Abstract:
An expandable transformer housing having a first housing member with a hollow cavity therein, a second housing member with a hollow cavity therein, and at least one exterior insert member therebetween in a stacked formation. The exterior insert member has a first end and a second end. A portion of the first end of the exterior insert member is adapted to engage the first housing member and a portion of the second end of the insert member is adapted to engage the second housing member. An interior insert member is also provided having a first end and a second end. A portion of the first end of the interior insert member is similarly adapted to engage the first housing member and a portion of the second end of the interior insert member is adapted to engage the second housing member. The interior insert provides insulation between the current source and the second windings of the transformer. The exterior and interior inserts are designed to expand the mounting depth of the transformer&#39;s enclosure to provide a stacked design in an interlocking manner.

Description:
TECHNICAL FIELD 
     The present invention relates generally to enclosures for encapsulating electrical transformers and, more particularly, to expandable enclosures for encapsulating various sizes of current transformers. 
     BACKGROUND OF THE INVENTION 
     Transformers are used extensively in electrical and electronic applications. Transformers are useful to step voltages up or down, to couple signal energy from one stage to another, and for impedance matching. Transformers are also useful for sensing current and powering electronic trip units for circuit interrupters such as circuit breakers and other electrical distribution devices. Other applications for transformers include magnetic circuits with solenoids and motor stators. Generally, a transformer consists of two or more windings (primary and secondary, etc . . . ) interlinked by a mutual magnetic field. As such, the transformer is used to transfer electric energy from one circuit to another circuit using magnetic induction. 
     Current transformers are used to monitor current flow in a circuit, such as to detect excessive power consumption and provide a warning signal or disconnect the power supply. The transformer must be protected from potential hazzards in its immediate environment with some type of sealing enclosure. Current transformers, as well as transformers in general, are shape and size specific to the end user&#39;s electrical needs and mounting specifications. Accordingly, this presents a unique challenge to designing and manufacturing a transformer and an enclosure therefor which delivers the required electrical performance with the required mounting specifications, all in the confines of a secure enclosure. 
     Various types of sealing enclosures are currently utilized to protect the transformer from the environment. One means for protecting transformers includes entirely sealing the transformer assembly with an epoxy resin. This is accomplished by pouring the epoxy resin into a molded container which houses the transformer to completely surround and encase the transformer coil with the epoxy resin. Epoxy is utilized because it prevents impact or vibrational shock from affecting the function of the transformer. However, several drawbacks are associated with epoxy encapsulated transformers: (1) using epoxy to encapsulate the transformer is a time consuming process, and (2) the use of epoxy prevents subsequent repairs to the transformer since the transformer is permanently encapsulated by the epoxy. 
     Another means for encapsulating transformers includes fastening two separate enclosures together. Typically, the enclosure comprises of two housinghalves which are connected by screws. As with an epoxy enclosure, this type of housing also has several drawbacks. One specific drawback is the increased capital investments in tooling required for each different enclosure. Typically, as the electrical specifications change for a specific transformer, the size of the transformer also changes. Accordingly, the enclosure for the transformer must also be modified. It is very common, however, for the change in transformer size to effect the depth of the transformer, and not the width or height. Thus, modifying the depth of a transformer requires modifying the mounting depth of the enclosure which results in the tooling of a new molded enclosure. The cost of new tooling is very expensive. 
     Accordingly, there is a need for an effective and efficient means for providing a protective enclosure for encapsulating various sizes of transformers, and specifically current transformers. Such an enclosure must not only provide all of the necessary safety features, but should also allow for quick assembly/disassembly of the enclosure and accessibility for repairs of the transformer. Additionally, the enclosure should eliminate the need for new tooling and additional capital expenditures for manufacturing a variety of sizes of transformer enclosures. 
     SUMMARY OF THE INVENTION 
     The transformer enclosure or housing of the present invention allows for the incremental expansion in mounting depth of the enclosure for a transformer without having to invest additional money in new tooling. The transformer enclosure of the present invention also allows for subsequent disassembly of the enclosure for repair of the transformer therein, as required. 
     According to one aspect of the present invention, the housing includes a first housing member, a second housing member, and an exterior insert member between the first and second housing members. The insert member has a first end and a second end. A portion of the first end of the insert member is adapted to engage the first housing member, and a portion of the second end of the insert member is adapted to engage the second housing member. The insert member comprises an exterior shell member which increases the length of the housing, and thus the interior volume of the housing, to allow the housing to accept larger transformers without manufacturing larger housing halves. 
     According to another aspect of the present invention, an aperture is provided through the center of the housing. An interior insert member is provided to bridge the gap adjacent the aperture, i.e., between the first and second housing members, similar to the exterior insert member. Like the exterior insert member, the interior insert member has a first end and a second end. A portion of the first end of the interior insert member is adapted to engage the first housing member adjacent the aperture therethrough, and a portion of the second end of the insert member is adapted to engage the second housing member adjacent the aperture therethrough. Like the exterior insert member, the interior insert member generally comprises an exterior shell member adjacent the aperture which increases the length of the aperture housing, and thus the interior volume of the housing, to allow the housing to accept larger transformers. Generally, the interior and exterior insert members have a height dimension that is substantially equal. 
     According to another aspect of the present invention, the first and second housing members, along with the interior and exterior insert members, have mating members which allow adjacent housing and insert members to engage and mate with one another in a stackable manner. In one of the preferred embodiments of the present invention, the mating members comprise an integral female recess, and an integral male lip or protrusion. Specifically, in a housing having a single interior and exterior insert: (1) the first housing member has an exterior male lip that depends from substantially the perimeter of an outer wall of the first housing member, and an interior male lip that depends from substantially the perimeter of the wall adjacent the aperture thereof; (2) the second housing member has an exterior female recess that depends from substantially the perimeter of an outer wall of the second housing member, and an interior female recess that depends from substantially the perimeter of the wall adjacent the aperture thereof; (3) the exterior insert has a female recess that depends from substantially the perimeter of the first end of the exterior insert, and a male lip that depends from substantially the perimeter of the second end of the exterior insert; and, (4) the interior insert has a female recess that depends from substantially the perimeter of the first end of the interior insert, and a male lip that depends from substantially the perimeter of the second end of the interior insert. As such, the respective male lips of the first housing member engage and mate with the respective female recess of the first end of each of the interior and exterior inserts, and the respective female recesses of the second housing member engage and mate with the respective male lip of the second end of each of the interior and exterior inserts, respectively. 
     According to another aspect of the present invention, a plurality of interior and exterior inserts are provided to sequentially expand the depth of the transformer housing. Each insert member has respective mating members substantially as described above. 
     According to another aspect of the present invention, the first and second housing members, along with the plurality of inserts therebetween, are fixed together to encapsulate the transformer therein. 
    
    
     Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings. 
     Brief Description of the Drawings 
     To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which: 
     FIG. 1 is a perspective view showing an expandable enclosure for a transformer housing according to the present invention; 
     FIG. 2 is an exploded perspective view of the expandable transformer enclosure of FIG. 1; 
     FIG. 3 is a cross-sectional view taken along line  3 - 3  of FIG. 1; 
     FIG. 4 is a cross-sectional view taken along line  4 - 4  of FIG. 2; and, 
     FIG. 5 is a cross-sectional view taken along line  5 - 5  of FIG.  2 ; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
     Referring now in detail to the Figures, and initially to FIGS. 1 and 2, there is shown an expandable housing  10  for a transformer (not shown). The expandable housing  10  is configured to surround and encase the transformer to protect the transformer from damage from the outside environment. The expandable housing  10  includes a first housing member  12 , a second housing member  14 , two exterior insert members  16 , 16   a  and two interior insert members  18 , 18   a . The interior insert members  16 , 16   a  and exterior insert members  18 , 18   a  are located between the first and second housing members  12 ,  14 . Each of the members  12 , 14 , 16 , 16   a , 18 , 18   a  are adapted to interconnect and engage or mate with adjacent members via interconnecting means in a stackable manner. Accordingly, if additional insert members ( 16  . . .  16   n ),( 18  . . .  18   n ) are required to expand the transformer housing  10 , such insert members are merely located between the first and second housing members  12 , 14  in an interconnected, engaging, and stacked manner, resulting in more separation between enclosure halves. The stacking of the inserts is only limited by the requirements on the depth of the mounting for the transformers. 
     The embodiment illustrated in the Figures has an aperture  20  extending from the first housing member  12  to the second housing member  14  which allows for current transformers. Specifically, the aperture  20  and the inner insert members  18 , 18   a  allow for a bus bar (not shown) or the primary and secondary windings (not shown) to pass through the aperture  20  in the housing members. The aperture  20  in the housing  10  provides insulation between the customer&#39;s current source and the secondary windings of the current transformer. 
     As shown in FIGS. 2 and 3, the first housing member  12  has a closed end  22  defined by a back wall  24  with an aperture  20  therethrough, and an open end  26  opposing the closed end  22 . An outer wall  28  depends from the back wall  24 , and a first exterior mating member  30  depends from a perimeter of the outer wall  28  adjacent the open end  26  thereof Additionally, an interior wall  32  depends from the back wall  24  and a first interior or inner mating member  34  depends from a perimeter of the interior wall  32  adjacent the aperture  20  of the first housing member  12 . The combination of the back wall  24 , outer wall  28 , and interior wall  32  defines a hollow cavity  35  in the housing member  12 . 
     Similarly, the second housing member  14  has a closed end  42  defined by a back wall  44  with an aperture  20  therethrough, and an open end  46  opposing the closed end  42 . An outer wall  48  depends from the back wall  44 , and a second exterior mating member  50  depends from a perimeter of the outer wall  48  adjacent the open end  46  thereof. Additionally, an interior wall  52  depends from the back wall  44  and a second interior or inner mating member  54  depends from a perimeter of the interior wall  52  adjacent the aperture  20  of the second housing member  14 . The combination of the back wall  44 , outer wall  48 , and interior wall  52  defines a hollow cavity  55  in the housing member  14 . 
     As illustrated in FIGS. 2-4, the first exterior insert member  16  and the second exterior insert member  16   a  are located between the first housing member  12  and the second housing member  14 . In this embodiment, with two exterior insert members  16 , 16   a , the first exterior insert member  16  is specifically located between and adjacent the first housing member  12  and the second exterior insert member  16   a , and the second exterior insert member  16   a  is specifically located between and adjacent the first exterior insert member  16  and the second housing member  14 . The first and second exterior insert members  16 , 16   a  each have a first end  56  and a second end  58  opposing the first end  56 . As shown in FIG. 4, first mating member  60  is adjacent the first end  56  of the exterior insert members  16 , 16   a , and a second mating member  62  is adjacent the second end  58  of the exterior insert members  16 , 16   a . As illustrated in FIGS. 2 and 3, the first mating member  60  of the first exterior insert member  16  is adapted to and is capable of engaging and mating with the first exterior mating member  30  of the first housing member  12 . The second mating member  62  of the first exterior insert member  16  is adapted to and is capable of engaging and mating with the first mating member  60  of the second exterior insert member  16   a . And, the second mating member  62  of the second exterior insert member  16   a  is adapted to and is capable of engaging and mating with the second exterior mating member  50  of the second housing member  14 . 
     Additionally, a first interior insert member  18  and a second interior insert member  18   a  are located between the first housing member  12  and the second housing member  14 . The interior insert members  18 , 18   a  are generally located within the confines of exterior insert members  16 , 16   a . In this embodiment with two interior insert members  18 , 18   a , best illustrated in FIGS. 2 and 3, the first interior insert member  18  is specifically located between the first housing member  12  and the second interior insert member  18   a , and the second interior insert member  18   a  is specifically located between the first interior insert member  18  and the second housing member  14 . As shown in FIG. 5, each of the first and second interior insert members  18 , 18   a , have a first mating member  64  adjacent a first end  66  thereof, and a second mating member  68  adjacent a second end  70  thereof. The first end  66  of each interior insert member  18 , 18   a  opposes the second end  70  of each interior insert member  18 , 18   a . As illustrated in FIG. 2, the first mating member  64  of the first interior insert member  18  is adapted to engage and mate with the first interior mating member  34  of the first housing member  12 . The second mating member  68  of the first interior insert member  18  is adapted to engage and mate with the first mating member  64  of the second interior insert member  18   a . And, the second mating member  68  of the second interior insert member  18   a  is adapted to engage and mate with the second interior mating member  54  of the second housing member  14 . 
     As such, the first housing member  12 , the first and second exterior and interior mating members  16 , 16   a ,  18 , 18   a , and the second housing member  14  are all connectable to form the stackable transformer housing  10  of the present invention. 
     For purposes of mating adjacent members, in the preferred embodiments each housing member  12 , 14  and insert member  16 , 16   a , 18 , 18   a  generally has a male mating means or a female mating means at one end thereof. In the preferred embodiments, as best shown in FIGS. 2-5, the first exterior mating member  30  of the first housing member  12  is a male means or a protrusion  30  extending from the perimeter of the outer wall  28  of the first housing member  12 , and the second exterior mating member  50  of the second housing member  14  is a female means or an indentation  50  adjacent the perimeter of the outer wall  48  of the second housing member  14 . Also as shown in FIGS. 2-5, the exterior insert members  16 , 16   a , and the interior insert members  18 , 18   a , have a male means or protrusion extending from one end thereof, generally the second end, and have a female means or indentation adjacent the other end thereof, generally the first end. 
     Further, the male mating member or means in the illustrated embodiment can also be identified as an integral lip about a perimeter of the end thereof, and the female mating member or means can also be identified as an integral recess adjacent the end thereof The male means, protrusion, or lip of any member identified herein is dimensioned to engage the female means, indentation, or recess of any adjacent member identified herein. In general, the male mating member of any component is capable of mating with the female mating member of any other component to form an encapsulating exterior portion of the transformer housing  10 . While the male mating means in the preferred embodiment is identified as a protrusion or lip and the female mating means in the preferred embodiment is identified as an indentation or recess, other mating means are also viable, including threaded means, gasket means, adhesives, mechanical fasteners, etc . . . . 
     As best shown in FIG. 3, (starting from the left most housing member  12  and continuing to the right most housing member  14  in FIG. 2) the male lip of the first exterior mating member  30  engages the female recess of the first mating member  60  of the first exterior insert member  16 ; the male lip of the first interior mating member  34  engages the female recess of the first mating member  64  of the first interior insert member  18 ; the male lip of the second mating member  62  of the first exterior insert member  16  engages the female recess of the first mating member  60  of the second exterior insert member  16   a ; the male lip of the second mating member  68  of the first interior insert member  18  engages the female recess of the first mating member  64  of the second interior insert member  18   a ; the male lip of the second mating member  62  of the second exterior insert member  16   a  engages the female recess of the second exterior mating member  50  of the second housing member  14 ; and, the male lip of the second mating member  68  of the second interior insert member  18   a  engages the female recess of the second interior mating member  54  of the second housing member  14 . The members are then drawn together, generally with the use of screws, and are then fixed together. 
     Each insert member, both interior and exterior, has a height dimension (H). Generally, the height dimension (H) of the exterior and interior insert members is substantially equal. Accordingly, with current transformers, for each exterior insert member  16  added to the expandable housing  10  an interior insert member  18  will also be required. Also, the height dimension of the first and second housing members  12 , 14  may be greater or less than the height dimension of the insert members  16 , 18 . 
     The above described housing components and mating elements thereof allow for a transformer housing  10  including: (1) a first housing member  12  and a second housing member  14  only, and no insert members; (2) one pair of mating members  16 , 18  between first and second housing members  12 , 14 ; (3) two pair of mating members  16 , 16   a ,  18 , 18   a  between first and second housing members  12 , 14 ; (4) three pair of mating members  16 , 16   a , 16   b , 18 , 18   a , 18   b  between first and second housing members  12 , 14 ; and so on and so forth, etc . . . . 
     Additionally, it is understood that with certain transformers, interior insert members and apertures through the back wall of the housing members are not required. In such instances, if the housing  10  is required to be expanded to contain a larger transformer, additional exterior insert members  16  are merely inserted and mated between the first and second housing members  12 , 14 . In the embodiment wherein no mating members are utilized the first exterior mating member  30  of the first housing member  12  mates with the second exterior mating member  50  of the second housing member  14 , and the first interior mating member  34  of the first housing member  12  mates with the second interior mating member  54  of the second housing member  14 . 
     When all components of the transformer housing  10  have been mated together in the above stated manner, the enclosure  10  is sealed. Generally, screws Is  15  placed in a tapped hole of the housing complete the securement of the housing. Then, wire terminals (not shown) are connected to the housing, fixed in place, and external wire leads are connected to the final transformer enclosure assembly. Finally, the transformer housing  10  is mounted with mounting fixtures placed through the mounting holes  72  in the housing  10 . 
     In the embodiments disclosed the first housing member  12  is shown to have male mating members  30 , 34 , and the second housing member  14  is shown to have female mating members  50 , 54 . It is possible, however, that the mating members of the first housing member  12  may possess female characteristics, and the mating members of the second housing member  14  may possess male characteristics. Additionally, both the first housing member  12  and the second housing member  14  may contain all male mating members or all female mating members as long as the insert members  16 , 18  have the appropriate corresponding mating members. 
     While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.