US RE17296 E
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y 2 w. H. BASSETT Re. 17,296
HOLLOW CNDUCTOR Original Filed Oct. 3, 1924 nontoz %MLM/Mafi 5633572: 2331 & c temet; I,
eissued May 21; 1929.
UNITED STATES PATENT OFFICE.
WILLIAM E. ,BASSET'L OF CHESHIRE, CONNECTICUT, ASSIGNOR TO THE AMERICAN BRASS COMPAN Y, OF WATERBURY, CONNECTICUT, .A. COBPORATION OF CONNECTI- GUT.
' EOLLOW CONDUCTOB.
Original Re. 1,597,422, dated August 24 1926, Serial Ne. 741543, filed October 3, 1924. Reissue No. 17,156, dated December 11, 1928, Serial Ho. 19%,124 :lied May 17, 1927. This application !or reissuc filed February 14, 1929. Serial No. astma.
My invention relates to hollow conductors which are of relatively large diameter for a given cross-sectional area of the conduetng material so as to permit them to be used for high voltage transmission without substantial corona loss or for other purposes requiring maximum diameter and surface with reduced cross-section of conducting material, and has for its object to produce a new and improved hollow conductor of the required flexibility; high resistance to mechancal n- 'ury liable to result from crushing stresses, high tensile strength, maximum condueting efliciency and relatively low weight. My
improved conductor may be used bare or insulated as occasion requires.
Conductors heretofore made have been open to 'various objections. Thus, solid conductors of economic cross section when used for high voltage transinssion are of such small diameter that the corona losses are so great as to rendor the transmission relatively inefiicient, a disadvantage which numerous inventors have attempted to overcome by making the conductors hollow and thus in- *creasing the diameter of the conductors relatively to the cross-sectional area of the conducting material.
It has been proposed to make such hollow conductors in various ways, all which, however, have been found subject to certain disadvantages, which it is the present invention to obviate.
A cable embodying my invention is shown in the accompanying drawing-s, in which F ig. 1 shows a portion of the cable partly in side elevation and partly broken away;
Fig. 2 shows a transverse section of the same on the line 2-2 of Fig. 1;
Fig. 3 shows a portion of the strip on an enlarged scale; and
Fi 4: shows, on an enlarged scale, a modified orn of strip. 4
Referring more particularly to the drawings, 2 represents a twisted strip having at its edges lat'erally 'projecting portions or fianges forming thickened edges or head 4-4 so as to make it substantially I-shaped in cross-section. The outer surfaces G-6. of these heads are curved so as to substantially conform to the inner surfaces of wires or strands cabled thereon. The central part 8 purpose of my of the body portion of the strip nay be thickened so as to give the strip g'eater tensile strength as 'shown in Fig.'4. The twisted strip is twisted about its longitudinal axis, the preferable pitch being about one complete twist to four inc'hes for a strip five-eighths of an inch in width. A strip of such width whose body portion is .040 of an inch thick ao and whose edges are .090 of an inch thck gives satisfactor results.
About the' twisted strip, wires or strands 10 are cabled and if desired another layer of wires or strands 12, thus makin up the com- 35 pleted cable as shown. As s own in the drawings the wires or strands are round but obviously that form of wire or strand is not necessary to the embodiment of the invention. In forming the cable the strip in untwisted form with its p'rojecting fianges' is first produced. It is then twisted as shown and then 'ed to a cabling machine where it is surroundedwith one or more layers of conducting wires or strands thus producing the complote cable.
The thickened edges of the core are of especial importance in connection with the manufacture of the cable. Where a fiat strip w is used, the strip being twisted often suddenly changes from a spiral twist to a helical twist or curl which would continue for a foot or more before it could be stopped. In some cases in working with the fiat strip this has happened so often as to spoil the entire lot even for experimental purposes. A single spot where the twist has changed ffbm a. spiral form to a helical form runs the core for commerical purposes. When the strip oo has the fianges described heroin this difliculty is eliminated, andcores many miles in length can be made without dfects in the twist.
The use of two and maybe more layers of conducting wires or strands, and of different sizes, as in Fig. 2, has a special value in the production and use of the hollow style of cable. The metallic cross section is fixed by the requisite current carrying Capacity and the outside diameter is fixed by the required 0 voltage and the altitude of the line. By making the conductor in two layers, the flexibility of the cable is improved and by using wires of different sizes in two layers, the combination of the determined current carrying capacity or metallic cross section and required outside diameter can be more closely approximated under the conditions of operation.
It is aisoinportantto have a comparatively wide hearing of the inner conducting wires on the core. A better cable to meet all these required conditions can be designed by using a pluralty of layers, each layer made oi strauds which in turn consist ot several wires and the wires or strands in the cable being spiralled ,in the same direction or in different directions.
The flanges on the twisted strip constitute in effect a hollow spiral with e comparatively wide hearing face for the strands, the body portion constituting a comparatively narrow support extending hollow spiral; and the invention includes various other constructions than that specifically illustrated embdying the combination of hollow core and internal support.
Various other means than the flanges describedmay be 'used for stifl'cning the strip against longitudinel bendin and for thus opposing its changing from the desired spiral twist o a helical twist.
?he thickened edges of the core and the wires surrounding it, being located remote from the center of the cable, are thercfore located where they act most effectively for conducting current, as it is well known th ut 'alternating currenttends to be more desc es the distance froni the center of a eonductor is increased. T hus the metal in the core is so distributed that it acts efliciently as a conducting path as well as a supporting mem-ber.
The same type of hollow conductor is ad- Vantageous for other purposes requiring large diameter and surface with relativel small cross-section of conducting materia The major part of the conducting material, including the cabled wires and the flanges on the strip is distributed at the outer portions of the cable so that, when aiternating currents are used at frequencies which tend to concentrate the current toward the outside surface, the conducting material' is used efficiently. Moreover the amount of heat dissipated froni the hollow oonductor 'described is grcater than from a conductor of equal cross section of conducting material and smaller diameter. These considerations make the present conductor Very useful not only for high Voltages but also for carrying extra heavy currents which would be usually at comparatively low Voltages.
Vhile the core may be of the same material as the eonducting wires or strands cabled about it, it may be made of other suitable metal eiloy. I preferabiy in :ike the conducting strands br wires of copper alloy and make the twstml strip ot Copper or similar alloy. Such Copper or Copper alloys (which I refer to generically as cuprous metal) can be effecacross the interier of the tively worked and provide the necessary serength and Stress resisting eharacteristics. lVhere more th an one layer of wires or strands are used they may be spiralled in either` direction but 1 'prefer to (table the inner iayer around in e direction opposite to the twist of the strip and the succeeding layer in the same direction us the twist of the strip.
Various other nodifications may be made by those skilled in the art Without departing from the invention as defined in the following claims.
What I claim is: i
1. In a condueting cable comprising a series of strands cabled so as to form a tube, a core formed by a twisted strip having thickened conducting portions formin spiral surfaces engaged by said strands an supporting the same. u
2. In a conducting cable comprising a series of strands cabled core formed by a twisted strip having a body portion and projecting flanges forming thickened edges thereon, said fianges providing thickened conducting portions and` spital surfaces engaged by said strends and sup porting the same.
3.' 111 a conducting cable comprising a series of strands cabled so as to form a tube, a core formed of a twisted strip having a thin body portion and projecting flanges upon its edges so as to have an I-shaped cross-section, said flenges providing thickened conductin portions and spiral surfaces supporting sai strands.
4. In a conducting cable comprising a Series of strands cabld so as to form a tube, a core formed by a twisted stri having a body portion and projectng anges forming thickened edges thereon, said fianges providing thickened conducti ng portions and spiral sur-faces engaged by said strands and sup porting the same, said spiral surfaces being curved transversely so as to substantialiy conform to the inner surface of the tube.
5, In a conducting cable comprising a series of strands cabled so as to form a tube, a core formed by &twisted strip having a body portion and projecting flanges forning thickened edges thereon, said fianges providing thickened conducting portions and spirat surfaces engaged by said strands and supporting the same, said thickened conducting portions being about twice as thick as the adjacent body portion. u
6. A conducting cablc comprsing a series of strands cabled so as to form a tube and a core including a twisted strip and means for stiffening said strip against longitudinal bending.
7. In a eonducting Cable comprising a se ries of strands cabled so as to form a tube, a core tormed by a twisted strip having a body portion and projecting fianges, said fianges forning a comparatively wide-faced spiral so as to form a tube, a'
beiring for the cabled strands and said body portion forming a comparatively nar-ow transverse support.
8. A flexible conductor which is hollow so as to have a comparatvely large external surface withreduced metallic cross-section, said conductor comprising sti-amis cabled so as to form a tube, comparatively wide-faced spital hearing means for the internal surface of said tube of cabled strands and comparetively narrow supporting means extending diametricellyacross the space between opposite portions of said beat-mg means.
9. A flexible conductor which is hollow so as to have a comparatively large external surface with reduced metallic cross-section, said conductor comprising strands cabled so as to form a tube and artan ed in in a plurality of layers, the strands o the respective layers being of different sizes and bein of cup-ous v metale, comparatively wide-face spiralbearing means for the internal surface of said tube of cabled strnds'and comparatively narrow supporting means extendng diametrically 'across the space between opposite portions of said hearing means.
In witness whereof, I have hereunto signed my name.
DISCLAIMER Reissuu No. 17,296.-W21Z7'(m [1. Bassett, Cheshire, Umm. HULLOW (JoNnUc'ruk. atent dutecl May 21, 1929. Disclaimer filed March 13, 1931, by the assignoe, The American. Bmss C'mpany.
Ilcreby enters this disclaimer to claim 6 of said spocfication which is in the following words, to Wit:
A conducting cahlc comprising a series of strands cabled so as to form a tube and core including u twisted strip and means for stitl'cning said strip against longitudinal bendng.
[Ofiic'al Gazctte April 14, 1931.]