US3233198A

US3233198A - Hermetically sealed distribution transformer

Info

Publication number: US3233198A
Application number: US387125A
Authority: US
Inventors: Roger F Schrader; Wilmer H Airgood; Gordon C Nonken
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1964-08-03
Filing date: 1964-08-03
Publication date: 1966-02-01
Anticipated expiration: 1983-02-01
Also published as: ES315786A1

Description

Feb. 1, 1966 R. F. SCHRADER ETAL 3,233,193

HERMETICALLY SEALED DISTRIBUTION TRANSFORMER 2 Sheets-Sheet 1 Filed Aug. 5, 1964 d n 0 5 mm W. 1 n wm wmw 2M6 Feb. 1, 1966 R. F. SCHRADER ETAL 3,233,198

HERMETICALLY SEALED DISTRIBUTION TRANSFORMER 2 Sheets-Sheet 2 Filed Aug. 5, 1964 ,1 United States Patent-O 3,233,198 .HERMETICALLY SEALED DISTRIBUTION TRANSFURMER Roger F. Schrader, Wilmer H. Airgood, and Gordon C. Nonken, all of Pittsfield, Mass, assignors to General Electric Company, a corporation of New York Filed Aug. 3, 1964, Ser. No. 387,125 12 Claims. (CL 33694) This invention relates to distribution transformers and, more particularly, to hermetically sealed distribution transformers.

As is well known to those skilled in the transformer art, many failuresof distribution transformers, in use, -are due to the entrance of moisture and other contaminants into the sealed interior of the transformer. Many 'present-day transformers comprise a tank member into which is mounted the core and coil unit. A quantity of dielectric liquid is then placedin the tank and a cover mounted on the top thereof. The cover is usually sealed 'to the tank with some type of gasket by means of clampjing bands or clamping bolts. Also, as is well known, hand holes are usually provided in the coverto allow inspectionof the transformer interior without removing -the cover. Of course, the hand holes are also providedwith covers which are sealed to the main cover by a gasket and clamping bolts. While tankcover's and hand hole covers may be adequatelytested duringproduction for effective sealing, there is no practical means to test for effective sealing of these covers once the customer has removed either cover for inspection of the transformer. As a consequence, many transformers presently in use are not properly sealed. The lack of proper sealing allows moisture and other contaminants to enter, shortening the effective life of the transformer. The moisture and contaminants, in general, weaken the dielectric material of the transformer, suchthat the trans- ,former will fail when subjected to an otherwise harml'ess over"voltage. Ofcourse, as is well known, the

effect of moisture and other contaminants on the dielectric inaterial ofthe transformer causes progressive Weakening of such dielectric mater1al;

Another well-recognized problem in todays distribution transformer is the air pocket in the top of the transformer tanks As is well understood, the transformer tank is usually only filled part way with dielectric liquid having an air pocket in the upper portion of the transformer tank. This air pocket allows for the eX pansionof the liquid due to temperature changes during the operation of the transformer. However, the air pocket requires'that the transformer be constantly maintained in an upright position to prevent trapping of air bubbles in the electrical coil. As is well known, air

bubbles in the coil structure will often cause the transformer to fail during service.

It is therefore one object of this invention to provide an improved distribution transformer which is hermetically sealed.

size and lighter in weight than conventional transformers ofequivalent rating. In carrying out this invention in one preferred form, a novel, hermetically sealed, distribution transformer is provided, having a substantially form-fitting central housing which surrounds four sides of the transformer core spective bushings.

16. 45 :vided on the central portion 12, while a hanger bracket 3,233,198 Patented Feb. I, 1966 and coil unit. A pair of cooling flanges are hermetically attached to opposite sides of the central housing, closely conforming to the shape of the core and coil unit, thereby forming a hermetically sealed enclosure. High voltage bushings and low voltage bushings are hermetically sealed to the hermetically sealed enclosure. High and low voltage winding leads are internally connected to their re- The interior of the enclosure is completely filled with a dielectric cooling liquid.

The invention which is sought to be protected will be clearly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which its objects and advantages are obtained, as well as other objects and advantages thereof, will be more fully understood from the following detailed description of a preferred embodiment thereof, especially when considered in the'light of the accompanying drawings, in which:

FIGURE 1 is a perspective view of a hermetically sealed transformer according to a preferred form of the invention;

FIGURE 2 is a side view of the hermetically sealed transformer of FIG. 1; and

FIGURE 3 is an exploded perspective view of the hermetically sealed transformer of FIG. 1 showing a preferred form of construction thereof.

Reference will now be made to the drawings for a detailed description of the present preferred embodiment of this invention, in accordance with the patent statutes.

Like numerals will be used to indicate like parts throughout the various views thereof.

Referring first to FIG. 1 of the drawings, there is shown a perspective view of a preferred embodiment of the hermetically sealed transformer of this invention. As can be seen from FIG. 1, the hermetically sealed transformer 10 comprises a substantially four-sided, central portion 12 having

flange members

14 and 16 secured to opposite sides of the central portion 12. As can be seen the

flanges

14 and 16 are of greater extent than "the central portion 12. A pair of

high voltage bushings

18 and 20 are shown as mounted on flange 14, while a low voltage bushing 22 may be seen connected to flange In the usual manner, a lifting eye 24 may be pro- 26 may also be provided to facilitate the mounting of the transformer 10 on a pole in a manner Well understood by those skilled in this art.

FIGURE 2 shows in greaterdetail the internal construction of the transformer 10, while FIG. 3 shows, in

perspective view, the manner of constructing the preferred embodiment of the transformer. Referring first to FIG. 2 of the drawings, it may be seen that the transformer 10 is provided with a pair of

filling plugs

28 and 30, one plug being on flange 16 while the other plug is on flange 14. As will be well understood after the transformer 10 is completely assembled and hermetically sealed, a vacuum may "be pulled on one plug, for example, filling plug 28 while cooling dielectric liquid is fed into the interior of transformer 10 by means of the other filling plug 30. In this manner, as will be well understooththe entire interior of transformer 10 may become completely filled with the dielectric cooling liquid, such that no trapped air will be contained within transformer 10. Thus, as will be readily understood, the transformer 10 may be shipped in any convenient position, such as on its side orany other manner. The elimination of the air pocket also eliminates the need for the transformer to be constantly maintained in an upright position. Further, as will be appreciated the transformer 10 may be readily mounted on a pole while the .pole is lying on the ground; thus, enabling simpler mounting of the hermetically sealed transformer of this invention without requiring dangerous work at the top coil member.

of a pole. A ground clamp may be provided for transformer 10, such as ground clamp 31 shown as connected to flange 14.

Considering now FIG. 3 of the drawing, it may be seen that the central housing portion 12 is substantially a foursided, rectangularly shaped member in which is mounted the core and coil unit 32. Core and coil unit 32 may be firmly secured within housing 12, in any desired manner. As will be understood core and coil unit 32 will generally comprise a core member of oriented magnetic strip steel and will have mounted thereon at least one preformed Of course, it will be apparent that any conventional core and coil unit may be utilized in the transformer of this invention. As can be seen from FIG. 3, the central housing 12 conforms substantially to the shape of the core and coil unit 32, being substantially form-fitting with reference to the core and coil unit. The high voltage leads 34 and 35 may be brought out from the coil of core and coil member 32 through an insulated high voltage lead support 38 as shown. In a similar manner, the low voltage leads may be brought out from the coil of the core and coil unit 32.

Cooling flanges

14 and 16 are provided as hereinbefore specified on opposite ends of the central housing 12. As may be seen from FIG. 3 the high voltage flange 14 comprises an inner flange 4t) and an outer flange member 42. The inner flange member 40 is provided with a substantially rectangular-shaped opening which corresponds to the outer shape of the central housing 12 and is hermetically sealed to housing 12, preferably by means of Welding. The outer member 42 is provided with a pod-shaped portion, as shown, into which will fit the outer portion of the core and coil unit in the manner specifically indicated by FIG. 2 of the drawings. The outer member 42 is attached to the inner flange 40 hermetically such as, for example, by welding along the entire outer seam of the two flanges such as is indicated at 44 in FIGS. 1 and 2. High

voltage bushing members

18 and 20 are provided on 'the pod of member 42 in the manner indicated. Preferably the high voltage bushings will be cast of an epoxy resin material having integral studs, although it will be understood that they may be molded or cast with a cable lead extending therethrough. Preferably a metal mounting flange, such as 46 or 48, may be provided on the bushings, for example, being spun over the epoxy with a sealant provided and will be welded to the pod to provide a hermetic seal between the bushing and member 42. The high voltage leads 34 and 36 will be connected internally to the integral stud or cable lead of the

bushings

18 and 20 to provide the high voltage connection. It will be understood that other types of bushings may be used, if desired. The basic requirement is that each bushing be hermetically sealed to the housing. The number of bushings required will, of course, depend on the specific transformer.

The other flange 16, in a similar manner, is provided with the inner flange portion 50 and the outer flange 52. Outer flange 52 is provided with a pod-shaped portion as indicated, to conform to the opposite portion of the core and coil unit. In the same manner as flange 14, portion 50 of flange 16 has a central opening conforming to the shape of the central housing 12 and is hermetically sealed thereto such as, for example, by welding. The outer flange member 52 is hermetically sealed to inner flange 59 such as, for example, by welding as is indicated at '54 in FIGS. 1 and 2. The low voltage leads are brought to the low voltage bushings generally indicated by the numeral 22 in FIG. 3. In the preferred embodiment the low voltage bushings 22 are also cast of epoxy resin having an integral stud and may be cast directly'on a flange 50, if desired, thus providing the desired hermetical seal to the cooling flange 50. The integral stud cast in the bushing 22 will be connected to the low voltage leads internally in .a manner well understood by those skilled in the art. Again, it will be understood that any type of bushing m y be used, it only being necessary that such bushing be hermetically sealed to the transformer. The number of bushings required will depend on the transformer.

Of course, if desired the lifting eye 24 may be welded to the central portion 12 and the hanger bracket may be welded to the side of the central portion particularly in the manner indicated in FIGS. 1 and 2 of the drawings. After the transformer has been completely assembled, it will be understood that each opening, with the exception of the filling plugs 28 and 30, will be hermetically sealed, preferably by means of welding. The filling plugs 28 and 30 will be utilized to completely fill the interior of the transformer 10 with a dielectric cooling liquid and then each of the plugs may be hermetically sealed. For example, they may be welded closed or they may be provided with screw fittings which will completely seal the openings. In this manner there will be provided a hermetically sealed transformer 10 with the entire interior of the transformer completely filled with a dielectric cooling liquid. Of course, as will be understood, due to the form-fitting of the central portion 12 and the cooling flanges 1 4 and 16 the hermetically sealed transformer 10 will be substantially smaller and lighter than conventional transformers of similar ratings.

If it is a desirable to provide for small expansion of the liquid dielectric which completely fills the interior of the transformer 10 the

flanges

14 and 16 may be made of tthin gauge steel which will allow them to fiex under the pressure of the expanding liquid within transformer 10. Thus the small expansion of the liquid may be readily contained by the flexing of the

flanges

14 and 16 without the necessity for any air pockets within the transformer.

From the above it will be apparent that there has been provided a hermetically sealed distribution transformer which will fill all of the objects hereinbefore set forth.

Of course, it will be readily apparent to those skilled in the art that the specific details of construction andthe specific size and shapes of the various portions of the transformer while presently preferred are not required. It will be apparent to those skilled in the art that many variations and modifications may be made of the single embodiment disclosed. For example, it will be obvious that the high and low voltage bushings .could be mounted on the same cooling flange, if desired. They could also be hermetically sealed to the central portion. Of course, the cooling flanges could be the same size as the central portion, especially for low rated transformers. It is intended to include all such modifications and variations within the scope of the invention as it is defined in the appended claims.

What is claimed as new and which it is desired to secure by Letters Patent of the United States is:

1. A hermetically sealed distribution transformer comprising, in combination, a rectangular-shaped housing open at opposite ends, a core and coil unit having high and low voltage leads secured within said housing, a pair of cooling flanges of greater extent than said housing, said cooling flanges being welded to said open opposite ends of said housing to form a hermetically sealed enclosure including said flanges, at least one high voltage bushing hermetically sealed to one of said pair of cooling flanges and internally connected to said high voltage leads, low

voltage bushings hermetically sealed to the other of said cooling flanges being welded to said open opposite ends of said housing to form a hermetically sealed enclosure including said flanges, at least one high voltage bushing hermetically sealed to one of said pair of cooling flanges and internally connected to said high voltage leads, loW voltage bushings hermetically sealed to one of said pair of cooling flanges and internally connected to said low voltage leads, the interior of said hermetically sealed enclosure being completely filled with a dielectric cooling liquid.

3. A hermetically sealed distribution transformer comprising, in combination, a rectangular-shaped housing open at opposite ends, a core and coil unit having high and low voltage leads secured within said housing, a pair of cooling flanges of greater extent than said housing, said cooling flanges being welded to said open opposite ends of said housing to form a hermetically sealed enclosure including said flanges, at least one high voltage bushing and low voltage bushings hermetically sealed to said enclosure, said bushings being internally connected to said high and low voltage leads, the interior of said hermetically sealed enclosure being completely filled with a dielectric cooling liquid.

4. A hermetically sealed transformer comprising, in combination, a core and coil unit, said core and coil unit having high voltage and low voltage leads, a central housing portion surrounding and containing said core and coil unit on four sides, a pair of cooling flanges of greater extent than said central portion, said cooling flanges being welded to said central portion and completing a hermetic enclosure including said flanges about said core and coil unit, at least one high voltage bushing hermetically sealed to one of said pair of cooling flan es and being internally connected to said high voltage leads, low voltage bushings hermetically sealed to the other of said pair of cooling flanges and internally connected to said low voltage leads, filling plugs being provided in said cooling flanges and the interior of said hermetic enclosure being completely filled with a dielectric cooling liquid.

5. A hermetically sealed transformer comprising, in combination, a core and coil unit, said core and coil unit having high voltage and low voltage leads, a central housing portion surrounding and containing said core and coil unit on four sides, a pair of cooling flanges of greater extent than said central portion, said cooling flanges being welded to said central portion and completing a hermetic enclosure including said flanges about said core and coil unit, at least one high voltage bushing and low voltage bushings hermetically sealed to said enclosure, said bushings being internally connected to said high and low voltage leads, filling plugs provided in said enclosure and the interior of said hermetic enclosure being completely filled With a dielectric cooling liquid.

6. A heremetically sealed transformer comprising, in combination, a core and coil unit, said core and coil unit having high voltage and low voltage leads, a central housing portion surrounding and containing said core and coil unit on four sides, a pair of cooling flanges of greater extent than said central portion, said cooling flanges being Welded to said central portion and completing a hermetic enclosure including said flanges about said core and coil unit, high and low voltage bushings hermetically sealed to at least one of said pair of cooling flanges and being internally connected to said high and low voltage leads, filling plugs provided in at least one of said cooling flanges and the interior of said hermetic enclosure being completely filled with a dielectric cooling liquid.

7. A hermetically sealed distribution transformer comprising, in combination, a substantially rectangular-shaped housing open at opposite ends, a core and coil unit having high voltage and low voltage leads secured within said housing, said housing being substantially form-fitting with respect to said core and coil unit, a pair of cooling flanges of greater extent than said housing, said cooling flanges being welded to said open opposite ends of said housing to form a hermetically sealed enclosure including said flanges, each of said cooling flanges being provided with a pod portion to substantially conform to the shape of said core and coil unit, at least one high voltage bushing hermetically sealed to one of said pair of cooling flanges and internally connected to said high voltage leads, low voltage bushings hermetically sealed to the other of said pair of cooling flanges and internally connected to said low voltage leads, the interior of said hermetically sealed enclosure completely filled with a dielectric cooling fluid.

8. A hermetically sealed distribution transformer as claimed in claim 7 in which said cooling flanges are made of thin gauge metal to allow for flexing during the expansion of said cooling fluid within said transformer.

9. A hermetically sealed distribution transformer comprising, in combination, a substantially rectangular-shaped housing open at opposite ends, a core and coil unit having high voltage and low voltage leads secured within said housing, said housing being substantially form-fitting with respect to said core and coil unit, a pair of cooling flanges of greater extent than said housing, said cooling flanges being welded to said open opposite ends of said housing to form a hermetically sealed enclosure including said flanges, each of said cooling flanges being provided with a pod portion to substantially conform to the shape of said core and coil unit, high and low voltage bus rings hermetically sealed to said hermetically sealed enclosure and internally connected to said high and low voltage leads, he interior of said hermetically sealed enclosure completely filled with a dielectric cooling fluid.

10. A hermetically sealed distribution transformer comprising, in combination, a core and coil unit, high and low voltage leads extending from the coil of said core and coil unit, a hermetic enclosure about said core and coil unit, said hermetic enclosure comprising a central portion surrounding four sides of said core and coil unit and flange members on opposite sides of said central portion of greater extent than said central portion and hermetically sealed thereto to complete said hermetic enclosure including said flanges, high and low voltage bushings hermetically sealed to said enclosure and internally connected to said high and low voltage leads, and the interior of said hermetic enclosure completely filled with a dielectric fluid.

11. A hermetically sealed transformer as claimed in claim 10 in which said flange members are made of thin gauge metal which will flex to contain expansion of said dielectric fluid.

12. A hermetically sealed distribution transformer comprising, in combination, a substantially rectangular shaped housing open at opposite ends, a core and coil unit having high voltage and low voltage leads secured Within said housing, said housing being substantially form-fitting with respect to said core and coil unit, a pair of cooling flanges of greater extent than said housing, said cooling flanges being welded to said open opposite ends of said housing to form a hermetically sealed enclosure including said flanges, each of said cooling flanges being provided with a pod portion to substantially conform to the shape of said core and coil unit, high and low voltage bushings, hermetically sealed to said hermetically sealed enclosure and internally connected to said high and low voltage leads, at least one filling plug provided in said sealed enclosure, the interior of said hermetically sealed encosure completely filled with a dielectric cooling fluid.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.