Patent Publication Number: US-7719823-B2

Title: Modular insulation system

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
   This application is a Divisional of U.S. application Ser. No. 11/007,665, filed Dec. 8, 2004, incorporated herein by reference in its entirety. 

   FIELD 
   The present disclosure relates generally to the field of electrical switchboards and panel boards and more particularly to a modular insulation system for bus bars in switchboard and panel board enclosures. 
   BACKGROUND 
   Switchgear assemblies and switchboards and panel boards are general terms which cover metal enclosures, housing switching and interrupting devices such as fuses and circuit breakers, along with associated control, instrumentation and metering devices. Such assemblies typically include associated bus bars, interconnections and supporting structures used for the distribution of electrical power. Low voltage switchgear and switchboards operate at voltages of up to 600 volts and with continuous currents up to 5000 amps or higher. Such devices are also designed to withstand short circuit currents ranging up to 200,000 amps (3 phase RMS symmetrical). 
   Typical switchgear equipment is composed of a lineup of several metal and closed sections. Each section may have several circuit breakers stacked one above the other vertically in the front of the section with each breaker being enclosed in its own metal compartment. Each section has a vertical or section bus which supplies current to the breakers within the section by short horizontal branch busses, also referred to as run-in busses. The vertical bus bars in each section are supplied with current by a horizontal main bus bar that runs through the lineup of metal enclosed sections. The vertical bus bars may be configured as separate individual sections that require isolation from each other vertically as well as horizontally. A typical arrangement includes bus bars for each electrical phase of a multi-phase system which may include three power phases and a neutral. 
   In multi-phase systems, it is desirable to isolate the bus bars of each phase from each other and the other components in the enclosure. Isolation is beneficial to minimize hazards to personnel and to reduce arc fault hazards. Since configuration of switchboard enclosures and equipment vary from application and installation, a modular standard insulation system is easier to configure and install. 
   Thus there is a need for a modular insulation system for an electrical equipment enclosure having multi-phase vertical and horizontal bus bars. There is a further need to have an isolation system that can be easily configured, maintained, and installed without special tools and with a minimum of tools. 
   SUMMARY 
   There is provided a method for isolating phases in an electrical equipment enclosure having vertical bus bars and a mounting base for mounting electrical equipment. The method includes the steps of providing a plurality of side isolation barriers. A side barrier adapter is provided. Coupling the side barrier adapter to the mounting base and at least one side isolation barrier. An inner isolation barrier is provided. Coupling the inner isolation barrier to the mounting base to isolate at least two of the vertical bus bars from each other. A vertical bus rear wall is provided. A plurality of corner connectors are provided. Coupling the vertical bus rearwall and at least one side isolation barrier to at least one corner connector, wherein the vertical bus bars are individually isolated from each other. Another embodiment of the method of isolating phases includes the step of configuring the vertical bus rearwall with an opening for each runback bus bar. The methods may also include the step of providing an insulation shroud and coupling the insulation shroud to each runback bus bar. 
   There is further provided a modular insulation system kit for isolating phases in an electrical equipment enclosure with a modular insulation system. The enclosure includes a plurality of vertical bus bars and a mounting base for mounting electrical equipment. The kit includes a side barrier adaptor configured to couple to the mounting base and at least one side isolation barrier. An inner isolation barrier is configured to couple to the mounting base to isolate at least two of the vertical bus bars from each other. A vertical bus rear wall and at least one side isolation barrier are each configured to couple to at least one corner connector, wherein the vertical bus bars are individually isolated from each other. 
   There is further provided an electric equipment enclosure which includes a plurality of vertical bus bars coupled to the enclosure, with at least one vertical bus bar configured for each of an electrical phase. A horizontal bus bar is coupled to the at least one vertical bus bar for each electrical phase. A mounting base is coupled to the enclosure and configured to receive electrical equipment. A modular insulation system is configured to isolate the vertical bus bars of each electrical phase, The modular insulation system comprises a side barrier adapter coupled to the mounting base and at least one side isolation barrier. An inner isolation barrier is coupled to the mounting base and configured to isolate at least two vertical bus bars from each other. A vertical bus rear wall is coupled to at least one side isolation barrier with at last one corner connector, wherein the vertical bus bars are individually isolated from each other. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an electrical equipment enclosure including compartments for electrical equipment, such as circuit breakers and including an exemplary embodiment of a modular insulation system. 
       FIG. 2  is a perspective view of an electrical equipment enclosure from the rear aspect, including an exemplary embodiment of a multiple phase, vertical bus bars, with each vertical bus bar having three sections separated by a split bus barrier. 
       FIG. 3  is an exemplary embodiment of a mounting base for electrical equipment including a side barrier adapter and side isolation barrier of a modular insulation system on each of the two ends of the mounting base. 
       FIG. 4  is an exemplary embodiment of a mounting base for electrical equipment and including two inner isolation barriers of a modular insulation system configured to isolate bus bars in adjacent electrical phases. 
       FIG. 5  illustrates two views of an exemplary embodiment of a side barrier adapter for a modular insulation system. 
       FIG. 6  is a plan view of an exemplary embodiment of a side isolation barrier of a modular insulation system. 
       FIG. 7  is a perspective view of an exemplary embodiment of a corner connector of a modular insulation system. 
       FIG. 8  illustrates several views of an exemplary embodiment of an inner isolation barrier of a modular insulation system. 
       FIG. 9  is a perspective view of an exemplary embodiment of a split bus barrier of a modular insulation system defining two slots configured to interlock with the inner isolation barrier of the modular insulation system. 
       FIG. 10   a  is a perspective view of an exemplary embodiment of a mounting base with multiple phase runback bus bars extending through orifices defined in the mounting base with the runback bus bars partially encased in an insulation shroud of a modular insulation system. 
       FIG. 10   b  is a perspective view of one of the insulation shrouds illustrated in  FIG. 10   a.    
       FIG. 11  is a perspective view of an exemplary embodiment of an electrical equipment enclosure including a modular insulation system isolating the vertical bus bars from each other and illustrating several exemplary embodiments of a vertical bus rearwall having differently configured openings for bus bars, bus braces and ventilation arrangements 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   Before describing the exemplary embodiments of a modular insulation system for electrical equipment in an electrical equipment enclosure, for example, an electrical equipment enclosure, several comments are appropriate. Switchgear assemblies and panel board assemblies typically include vertical (section) bus bars to distribute electrical power within the enclosures. In a short circuit condition, extreme magnetic forces are created in the bus bars as a result of short circuit currents up to and including 200,000 amps symmetrical RMS flowing through each bus bar. In a three phase power system (typically) as a short circuit current flows through such bus bars, magnetic forces between adjacent bus bars tend to move such bus bars laterally (perpendicular) to the current flow. Such movement of the bus bars is typically prohibited or inhibited to avoid damage in arcing within an electrical equipment enclosures by bus bar brace apparatus and equipment arrangements within an electrical equipment cabinet. However, it is still expedient to provide isolation of the bus bars in each phase to further minimize arc flash and potential short circuit conditions. The modular insulation system that will isolate the bus bars from each other (and allow the enclosure designer or the maintenance of the enclosure) easier to configure and also easier to manufacture since standard components can be prepared and used for a variety of installation configurations. A modular insulation system kit including the several components described herein may also be provided in the field. 
   An additional advantage to use of the modular insulation system to isolate the bus bars within the several phases of the electrical equipment enclosure is the isolated phase vertical bus bars exhibit improved convection cooling which increases their continuous current capability. The bus bars can still be braced for short circuit conditions with the bus base brace apparatus without blocking air flow around or between the bus bar members. This “chimney effect” is also facilitated if the bus bars have a C-channel shape. Also, if two C-channel shape bus bars are aligned with their short sidewalls of each C-shaped bus bar facing each other, a spaced apart rectangular tube is formed which further facilitates air movement and thus cooling of the bus bar system. An example of such C-channel shaped bus bar is disclosed in U.S. patent application entitled ELECTRIC BUS BAR filed Dec. 8, 2004 (Ser. No. 11/007,664, now abandoned) and assigned to the assignee of the present application. 
   Referring now to the figures,  FIG. 1  is an illustration of exemplary embodiment of an electrical equipment enclosure  10 , without several of the outer panels for clarity purposes.  FIG. 1  also illustrates electrical equipment compartments for circuit breakers in the illustrated drawing mounted in the front of an electrical equipment cabinet  10 . A mounting base,  22  (not shown in  FIG. 1 ) forms the rear wall of the equipment compartment CB and is coupled to several of the frame members  12  of an electrical equipment enclosure  10 . 
     FIG. 1  specifically depicts a multi-phase switchgear assembly conventionally having three power phases, A B and C. A neutral bus or grounding bus can also be provided. In the illustration of  FIG. 1 , horizontal bus bars  18  feed the main electrical power to the enclosure  10  and to adjacent enclosures (not shown) in a typical installation. 
     FIG. 2  illustrates vertical bus bars  14  extended typically throughout the height of an electrical equipment enclosure  10  with horizontal bus bars  18  selectively positioned and connected mechanically and electrically to the vertical bus bars  14  for the distribution of power within the system. Spaced apart frame members  12  are mounted within an electrical equipment enclosure  10  at predetermined positions to support electrical equipment such as circuit breakers mounted in the enclosure  10 . The equipment can be accessed from either the front side  13  or the back side  11  of the enclosure  10 . An example of a typical electrical equipment that is mounted in an electrical equipment enclosure  10  is a circuit breaker CB. A circuit breaker mechanism is typically contained within a housing. The housing is coupled to a mounting base  22  which supports the circuit breaker housing and provides an apparatus for coupling the circuit breaker to the various bus bars within an electrical equipment enclosure  10 . A mounting plate system is used to attach the base member  22  to the frame members  12  of an electrical equipment enclosure  10 . 
     FIGS. 3-11  illustrate an exemplary embodiment of a modular insulation system for electrical equipment in an electrical equipment enclosure  10 . 
   Side isolation barriers  32  are configured in a planar arrangement having at least one edge  34  and another edge  36  used for attaching the side isolation barrier  32  to other components of the insulation system  30 . At least one slot  38  proximate one edge  34  of the barrier is defined in the side isolation barrier  32  and having at least one tab  40  defined along another edge  36  of the barrier  32 . 
   The side isolation barrier  32  is coupled to the mounting base  22  with a side barrier adapter  42 . (See  FIGS. 3 ,  5  and  6 .) The side barrier adapter  42  is configured with at least one snap lug  44  and also defines adapter slots  43  in each of the walls forming the side barrier adapter  42 . The snap lugs  44  engage slots defined in the mounting base  22  and the tabs  40  formed on the side isolation barriers  32  engage the adapter slots  43  in the side barrier adapter  42 . A typical arrangement is to have a side barrier adapter  42  and side isolation barrier  32  coupled to two sides (typically the narrower side) of the mounting base  22 . As illustrated in  FIGS. 1 and 2 , several side mounting barriers  32  are arranged vertically to isolate the vertical bus bars  14  in the enclosure. The side isolation barrier  32  can be fabricated from a flat sheet of insulating material and cut to size as is necessary to fit within an electrical enclosure  10 . 
     FIGS. 4 and 8  illustrate inner isolation barriers  46  configured to isolate at least two of the vertical bus bars  14  and coupled to the mounting base  22 . The inner isolation barrier  46  is secured to the mounting base  22  by a fastener such as a screw or a bolt or a rivet. In  FIG. 4 , two inner isolation barriers  46  are shown with the mounting base  22 .  FIG. 8  illustrates several views of an inner isolation barrier  46  to show different configurations, for example, one inner isolation barrier  46  is not configured with slots whereas another inner isolation barrier  46  includes a slot to facilitate the mounting of a split bus barrier  70 .  FIG. 2  illustrates a plurality of inner isolation barriers  46  mounted between the phases of the multiple phase vertical bus bars  14  in an electrical equipment enclosure  10 . 
   To complete the enclosure of the vertical bus bars  14 , in the enclosure  10 , the vertical bus rearwall  50  is configured to extend across the width of the enclosure and couple to the side isolation barriers  32  as illustrated in  FIG. 11 . A plurality of corner connectors  60  are provided to couple the vertical bus rearwall  50  with the side isolation barriers  32 . The corner connectors are configured with two walls  62 ,  64  and that are aligned at a 90° angle with each wall and configured to engage one of the cover slots  56  and the side isolation barrier slots  38 . (See  FIG. 7  which is a perspective view of a corner slot  60 .) The vertical bus rearwall  50  defines a plurality of slots  56  approximate at least two edges  52 ,  54  of the cover  50 . The vertical bus rearwall  50  is also fastened to the inner isolation barrier  46  with fasteners such as screws or the like. 
   The vertical bus rearwall  50  can be configured with a variety of openings  58  to accommodate various bus bar, bus brace and ventilation arrangements.  FIG. 11  illustrates three exemplary embodiments of a vertical bus rearwall  50  having various ventilating openings and bus bar openings. Connecting bus bars (not shown) extend through such openings  58  in the vertical bus rearwall  50  and couple the vertical bus bars  14  (See  FIG. 2 ) to selective horizontal bus bars  18  (See  FIG. 1 ). 
   The runback bus bars  19  typically extend through the mounting base  22  and couple the circuit breaker disconnects (not shown) to, for example, the cable terminals (not shown).  FIG. 10   a  illustrates a typical arrangement of three runback bus bars  19  (one for each phase) extending through a mounting base  22 . The runback bus bars  19  include an insulation shroud  68  which is a component of the modular insulation system  30 .  FIG. 10   b  illustrates an exemplary embodiment of an isolation shroud  68  for use with a runback bus bar  19 . 
   In some installations, the vertical bus bars  14  are separated vertically. The separate sections of the vertical bus bars  14  also require isolation between the vertical sections of the vertical bus bar  14 . (Such vertical bus sections are referred to as a split bus bar.)  FIG. 9  illustrates an exemplary embodiment of a split bus barrier  70  which isolates at least two sections of the vertical bus bar  14 .  FIG. 2  includes two split bus barriers  70  mounted between sections of the vertical bus bar  14  in each phase of the electrical distribution system within the enclosure  10 . 
   The side isolation barrier  32 , side barrier adapter  42 , inner isolation barrier  46 , vertical bus rearwall and the corner connectors  60  can be composed of a thermoplastic material. In some installations, the components can be composed of a thermal plastic that is a clear polycarbonate to allow viewing of the vertical bus bars  14  and inter connections. The vertical bus rearwalls  50  and the side isolation barriers  32  can also be fabricated from glass reinforced polyester sheet material, for example, GPO-2. 
   With the several modular insulation system  30  components installed, the vertical bus bars  14  are isolated both phase-to-phase and phase-to-ground. The back side of the mounting base  22  forms the front wall of the vertical bus compartment. The side isolation barriers  32  and the side barrier adapters coupled to the mounting base  22  form the outside sidewalls of the vertical bus compartment. The vertical bus rearwall  50  creates the rear wall and the inner isolation barriers  46  provide the internal phase isolation. Each phase, of the vertical bus  14 , is thereby enclosed in a separate, insulated vertical enclosure that creates an unobstructed vertical air duct or chimney to provide convection cooling for the vertical bus  14 . In the configurations where the vertical bus  14  is divided into two or more sections, a split bus barrier  70  is installed. In such case, the vertical bus rear wall  50  provides orifices  58  for ventilation to allow air to enter and exit above and below the split bus barrier  70  to preserve the chimney effect. In some installations, a vertical brace insulation covers  71  can be provided, as illustrated in  FIG. 11 . 
   One advantage of the modular insulation system  30  is that the only tool required to assemble or disassemble selected modular insulation system components is a screwdriver. Another advantage of the modular insulation system  30  is that repairs and maintenance of the various components can be accomplished from the rear side of the enclosure  10  without disassembling other components within the enclosure  10 . 
   For purposes of this disclosure, the term “coupled” means the joining of two components (electrical or mechanical) directly or indirectly to one another. Such joining may be stationary in nature or movable in nature. Such joining may be achieved with the two components (electrical or mechanical) and any additional intermediate members being integrally formed as a single unitary body with one another or with the two components or the two components and any additional member being attached to one another. Such joining may be permanent in nature or alternatively may be removable or releasable in nature 
   Thus, there is provided a modular system to insulate and isolate phase to phase vertical bus bars in an electrical equipment enclosure. The foregoing description of embodiments have been presented for purposes of illustration and description. It is not intended to be exhaustive nor to be limited to the precise forms disclosed and modifications and variations are possible in light of the above teachings or may be acquired by practice of the invention. The embodiments are chosen and described in order to explain the principles and practical application to enable one skilled in the art to utilize the modular insulation system in various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the modular insulation system be defined by the claims appended hereto and their equivalents.