US3193616A - Corona reducing armor rods - Google Patents

Description

y 1965 s. N. SCHLEIN 3,193,616

CORONA REDUCING ARMOR RODS Filed July 12, 1963 2 Sheets-Sheet 1 Fig.3

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' CORONA REDUCING ARMOR RODS Filed July 12, 1963 2 Sheets-Sheet 2 INVENTOR. sfiYflouk. N. SCHLEM kUW N ATToRNeY United States Patent 3,193,616 CORONA REDUCING ARMOR RODS Seymour N. Schlein, University Heights, Ohio, asslgnor to The Runner Manufacturing Company, a Division of Tcxtron, Inc., Cleveland, Ohio, a corporation of Rhode Island Filed July 12, 1963, Ser. No. 294,609 5 Claims. (Cl. 174-127) This invention relates to improvements in armoring for high voltage conductors and more particularly to a means for reducing corona discharge and damage from the armoring to the conductor.

As is well known, it has become common practice to provide devices, known as armor rods which are applied to conductors for the purpose of reinforcement. Such devices are'shown and described in Patents Nos. 2,587,521 and 3,087,008.

When such devices are used in conjunction with high voltage transmission lines, a problem arises in that at the sharp ends of such rods there is a concentration of the electrical field which causes an ionization of the air in the immediate vicinity and a resultant brush discharge, commonly known as corona discharge. Corona discharge represents a loss of power, the creation of ozone in the vicinity of the conductor and a resultant deterioration of the conductor, and causes static which interferes with communications.

Various expedients have been suggested for the elimination of this corona, one of which is disclosed in my copending application Serial No. 346,670, filed December 20, 1962, and contemplates the provision of a ring on the end of one of the rods which extends outward in spaced relation surrounding the line. Still other means contemplates the use of attachments which are secured to the end of the rods to provide an increased distribution of the field outwardly of the line.

. All of these devices increase the cost of the installation.

Although some of the devices, such as shown in Patent No. 3,087,008, do not materially increase the cost of the installation, they have the disadvantage that at the extreme end of the rod, where the outer surface merges with the inner diameter of the helix, there is provided a sharp knife edge or point. This knife edge has the disadvantage that great care must be observed during the installation and removal of the rods, or the point will cause the outer wires of the line to which it is attached to be nicked by the points. This nicking defeats the purpose of shaping the ends because the nicking provides sharp spicules which cause the generation of corona.

In addition, the sharp points bear against the outer surface of the line and the vibration of the line causes a working of the points on the line which frets the line and in time causes a wear or sharpening of the points which leaves a sharp knife edge on the extremities that is spaced from the line and increases instead of decreases the corona.

Furthermore the points which are on the ends of the rods are apt to become damaged during shipment as well as damaged during installation, due to the fact that they are small, needle-like and subsequently somewhat fragile. Even though the rods are normally made of a hard drawn resilient material, they can be bent very easily and thus are worse than the ordinary rounded or ball end rods.

In the larger of the transmission lines, where the lines carry very high voltages, such'rods may have a rod diameter from A to /2" and sometimes even larger. In the interest of reducing the weight and in economizing in material it is possible to make such rods of a tubular stock. With such tubular stock it would be even more difficult to provide an end formation which has the desired configuration. Normally the rods are made of solid stock.

Further such ends, when made of tubular stock, if damaged, provide leakers into which moisture may enter, eventually providing a sufficient accumulation that in cold weather it can freeze and cause the rods to split. This would leave sharp edges, both at the point where the moisture enters and the place where the rod splits.

The present invention contemplates the provision of an armor rod which may be put to all the uses normally made of armor rods and wherein the end is provided with an improved formation which greatly reduces the defects of the prior art delineated above.

Still otheradvantages of the invention and the invention itself will become more apparent from the following description of an embodiment thereof, which description is illustrated by the accompanying drawings and forms a part of this specification.

In the drawings:

FIG. 1 is a fragmentary elevational view of a set of armor rods, showing the manner of their application to a line which is shown in dotted lines; 7

FIG. 2 is a view taken from the line 2-2 of FIG. 1, with the position of the line shown as a solid section;

FIG. 3 is an enlarged end view of a single rod;

FIG. 4 is an enlarged fragmentary view of the end portion of a rod taken from the outside; and

. FIGS. 5 and 6 are similar views taken at and from that of FIG. 4.

In the drawings like parts have been designated by like reference characters.

Briefly, my invention contemplates an armor rod, solid or hollow, which is formed of hard, resilient material, in the form of an open helix capable of being applied to a line from its side without permanent deformation of the rod. Preferably the helix is formed with an inside diameter slightly less than that of the line and a pitch that is slightly shorter than the pitch of the line, although it may be longer. The end ofthe rod is provided with an outer portion which curves toward the inner diameter of the helix and an inner surface which curves outwardly toward the outer diameter of the helix, the two surfaces meeting in a spatulateend zone which is curved transversely to the axis of the helix.

More specifically, as shown in FIG. 1, a plurality of rods 10 are provided, being shown in place on a conductor 11. The rods preferably are designed to provide a complete sheath surrounding the conductor, although commercially it has been found that good results are obtained even if the sheath is not complete. A slight gap is desirable because in this instance it can be assured that the rods engage with the conductor tightly which they could not do if the rods were large enough so that their combined diameters at their point of tangency was greater than the circle at that point around the conductor.

As can be seen from FIGS. 1 to 3, the extremities of the rods are provided with spatulate ends 12. These ends, as viewed from the outer side of the helix, may be curved on a radius equal to the diameter of the rod, straight, or, flattened in a Zone on opposite sides of the center of the rod with a curvature toward the ends, the last being illus trated in FIG. 1.

As best shown in FIG. 2, it is preferred that, as viewed from the ends, these extremities 12 be slightly curved so that these surfaces on the ends when installed on a line have a curvature on a radius equal to that of the inside of the helix plus the distance from the inner diameter of the helix to the center of the surface 12. When so made, they would all lie in a circle having slight interruptions between the rods, as viewed in FIG. 1. If the ends were straight, as viewed from the outside of the helix and curved as viewed from the ends, there would be no interruption and they would form a continuous ring on the end. In addition, if they where straight as viewed from the end, they could form a polygon.

Of particular importance is the formation of the outer and inner surfaces at the ends, which surfaces extend from the inner and outer periphery of the rod to the end zone 12.

As best illustrated in FIGS. 4 and 5, the outer surface starts at a point 14a and gradually curves downward to the end 12. This curvature should preferably be on a radius at least equal to the radius defining the outer diameter of the helix, although it does not necessarily have to be a true arc. Crosswise of the surface 14 it starts as a curve 14a, which is defined by the radius of the rod, and gradually flattens toward the end. As stated, the extremity may be that of an arc of a circle, as shown in FIG. 2, or straight.

It is preferred that the surface 14, where it terminates at the end 12, be outward from the inner surface of the rod a distance substantially 10% to 50% of the diameter of the rod.

The inner surface of the rod curves outwardly at the endto the zone 12, as best shown at 16 in FIGS. and 6. To this end, the inner curved surface may start in a narrow zone 16a and curve outwardly and laterally as shown at 16b, and finally curving inwardly at the end and merging with the zone 12. As viewed from the side, the outward curvature 16, FIG. 5, may be on a radius approximately the same as the diameter of the rod and preferably not less than the radius of the rod. The ends may be formed by a suitable swaging operation in properly formed dies. Should there be any flash metal on the end, it may then be ground off to provide the zone 12. Preferably the'zone 12 is not a clearly defined zone but is a zone the top and bottom of which merges smoothly with the surfaces 14 and 16.

It will thus be seen that the inner end surface 16 provides a rounded end which cannot scratch or nick the line during application. Furthermore after application the line may move or work longitudinally relative to the rods, without the rods fretting the line or the rods wearing at the ends to a sharp edge.

The curvature of the portion 14 is such that it causes a reduction of the electrostatic field. It is believed that this surface with the surface of the conductor act together to prevent the end zone 12 from being a source of corona.

Having thus described the invention in some embodiments thereof, I am aware that numerous and extensive departures may be made therefrom without departing from the spirit or scope of the invention as defined by the appended claims.

I claim:

1. For use in combination with a high voltage line, a corona reducing armor rod comprising a hard drawn resilient member in the form of an open helix having an inner diameter less than the diameter of the line, the improvement which comprises at least an end of said rod shaped to provide an outer portion starting spaced from the end of the rod, which curves toward the inner diameter of the helix and a surface on the inner side of the rod which curves outwardly toward the outer diameter of the helix, the two described surfaces meeting to form a spatulate end zone which is curved transversely to the axis of the helix.

2. A device as described in claim 1, in combination with the line wherein the ends extend in a circumferential zone spaced from the periphery of the line.

3. A device as described in claim 1, in combination with the line wherein said ends are curved to conform to a circumferential line extending around and spaced from the line.

4. For use in combination with a high voltage line conductor, a preformed helical member of resilient conducting material having an inside diameter slightly less than the conductor and an open pitch such that it may be applied to the conductor without permanent deformation,

said helical member having at least one end formed to cause greater area distribution of the electrical potential, to prevent corona, comprising a portion at the end extending from the inner diameter of the helix away from the conductor for a distance between 10% and 50% of the diametrical cross section taken through said member, the outer surface of said end curving downward toward the helical axis for a distance between and 50% of the diametrical cross section of said member to meet said first curved surfaces, said curved surfaces forming an end which is curved on a radius at least equal to a radius of said member and extending on a geometrical line substantially perpendicular to a diametrical line drawn through said helix.

5. A device as described in claim 4, in combination with the line wherein said high voltage line is provided with a substantially complete sheath formed by a plurality of preformed helical members and said ends are disposed in the plane of a ring surrounding said high voltage line with the inner extremities being curved away from the high voltage line and the outer extremities curving toward said high voltage line, the curvature of the outer extremities being on a radius at least equal to the radiusof the high voltage line and the curvature of the inner extremities being on a radius less than that of the high voltage line.

References Cited by the Examiner UNITED STATES PATENTS 2/52 Peterson 174--136 X 4/63 Ruhlman 174-127 OTHER REFERENCES JOHN F. BURNS, Primary Examiner.

DARRELL L. CLAY, Examiner.

Claims (1)

1. FOR USE IN COMBINATION WITH A HIGH VOLTAGE LINE, A CORONA REDUCING ARMOR ROD COMPRISING A HARD DRAWN RESILIENT MEMBER IN THE FORM OF AN OPEN HELIX HAVING AN INNER DIAMETER LESS THAN THE DIAMETER OF THE LINE, THE IMPROVEMENT WHICH COMPRISES AT LEAST ON END OF SAID ROD SHAPED TO PROVIDE AN OUTER PORTION STARTING SPACED FROM THE END OF THE ROD, WHICH CURVES TOWARD THE INNER DIAMETER OF THE HELIX AND A SURFACE ON THE INNER SIDE OF THE ROD WHICH CURVES OUTWARDLY TOWARD THE OUTER DIAMETER OF THE HELIX, THE TWO DESCRIBED SURFACES MEETING TO FORM A SPATULATE END ZONE WHICH IS CURVED TRANSVERSELY TO THE AXIS OF THE HELIX.

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