Патент USA US2411656код для вставки
Nov- 26, 1946. K. L. HENDERSON ET AL 2,411,856 COAXIAL BUSHING Filed Feb. 7, 1944 JNVENTQRS Patented Nov. 26_, 1946 2,411,656 UNITED_'STATES PATENT OFFICE 2,411,656 COAXIAL BUSHING Kenneth IL. Henderson and Edward F. lDe Mers, Irondequoit, N. Y., assignors to Stromberg Carlson Company, Rochester, N. Y., a corpora tion of New York Application February 7, l91f4, Serial No. 521,463 3 Claims. 1 (Cl. 174-73) 2 This invention relates to insulating bushings nected to the other conductor B3 of the bushing especially adapted for use in connection with as will appear later. high voltage apparatus. The bushing 5 has the central metal conductor or stem l3 (just mentioned) which is provided at its lower end with a threaded portion and is provided at its upper end with a mushroom-like metal cap M having a screw terminal l?. As il lustrated, the upper end portion of the stem is In certain high voltage devices such as in an oil-immersed transformer, it is essential that two output conductors thereof be extended through the wall of the transformer to suitable terminals, in a way that will prevent oil leak age and yet will insure that there Will be no volt knurled so that when it is forced into the open age breakdown or corona effects between the 10 ing in the cap, a close ?t results and the joint several parts. v The present invention has for its main purpose the production of a coaxial bushing which will satisfy the mentioned requirements and in ad dition will be sturdy in construction as well as 15 especially compact in design. The various features and advantages of the between these parts can be sealed by soldering or brazing. The stem is enclosed by a paper or other insulating sleeve lt extending from the inner surface of the cap M to the threaded lower portion of the stem. The other conductor lt (previously mentioned) of the bushing comprises a brass tube which surrounds the paper sleeve invention will appear from the detailed descrip E6, with the stem l3 enclosed therein. Thus, the two conductors iS and BB are concentrically ar tion and claims when takenV with the drawing in which: ,_ 20 ranged with respect to each other. The tube lß Fig. l illustrates a side elevation of the coaxial has its upper end fusibly joined in concentric bushing of the present invention, together with relation to the inner border of an annular disc a fragment of an oil-?lled transformer on which 20, so that the disc extends perpendicular to the axis of the tube. This disc is provided With an it is mounted, the transformer units being di agrammatically illustrated; 25 integral ferrule fi having a screw terminal 22. Fig. 2 is a longitudinal section through the This ferrule tapers in the direction of the cap, > bushing; and the outer edge of the disc being connected to an intermediate portion of the inner surface of the Fig. 3 is a cross-sectional view of the bushing ferrule, to provide a recess at each surface of the taken on the line 3-3 of Fig. 2. Referring especially to Fig. 1, the numeral ä 30 disc. generally designates the coaxial insulating bush The cap M and the ferrule ?l are insulated from each other by a porcelain sleeve or insulator ing of the present invention, having its lower portion extending through an opening in the 24. This insulator, With asbestos washers 25 and top of an oil-?lled metal transformer case li. 26 engaging its respective ends, surrounds the Within this case there are mounted the oil-im 35 stem l3 and the enclosing paper tube M3. It will mersed transformer units 8 and 9. The primary be seen that the upper end of the insulator ex windings of these transformers are connected in tends into the recess at the under side of the cap, multiple to the conductors ll and |2 which re while the lower end thereof extends into the re spectively lead to a low voltage supply, such as cess at the upper part of the ferrule. Since hot a hundred ten volt alternating current source. 40 oil tends to seep through any mechanical joint, These conductors pass through spaced openings it is essential that such a joint be avoided at any part of the bushing. On the other hand, solder or other fused metal will not adhere to glazed ?bre and screw terminals having a suitable ad porcelain when untreated. In this construction, hesive such as *'Glyptal" applied to the joints be 45 however, bands 28 and 29 of the porcelain glaze tween the several parts. The secondary Wind at the respective ends of this insulator are ing of the high voltage transformer unit 8 has metallized by having a thin ñlm of metal fused one terminal conductively connected to the case or sputtered into the glaze at these portions. The 6 as by means of solder and has its other termi unoccupied portion of the recess in the cap is nal conductively connected through terminal 44, 50 fllled with molten solder 3| while the unit is held to one conductor 18 of the bushing 5. This con inverted from the position illustrated. This ductor of the bushing is also connected in mul solder becomes fused to the cap and to the metal tiple to one terminal of the secondary winding lized band 28 of the insulator 24, thereby provid of the low voltage transformer 9. The remain ing an oil-proof seal at this joint. Similarly, the ing terminal of this winding is conductively con 55 un?lled portion of the recess in the top of the in the bottom of the transformer case where they aresealed against oil leakage by well-known 2,4i1,858 ferrule 2| is ?lled with molten solder 82, while the unit is held in theA upright position shown. This solder likewise becomes fused to the ferrule and to the metallized band 29 on the insulator thereby affording an oil-proof seal at this sec ond location. It should be noted that the ?llets 4 in a position to encircle the insulator. The diam eters of these rings are such that they project beyond the adjacent sharp edges 42 and 56 (Fig. 2) of the mentioned ?llets. The coaxial bushing is pai'ticularly applicable where two conductors, such as |3 and |8, both 3| and 32 of solder taper to sharp edges at 33 at high potential with respect to a case but at and 34 at the boundaries between the metallized low potential with respect to each other, .are to bands and the adjacent insulator portion, i. e., be brought through the case. where they merge with the outer surface of the 10 While the invention has been illustrated with insulator. The thin edges of solder at the men two conductors extending from within the case tioned points tend to reduce the strain and there 6, through the insulator 38, it also includes an _by reduce the danger of fracture of the porcelain arrangement wherein but a single conductor ex v insulator resulting from the unequal rate of ex tends through the mentioned insulator. Also, the pansion and contraction of porcelain and solder. 15 invention has been particularly described with The part of the hollow conducting tube |8 reference to an oil-sealed device but it is equally which extends from the ferrule to almost the applicable to any fluid-sealed electrical device lower end of the assembly, is enclosed by a sec where the the lfluid may be air at any predeter ond porcelain sleeve or insulator 3B, an asbestos mined pressure, nitrogen or the like. washer 31 being placed between .the upper end 20 The terms porcelain and ceramic, as used here of the insulator and the under surface of the disc in, are intended to include those materials pos 20. A band-like portion at the upper .part of the sessing good insulating properties and having a outer surface of the insulator as well as the top vitreous surface. edge and the entire inner surface of the insulator What we claim is: are provided with a continuous metallized ?lm of 25 1. A coaxial bushing for use with a ?uid-?lled the character mentioned, as indicated at 38, 39 and 40. Molten solder 4| is used to ?ll the re receptacle of an electricaldevice, said bushing cess in the under 'part of the ferrule and to make a fused joint between the ferrule and the metal ductor extending through said hollow conductor comprising a hollow conductor, a second con in insulated relation thereto, each conductor ter lized band 38. In this instance also, the solder 30 minating in an annular terminal, a hollow ce is caused to thin out to a sharp edge 42 at its ramic insulator enclosing one of said conductors junction with porcelain insulator, for the reason and spacing said terminals, band-like surface given above. It should be mentioned that the areas of said insulator encircling both end por metallized layer at 39 and 40, which covers the tions thereof being metallized, fused metal con-g end and the inner surface of the insulator 36, 35 nections sealing each terminal to an adjacent is conductively connected to the ferrule 2| metallized band, a second ceramic insulator en through the layer at 38 and' through the solder closing said conductors, spaced band-like surface in contact therewith. The construction `just de areas of said second insulator encircling the same scribed substantially eliminates any corona effect being metallized, a fused metal connection seal between the inner surface of the insulator 36 and 40 ing one of said metallized areas to the terminal the adjacent parts. › of the hollow conductor, a metal ring encircling The lower end of the insulator is engaged by said last-mentioned insulator and adapted to 'be an asbestos washer 43 through which the con metal sealed to the margin of the wall of the ductor tube |8 is inserted. An annular, metal ter receptacle de?nin'g an opening therein, and a minal 44 which snugly contacts 'the lower surface 45 fused metal connection sealing said ring to the of .the asbestos washer 43, is soldered on the tube remaining band-like metallized area of said sec |8 as indicated at 45. An insulating collar 4B ond in-sulator, certain of said metal connections is next assembled over the lower end of the tube having relatively thick portions tapering to thin |8 as well as over the threaded portion of the edges at the boundaries between the several met stem |3 where a lock washer 41 and a nut 48 50 allized hands and the adjacent insulator portion. tightly hold the .parts in assembled relation as 2|. A coaxial bushing for use with a ?uid-?lled indicated. The washer 41| and nut 48 are dipped into molten solder to provide soldered joints as indicated at points 49 and 50. Since .the bushing must make an oil-.tight seal receptacle of an electrical device, said bushing comprising a hollow conductor, a second con ductor extending through said hollow conductor in insulated relation thereto, each conductor ter with the transformer casing, fprovision must be minating in an annular terminal, a hollow ce made to solder these parts together. To this end, ramic insulator enclosing one of said conductors the outer surface of the insulator sleeve is pro and spacing said terminals, band-like surface vided with a metallized band 52 at an interme diate point thereon. To this band there is sealed 60 areas of said insulator encircling both end por tions thereof being metallized, fused metal con as by solder 53, the inner part of an inverted nections sealing each terminal to an adjacent channel-shaped ring or apron 54 which encircles metallized band, a second' ceramic insulator en the insulator. The outer edge of this apron is closing said conductors, spaced band-like sur soldered, as indicated at 55, to that portion of the face areas of said second insulator encircling the top of the transformer case 8 surroundingthe same being metallized, a fused metal connection opening therein. sealing one of said metallized areas to the ter It will be noted that the ?llet of solder 53 tapers minal of the hollow conductor, a metal ring en to a thin edge 58. This sharp edge is directed circling said last-mentioned insulator and adapt toward the sharp edge 42 of the ?llet of solder ß i. to be metal sealed to the margin of the wall With a great difference in potential lbetween the 70 ed of the receptacle de?ning an opening therein, a apron 54 and the ferrule 2 |, |the respective sharp fused metal connection sealing said ring to the edges 5B and 42 thereof would promotecorona remaining band-like metallized area of said sec discharge effects. In order to avoid such effects, ond insulator, the fused connections related to the ?llets of solder 4| and 53 have metal ríngs said second insulator having relatively thick por 51, 51, of circular cross section, soldered thereto 75 tions tapering to thin edges directed toward each 2,411,e5e 5 other, and a ring of curved cross section individual to each of said last-mentioned connections and minal of the hollow conductor, a substantial por tion of the inner surface of said second in conductively connected thereto, said rings en sulator being provided with an electrically con circling said second insulator and projecting .'e ducting coating conductively connected to the yond the thin edges of their related connections. UI terminal of the hollow conductor, a metal ring 3. A coaxial bushing for use with a fluid-?lled encircling said last-mentioned insulator and receptacle of an electrical device, said bushing adapted to be metal sealed to the margín of the comprising a hollow conductor, a second con wall of the receptacle de?ning an opening there ductor extending through said hollow conductor in, a fused metal connection sealing said ring to in insulated relation thereto, each conductor ter 10 the remaining band-like metallized area of said minating in an annular terminal, a hollow ce second insulator, the fused connections related to ramic insulator enclosing one of said conductors said second insulator having relatively thick por and spacing said terminals, band-like surface tions tapering to thin edges directed toward each areas of said insulator encircling both end por other, and a ring of curved cross section in tions thereof being metallized, fused metal con 15 dividual to each of said last-mentioned connec nections sealing each terminal to an adjacent tions and conductively connected thereto, said metallized band, a second ceramic insulator en rings encircling said second insulator and pro closing said conductors, spaced band-like surface jecting beyond the thín edges of their related con areas of said second insulator encircling the nections. same being metallized, a fused metal connection 20 KENNE'I'H L. HENDERSON. sealing one of said metallized areas to the ter EDWARD F. DE MERS.