Inductor devices – With outer casing or housing
Reexamination Certificate
1999-06-09
2001-05-29
Mai, Anh (Department: 2832)
Inductor devices
With outer casing or housing
C336S092000
Reexamination Certificate
active
06239682
ABSTRACT:
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'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 m
Femal Michael J.
Golden Larry I.
Mai Anh
Square D Company
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