US1955468A - Electric conductor cable - Google Patents

Description

.April 17, 1934. M, E. NOYES yELECTRIC CONDUCTOR CABLE INVENTOR QGOMW Patented Apr. 17, 1934 UNITED STATES PATENT oFFlcE ELECTRIC CONDUCTOR CABLE Application February 26,1930, Serial No. 431,458

3 Claims.

This invention pertains to electric conductors, and relates more particularly to cable-like conductors of the type employed in overhead power lines of high voltage transmission systems.

It is well known that conductors employed for uses of this character are rendered relatively inefficient in operation, due to excessive power losses, if they have insuicient outside surface area. Among the most important of these losses are the corona losses which occur in the form of static discharges at the surface of the conductor when the potential gradient at that point exceeds a critical limit determined by various well known factors, and the excessive energy loss incurred by reason of the rise in temperature and resistance of the conductor when it has insuillcient radiating capacity to radiate the heat produced by the' current. As is well known, both of these losses may be eliminated, or atleast reduced to a minimum, by providing the conductor with suflicient outside surface area to give it the necessary radiating capacity and to reduce the potential gradient to a sufficiently limited value to overcome the corona effect.

For these reasons, as well as to provide for what is known as the skin effect of alternating currents, conductors of this type are made with relatively large diameters as compared to the diameters of the cross sectional areas of the current conducting material contained in them.

In addition to the requirement that they have a comparatively large surface area, it is also essential that these conductors be flexible, and that they have suilcient tensile strength to support both their own weight and the weather loads imposed upon them in service. Furthermore, they must be sufficiently resistant to compressive strains to prevent their being crushed by the relatively excessive transverse forces to which they are frequently subjected in service. They must also be of sufficiently simple construction to permitA their being manufactured at a practical cost.

The primary object of this invention is to provide a new and improved cable ofl the above described character which satisfies the abovementioned requirements, which is comparatively light in weight, of simple flexible construction, and capable of withstanding relatively high tensional and compressive strains.

Another object is to provide an improved form of cable of this character which may be manufactured at a relatively low cost.

These and other objects, as well as the novel features and advantages of the invention, will become more apparent when the following detailed description is read in conjunction with the accompanying drawing, of which Fig. 1 is a side view of a conductor cable constructed in accordance with the invention, showing a portion of it with the current conducting covering removed; G0 Fig. 2 a sectional View taken on the line II-II of Fig. 1; and Fig. 3 a cross-sectional View f a modilied form of spacer member.

Referring now to the drawing, the invention is illustrated as being embodied in a conductor comprising a centrally located core or tension member l of high tensile strength, which in its preferred form is a stranded flexible cable of galvanized steel, although a solid rod of steel or any other material may be used, as Well as stranded cables of other metals. If the core is not formed of a material which is itself resistant to corrosion, it is preferably coated or otherwise protected against corrosion. Because the core functions primarily as a tension member of the cable, and not as a current conductor, its conductivity is not of importance, and it need be made of only sufficiently large diameter` to provide the cable with the tensile strength required in addition to that afforded by the conducting material em- 30 ployed in the cable.

For so increasing the diameter of the cable over that of core l as to provide it with the necessary outside surface area to eliminate the aforementioned power losses, a spacer member 2 is 85 utilized. This member, which may be made of either conducting or non-conducting material, preferably the former, comprises a continuous strip of suitable cross-sectional form wound helically upon the core. For preserving the flexibility of the cable, as well as for increasing its life and reducing its weight as much as possible, this spacer member is preferably made of skeleton shape, the particular advantage of which will appear hereinafter. In addition, it is wound in an openly coiled fashion upon core 1, sufficient space being allowed between the adjacent turns to eliminate friction between them and to permit the cable to be flexed or bent with relative ease. However, the adjacent coils are placed suillciently close to each other to render the spacer capable of properly supporting a covering 3 of current conducting material which is mounted on the cable, as well as to provide it with the necessary resistance to compressive strains. To further reduce the weight of the cable, the spacer member is preferably made of some suitable strong light material such as aluminum or aluminum alloys.

The important requirements of the spacer 1'10 I member are that it have sufficient depth to give the conductor the necessary diameter, and sufficient ductility to hug the core tightly when wound helically upon it, and that it be sufficiently resistant to compressive forces to properly support the conductor and prevent the cable from collapsing when subjected to excessive crushing forces such as are encountered in service, sufficiently narrow at its base to not impair the flexibility of the cable and that it have suilicient bearing surface on its outer face to prevent the conductor supported by it being unduly worn away. These requirements are all met by spacer members of the forms shown in Figs. l and 3. As illustrated each comprises principally a web portion 4 and a flange portion 5, and is adapted to be tightly wound with relative ease upon the tension member forming the core of the cable with its web portion extending transversely of the core and its flange portion parallel to its axis. In a cable of this character, due to the pressure between the spacer member and the conductor covering supported by it, the softness of the material forming the conductors and the relative movement between such parts when the cable is flexed, it is highly important that suflicient bearing surface be provided between them to prevent the conductors from being prematurely worn away. This problem is solved by the skeleton form of spacer member shown without its being so thick at the point where it contacts with the core of the cable as to objectionably restrict the flexibility of the cable. Also, by reason of such construction, a substantial economy in spacer material, as well as a corresponding reduction in weight, is effected. In addition to the above-noted advantages, as will be readily appreciated a spacer of this form has the further advantage that it is relatively easy to coil upon the core as the flange portion on its outer face tends to support and hold the web portion in a position normal to the axis of the cable when the cable is being assembled. Of the two forms of spacer members shown, that in Fig. 1 has the advantage over that shown in Fig. 3 of a more evenly balanced outer bearing surface, while that shown in Fig. 3 is easier to manufacture and assemble, and for that reason, from a practical as well as economical standpoint, it is the preferable of the two forms.

While a certain portion of the current carried by the cable may pass through the core and spacer, it is nevertheless the primary duty of the conductor to function as such, and for that reason it is made of a material having a sufficiently high electric conductivity, and of sufcient cross sectional area, to function efliciently.

Although the conductor may be made in various forms, it preferably comprises one or more layers, depending upon the current carrying requirements, of stranded material of high current conductivity such as copper or aluminum preferably the latter because of its lightness in weight and other advantages. The strands of the conductor, while not essentially so arranged, are preferably wound helically upon the spacer, and in a direction opposite to although at a lesser pitch angle than, the spacer. By so winding the conductor, the spacer affords more support for it than if the conductor were wound in the same direction as the spacer.

As will be readily appreciated by those skilled in the art, because of the construction and arrangement of its members, the cable is highly resistant to compressive forces tending to crush it. Also, by virtue of the helical arrangement of the spacer, as well as of its other members, the cable is rendered sufficiently flexible to be bent with relative ease. Furthermore, because of its exceedingly simple form of construction the cable may be manufactured at a comparatively low cost.

According to the provisions of the patent statutes, I have explained the principle and operation of my invention, and have illustrated and described what I now consider to be its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. An electric conductor cable, comprising a flexible central core of high tensile strength, a spacer member having an inner web portion and an outer flange portion disposed at right angles to the web portion openly and helically wound upon said core with the web portion contacting the surface of the' core and the flange portion extending parallel thereto and forming a cylinderlike bearing surface of substantial area at a distance from said core, and a conductor covering of high current conductivity mounted on said bearing surface in a manner to hold said spacer member in place on said core.

2. An electric conductor cable comprising a flexible central core of high tensile strength, a T-shaped spacer member wound helically and openly on said core with its web or leg portion extending transversely to the axis thereof and its flange portion parallel thereto, whereby forming a cylinder-like bearing surface of substantial area concentrically spaced from said core, and a covering of high current conductivity mounted on the flange portion of said spacer in a manner to rmly hold i-t in parallel relation with the axis of said core. V

3. An electric conductor cable comprising a flexible central core of high tensile strength, an L-shaped spacer member wound in an open helical fashion upon said core with one of its legs bearing at its edge against the surface of said core and its other extending parallel with the surface of the core and forming thereby a cylindrical bearing surface of substantial area spaced from said core, and a flexible covering of high current conductivity mounted on the surface provided by'said spacer in a manner to maintain said spacer in proper alignment upon said core.

MAXWEIL E. NOYES.

iso

Images