective view of a switchgear enclosure having at least one withdrawable compartment and a front door removed from the least one withdrawable compartment; 
           [0008]      FIG. 2   a  shows the at least one withdrawable compartment having the front door and a handle mounted thereon; 
           [0009]      FIG. 2   b  shows the at least one withdrawable compartment having the front door and a latch mounted therein; 
           [0010]      FIG. 3  shows the at least one withdrawable compartment having the front door removed; 
           [0011]      FIG. 4  is a side view of the at least one withdrawable compartment showing an inset of a knock-out panel; 
           [0012]      FIG. 5  is perspective view of a cell of the switchgear enclosure, further depicting rollers in an inset; and 
           [0013]      FIG. 6  is a side view of the at least one withdrawable compartment secured in a cell of the switchgear enclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    With reference to  FIG. 1 , a low-voltage electrical switchgear  100  is depicted. The switchgear  100  is housed by an enclosure  70  having at least one withdrawable compartment  10 , a device section  22 , a bus bar section  24 , and a cable section  26 . The enclosure  70  is formed from reinforced sheet metal. The device, bus bar, and cable sections  22 ,  24 ,  26  are separated by walls  27  that are formed of connected panels of sheet metal. 
         [0015]    Low voltage, as used herein, generally refers to voltages that do not exceed 600 volts. Although the low voltage electrical switchgear (hereinafter “switchgear”) is depicted, it should be understood that the enclosure  70  and the at least one withdrawable compartment  10  may be adapted for use in medium voltage switchgear applications that range from about 600 volts to about 38 kV. 
         [0016]    With continued reference to  FIG. 1 , the enclosure  70  has cells  14  for housing withdrawable devices such as circuit breakers, instruments, meters, and control devices. The enclosure  70  depicted has four cells  14  vertically arranged, three of which have the at least one withdrawable compartment  10  mounted therein and the uppermost cell has the withdrawable compartment  10  removed. It should be understood that the switchgear configuration, including the number of cells  14 , may differ depending on the application. 
         [0017]    Referring now to  FIG. 3 , the at least one withdrawable compartment  10  has top, side, rear and bottom walls  34 ,  29 ,  39 ,  36 ,  40 . The at least one withdrawable compartment  10  is removeable from the enclosure  70  to provide quick disconnection and isolation from electrical power to the devices mounted inside the at least one withdrawable compartment  10 . 
         [0018]    The devices are typically mounted to the rear and bottom walls  36 ,  40  of the at least one withdrawable compartment  10 . The at least one withdrawable compartment  10  houses devices such as the following: meters, terminal blocks, relays, breaker control switches, push buttons, pilot lights, mini-breakers, fuses and other instrumentation used in breaker control. 
         [0019]    Referring now to  FIGS. 2   a  and  2   b , a front door  42  is provided to secure the devices in the at least one withdrawable compartment  10  and further secure the at least one withdrawable compartment  10  in the corresponding cell  14 . The front door  42  is secured by a handle  44  or a latch  46 , such as a quarter-turn latch. In one embodiment, the handle  44  is a t-handle and the rotation of the handle  44  causes attached rods to engage with or release from a recess in a wall of the corresponding cell  14 . The embodiment having the exemplary t-handle and attached rods renders the at least one withdrawable compartment  10  resistant to arc flashes. 
         [0020]    The at least one withdrawable compartment  10  has flanges  12 ,  37  mounted proximate to a front edge  48  of each of the side walls  29 ,  39 . The flanges  12 ,  37  extend outward from the side walls  29 ,  39 , respectively. The flanges  12 ,  37  are removeably secured to brackets  16 ,  19 , further securing the compartment  10  in place in the corresponding cell  14 . One of the flanges  37  is a flat metal bar having a uniform edge and the other flange  12  has an extension piece extending from the center of a flat metal bar. 
         [0021]    Each of the brackets  16 ,  19  are attached to the periphery of the frame  70  of the switchgear  100  and extend between a top and bottom surface of the corresponding cell  14 . The brackets  16 ,  19  releasably engage with the flanges  12 ,  37 . The brackets  16 ,  19  are releasably engaged to the flanges  12 ,  37  by bolting the brackets  16 ,  19  to the corresponding one of the flanges  12 ,  37  as shown in  FIG. 6  or disengaged by removing the bolt that secures the bracket  16 ,  19  to the corresponding flange  12 ,  37 . 
         [0022]    Referring now to  FIG. 4 , the withdrawable compartment  10  has a knock-out panel  30  formed in a side wall  29 ,  39 . The knock-out panel  30  is die-cut to form perforations  31  in the sheet metal that hold each of the sides of the knock-out panel  30  in place along the side wall  29 ,  39 . Although the knock-out panel  30  is depicted as rectangular in  FIG. 4 , it should be understood that any shape suitable for the application may be used. 
         [0023]    The knock-out panel  30 , when removed by severing the attached edges of the perforations  31 , allows cables and other connections made between the control compartment devices and power supply to be fed through the resulting generally rectangular opening  33 . 
         [0024]    Referring now to  FIG. 5 , the withdrawable compartment  10  is removeable from or insertable into the corresponding cell  14  of the enclosure  70  along rollers  50  that are mounted in a base of the cell  14 . The rollers  50  contact the bottom surface of the compartment, to translate rotational movement of the rollers  50  to linear movement of the compartment  10  along the base  60  of the corresponding cell  14 , so that the compartment  10  can be removed from the corresponding cell  14 . The wheels of the rollers  50  do not engage with a track, but rather move along the contact surface, the bottom wall  40 , of the at least one withdrawable compartment  10  as the at least one withdrawable compartment  10  is being withdrawn from the cell  14 . 
         [0025]    The rollers  50  have a housing  54  inside which are mounted wheels  52  upon an axle (not shown). The wheels  52  extend slightly above a top surface of the housing  54 . There is about 2.5 mm of clearance between the bottom wall  40  of the compartment  10  and the base  60  of the corresponding cell  14 . Although nine rollers  50  are depicted in the base  60  of the exemplary cell  14  shown in  FIG. 5 , it should be understood that any number of rollers  50  suitable for the application may be utilized. 
         [0026]    The rollers  50  work in concert with the knock-out panel  30  to facilitate quick electrical disconnection, such as between the control compartment devices and power supply, through the removed knock-out panel  30  and the removal of the compartment  10  from the corresponding cell  14  along the rollers  50 . 
         [0027]    Grates  52  are disposed proximate to the edges of the bottom surface of the compartment  10 . When the compartment  10  is secured in the cell  14  as depicted in  FIG. 6 , the grates  52  surrounding the compartment  10  are unobstructed. The grates  52  provide ventilation to devices mounted in the device section  22 . 
         [0028]    While the present application illustrates various embodiments, and while these embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative embodiments, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.