Abstract:
An apparatus includes an enclosure comprising first and second abutting compartment and at least one cable passing between the first and second compartments through a sealing multi-cable transit mounted in a wall shared by the first and second compartments. The first compartment may contain arc-generating equipment and the second compartment may contain equipment vulnerable to arc damage. The first compartment may include a medium-voltage cubicle and the second compartment may include a low-voltage control cubicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 62/288,610, filed Jan. 29, 2016, the contents of which are hereby incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Medium voltage electrical equipment, such as adjustable frequency drives, typically includes circuitry that operates at relatively high voltages (e.g., multiple kV) that can pose a risk of high-energy arcs. Such arcs may generate gasses, flame, pressure and debris, which may damage vulnerable circuitry, such as control circuitry. While arc-generating and arc-vulnerable circuitry may be housed within respective compartments (e.g., cubicles) of an equipment enclosure, gasses, flame, pressure and debris produced by an arc in one compartment can enter adjacent compartments. 
         [0003]    It can be particularly challenging to seal between compartments particularly in areas where cables enter/exit/pass between the compartments. For an arc resistant enclosure to achieve a 2B rating, it must be able to withstand an arc without allowing gasses to enter the control cubicle. The control cubicle often contains many wires and cables that enter and exit the cubicle. If the cable passageway is not sealed, gasses could potentially breach the cubicle. Conventional methods of sealing, such as using silicone RTV, may be undesirable as a manufacturing process because it may be difficult to obtain a positive seal around cable bundles and because results may vary from one installer to another. In addition, movement of cables (particularly when placed across a hinge) can pull at the silicone and break the seal. 
       SUMMARY OF THE INVENTION 
       [0004]    According to some embodiments, an apparatus includes an enclosure comprising first and second abutting compartment and at least one cable passing between the first and second compartments through a sealing multi-cable transit mounted in a wall shared by the first and second compartments. The first compartment may contain arc-generating equipment and the second compartment may contain equipment vulnerable to arc damage. The first compartment may include a medium-voltage cubicle and the second compartment may include a low-voltage control cubicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIGS. 1A and 1B  illustrate a multiple compartment enclosure with intercompartment seals according to some embodiments, 
           [0006]      FIG. 2  illustrates an intercompartment seal according to some embodiments. 
           [0007]      FIG. 3  illustrates an intercompartment seal according to further embodiments. 
           [0008]      FIG. 4  illustrates a multiple compartment enclosure with intercompartment seals according to further embodiments 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    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. 
         [0010]    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. 
         [0011]    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. 
         [0012]    According to some embodiments of the inventive subject matter, a flexible Multi Cable Transit (MCT) can be used to provide sealed cable paths between compartments of an enclosure to reduce or prevent the spread of arc gasses and pressures between compartments. Commercially available MCTs typically combine a mounting frame with a module insert. The MCT may include a compression plate or ring that compresses the module insert around a cable to provide a seal. An MCT may be used to provide a cable seal between a control compartment and a compartment housing equipment capable of generating arcs. An MCT can also be applied between structures when integrating equipment already containing arc ratings with equipment that does not have an arc rating. The integration may require cable pass-through between equipment, and using an MCT to seal these pass-throughs may allow the certified equipment to retain its rating without the need to retest. 
         [0013]      FIGS. 1A and 1B  illustrate an enclosure  100  according to some embodiments. The enclosure  100  includes a first compartment  110  that is configured to house arc-generating equipment. A second compartment  120  is configured to house equipment that may be damaged by gasses, flame, and pressure produced by an arc in the first compartment  110 . First and second MCTs  130 ,  140  are provided in a wall shared by the compartments  110 ,  120  to seal cables passing between the first and second compartments  110 ,  120 . The first and second MCTs  130 ,  140  may be, for example, Roxtec RG M63 cable glands and Roxtec CF16 compact seals distributed by Roxtec International AB. Referring to  FIG. 2 , the MCT  130  may include user configurable compression modules  132  having removable concentric rings that may be selectively removed to provide a tailored fit around a cable. The compression modules  132  are configured to be compressed by a compression screw ring  134  to provide a seal where the cable passes through a compartment wall. Referring to  FIG. 3 , the MCT  140  may have rectangular shape and include similar compressible modules  142  that are compressed using a frame  144 . The MCTs  130 ,  140  utilize compressible seals to prevent passage of flame and gasses between the compartments  110 ,  120 . 
         [0014]      FIG. 4  illustrates an example application in medium voltage equipment. A device includes a medium-voltage compartment or cubicle  410  housing equipment that operates at voltages that may generate arcs. Low-voltage control cubicles  420   a,    420   b  have MCTs  430 ,  440  mounted in wall shared with the medium-voltage cubicle  410  to provide sealed entrance/exit points for cables passing between the medium-voltage cubicle  410  and the control cubicles  420   a ,  420   b.  The MCTs  430 ,  440  may reduce or prevent passage of flame, gas and debris into the control cubicles  420   a,    420   b.    
         [0015]    In this specification, there have been disclosed embodiments of the inventive subject matter and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. The following claims are provided to ensure that the present application meets all statutory requirements as a priority application in all jurisdictions and shall not be construed as limiting the scope of the inventive subject matter.