CA1066375A - Spacer-damper for electrical transmission cable - Google Patents

Abstract

SPACER-DAMPER

ABSTRACT OF THE DISCLOSURE

There is disclosed a spacer-damper for electrical transmission cable or the like. A rigid spacer composed of mating half-sections having at its extremities hollow spherical sockets for receiving the spherical end portions of individual cable connector structures. The opposite ends of the connectors are fashioned for effecting a gripping connection with a cable. A resilient damping material is interposed between the spherical connector end portions and their associ-ated receiving sockets and the damping material is secured to both the ball and the socket so that on pivoting of the connector arm attendant cable vibration or oscillation the damping material is placed in shear to effect a damping action.

Description

Introduction The present invention relates generally to the : suspension of electrical transmission lines or the like and, more specifically, is directed to a new and improved de~ice _ for maintaining a predetermined minimum spacing between subconductors on a bundled conductor transmission line while concomitant]y suppressing undesired vibration and~or oscillations of the lines.
Background of th~e Invention There are two primary types of vibration which cause damage to bundled conductor transmission lines, namely, aeolian vibration and subconductor oscillations. Aeolian vibration occurs in the ~ertical planej i.e., perpendicular to the ground, and at high frequencies and low amplitudes. To suppress this type of vibration it is known to impose a resilient connection between the conductor clamping means and the body of the spacer, allowing limited flexing in the vertical plane. Subconductor oscillations, on the other hand, occur in a horizontal plane at low fre~uencies and at relatively large amplitudes. Suppression of this type of vibration requires a resilient connection between the conductor clamp and body of the spacer which allows limited flexing in the horizontal plane. Since both types of vibration can exist at the same time, simultaneous flexing in both planes is necessary in order to effectively suppress such vibrations. Prior art devices such as illustrated in the following U.S. Patents- -No. 3,479,441 issued November 18, 1969 to Edwin Barclay Moore, No. 3,083,258 issued March 23, 1963 to Aubrey Thomas Edwards, Jack A. Foster and Edward F. Bradshaw, No. 3,567,841 issued March 2, 1971 to Masashi Kobayshi, No. 3,263,021 issued July 26, 1966 to Alan Caunt, No. 3,465,089 issued September 2, ;~
1969 to Ralph P. Torr, No. 3~609,209 issued September 28, 1971

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to Herbert James Houston, Robert Gordon Baird, Kenneth Dale solt and Adolf Gretzinger, and No. 2,915,580 issued December 1, 1959 to John Edward Gill and Edward William Fletcher have not provided wholly satisfactory operation. Other spacer-damper devices _ illus~rative of the state of tne art are disclosed, for example, in United States Patent No. 3,260,789 issued ~uly 12, 1966 to Aubrey T. Edwards, No~ 3~474rl84 issued October 21, 1969 to Noble W. Crosby, Robert C. Walker and Gordon J. Clarke, No. 3~454~705 issued July 8, 1969 Noble W. Crosby, Gordon J.
10 Clarke and Robert C. Walker, No. 3,443,019 issued May 6, 1969 to Robert C. Walker and Gordon J. Clarke and No. 3,617,609 issued November 2, 1971 to Paul D. Tuttle.
Sum ary of the Invention It is the primary objective of the present invention to provide a new and improved spacer-damper appliance for suspended cables which appliance effectively damps both aeolian vibration and subconductor oscillations.
ThP structure of the present invention provides a predetermined cushioning and damping :influence on the motion components o~ bundled conductor transrnission lines thereby to alleviate or preclude vibration transfer between the sub-conductors, torsional oscillations, excessive swaying of the lines and sharp impact between the subconductors such as are apt to cause damage to various line components such as structures, insulators and/or the conductors themselves.
The spacer-damper of the invention includes a ball and socket connection between a cable connector arm and a rigid spacer portion of the structure. A resilient damping material such as neoprene or other elastomeric or plastic material is interposed between the ball and the receiving socket and is fixedly secured to both cvmponents. The damping material is placed in shear as a result of relative pivotal movement between :
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IL~ li63~5 the ball and socket components. Use ~f an elastomer in shear as opposed to the development of compression or tensi.on on the elastomer has been found highly effective in suppressing aeolian vibration and subconductor oscillations.
In accordance with one broad aspect, the invention relates to a device for maintaining a predetermined minimum spacing between electrical transmission cables or the like and for damping vibratory oscillatory motion of such cables, comprising: cable connector means comprising a plurality of similar connector structures each having a longitudinal axis, a firs~ end portion for effecting a gripping connection with.
a cable and a second end portion of a generally spherical ball-like contour; rigid spacer means including a plurality of ~ hollow sockets of a generally spherical contour, each said ;~ socket receiving respective ones of said ball-like end portions : of said cable connector means; said cable connector means and said spacer means disposed in a common plane; resilient damping means interposed between said ball-like second end portions of each of said connector structures and the associated receiving sockets of said spacer means; and means securing said damping means against movement relative to both said ball-like end portions of said connector means and their :
associated receiving socket for placing said damping means in ., .
shear upon relative pivotal movement of said ball-lik~ end : -portions and their associated receiving sockets, said securing means including circumferential ribs on said damping means, said ribs mating with complementary circumferential recesses in the respective receiving sockets and in the ball-like end portions, and each said rib and said recess being generally perpendicular to the longitudinal axis of their associated -~ connector structure and to said common plane.
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Brief Description of the Drawings The novel features of the present invention are set :~ forth with particularity in the appended claims. The invention j:
together with further objects and advantages thereof may best _ be understood, however, by reference to -the following description taken in conjunction with the accompanying drawings in the several figures of which like reference numerals identify like elements and in which:
FIGURE 1 is a perspective view of a spacer-damper 10. device of the invention as applied between a trio of electrical transmission ca~les; -FIGURE 2 is an enlarged plan view of the major components of the device of FIGURE l; and FIGURE 3 is an elevational view partly in section of . the connector arm component of the device~
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~i6375 DESCRIPTION OF THE PREFERRED EMBODI~ENTS

Referring now to FIGURR 1, there is s~own a spacer assembly 10 according to the present invention and including a rigid triangular spacer means 12 and associated connector means 14, 16 and 18. As will presently be explained in detail, the connector maans 14, 16 and 18 each have one end portion coupled to a vertex of the triangular spacer 12 and respective opposite -~ end portions coupled in gripping relation to corresponding ones of a plurality of suspended lines 20, 22 and 24. The suspended lines 20, 22 and 24 herein illustrated are the so-called bundled conductors used in the transmission of electrical power and, in this regard, it will be understood that the lines are at a like . . ~
electrical potential consistent with ~he pri~ciples of the present invention. ~urthermore, although ~he spacer 12 is of a triangu-- lar configuration, it will be recognized by those skilled in the art that the principles of the invention are applicable to the spacing of any two or more lines and that the spacer may take -~
th~ form of a straight arm, a rectangle and so on.

The cable en~aging end portions of the connector means 14, 1~ and 18 are in the form of identical U-shaped members of a dimension for accommodating an individual cable between the ;~
legs of the U. The cables are secured to the U-shaped end portions of the respective connectors by means of respective sets of conventional helically preformed elements 26, 28 and 30 -intertwined about the cables and U-shaped end portions of the connectors. Each set of helical rods is composed of at lsast ; one and preferably a plurality of individual helical elements.

The illustrated structure of the U-shaped end portions , of the connectors 14, 16 and 18, as well as the preformed -helical rods 26, 28 and 30 for maintaining the connectors in secure engagement with the respective cables are substantially

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identical to that disclosed in U.S. Patent No. 3,463,870, assigned to the same assignee as the presen~ invention. However, it will be understood that other cable gripping arrangements may be used in place of that described consistent with the teachings of the present invention.
In accordance with the present invention, aeolian vibrat-ions and subconductor oscillations are suppressed by means of a particular structural interconnection between the connector means 14, 1~ and 18 and the triangular spacer 12. The struct-ural features of the invention may be appreciated by referenceto FIG~RE 2 wherein the spacer 12 is composed of a pair of mat-ing and identical half-sections 12a and 12b. Each of the three sides of the exemplary half-section 12a is composed of aluminum or other generally rigid material. The three vertices are integrally connected to the legs and are formed wi~h identical hemispherical recesses exemplified by the recess 32. In the present embodiment, the sidewalls of the hemisphere 32 and the sidewalls of its counterpar~s are provided with a groove or depression lying on a diameter of the hemisphere. A horseshoe-shaped flange 36 i5 formed about t4e periphery of each hemis-pherical recess and is provided ~ith a pair of spaced bolt receiving apertures for facilitating securance to the mating flange 12b. As is apparent Erom the drawing, each of the hemis-pherical recesses of the spacer sections 12a and 12b are identi-cal and upon assembly of the two sections, three generally ~ i spherical receiving sockets are formed by the mating hemispher-ical sections. The half-sectlons of the spacer are retained in assembled relation by six bolts extending through the pairs of bolt apertures formed in the flanges about each hemispheric-' 30 al recess.
The generally spherical or ball-lîke second end portions of each of the connector means 14, 16 and 18 is disposed in a ' ' . ~ ' : ~ . ' ' . ., " ;. ,: .... .

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respective one of the spherical receiving sockets. In FIGURE 2~
the ball-like end portions of the connectors 16 and 18 are shown seated in respective hemispherical recesses of the spacer 12a, while the connector 14 is shown removed Erom its associated socket. Assembly of the device is completed ~y installing the connector 14 in its associated hemispherical recess, placing the mating spacer section 12b over the described subassembly and ~ bolting the two sections together.
; In accordance with the present invention, a mechanical -~; 10 interconnection is effected between the ball-like second end -portions of each of the connector structures 14, 16 and 18 and - the associated receiving sockets of the spacer in a manner so as to develop shear forces across a resilient damping means inter- -posed between the socket and connector structures. It has been Eound that provision of a joint wherein the resilient material is placed in shear affords an improved damping of aeolian vibra-tion and subconductor oscillations as compared to prior art con-structions wherein the resilient damping material is plared in tension or compression. In the present embodiment and as depic-ted in connection with the exemplary connector structure 14, a layer of resilient damping material 38 is disposed over ~he ~, -outer surface of the ball-like second end portion of the connec-tor 14. A circumferential rlb 38a formed integrally with the layer 38 is of a dimension complementary to the groove 34 in the socket recess 32. The rib 38a in con~unction with groove 34 provide an interlock between the resilient layer 38 and the receiving socket so that pivotal movement of each ball within its associated socket results in a shear force being applied across the layer of resilient material~
~, 30 A better understanding of the &tructure of the exem-plary connector 14 may be had by reference to FIGURE 3. A&

there shown, the ball-like second end portion includes a rigid ~ 7 ~

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generally spherical core 40 composed of metal or the like and integrally connected to an arm member 42. The sphere 40 at its point of connection with the arm 42 is slightly truncated in a plane transverse to the axis of the arm 42. The resilient dam-ping material 38 which may be any one of a variety oE convent-ional resilient damping materials, such as Neoprene or other elastomeric or plastic material, is applied as a generally uni-form layer over t~e exterior surface of the ball 40, excepting ` for the circumferential ribs 38a and 38b. The ribs 38a and 38b preferably are located along a diameter of the ball 40 and in a plane perpendicular to the axis of the arm 42. As previously mentioned, the rib 38a is of a dimension complementary to that of the receiving socket groove, and must furthermore be of a size and rigidity to assure a secure mechanical interconnection with the socket under normal operating conditions. To this ` same end, the spherical receiving socket is preferably dimensio~
ed relative to its associated ball so as to apply a firm press-ure to the ball. As an alternative or supplement to the mechan-lcal interconnection ~ormed by the rib 38a, the damping means 38 may be adhesively assured to the receiving socket during assembly. The truncated portion of the bal~ and the associa~ed lip of each receiving socket cooperate to captivate the connec-~or structure and prevent excesslve plvotal movement of the connector relative to the receiving socket.
~ The thickness and rigidity of the elastomeric material - as well as i~s precise composition are dependent upon the contem-plated operating environment and are empirically determined.
The exemplary connector 14 also includes a first end ' portion for effecting a mechanical interconnection with a cable.
' 30 The structure of the first end portion as herein disclosed is identlcal to that disclosed in U.S. Patent No. 3,463,870, assigned to the same asslgnee as the present inven~ion.

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Specifically, the first end portion comprises a rigid generally U-shaped cable receiving portion 44 integral.ly connected to a bolt 46 that is threadably received in a sleeve of the spacer arm 42. The axis of the bolt 46 is transverse to the open mouth of the U-shaped member 44. The threaded interconnection between the first and second end portions of the connector 14 :: permits a manual adjustment of the effective length of the connector. ~lthough not illustrated, a locking nut may be pro-vided for precluding relative rotational movement between the 10 respective end portions of the connector. Alternatively, the sleeve portion of spacer arm 42 and threaded end of cable recei-ving portion 44 can be made without threads and the assembly made by crimping or compressing the said sleeve portion after adjustment of ~he components to a desired r~lative axial posit-ion. The rigid U-shaped member 44 is embedded in a rubber-like cushion material 48. The molded cushion 48, in addition to absorbing impact forces from the cable and damping excessive motion thereof, also prevents abrasion or fatigue damage to the . spacer end portion 44, the cable and the surrounding helical elementsO
While particular embodiments of the present invention have been shown and described, it is apparent that various changes and modifications may be made, and it is therefore intended in the following claims to cover all such modifications and changes as may fall within the true spirit and scope of this ~nvent~on.

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A device for maintaining a predetermined minimum spacing between electrical transmission cables or the like and for damping vibratory oscillatory motion of such cables, comprising: cable connector means comprising a plurality of similar connector structures each having a longitudinal axis, a first end portion for effecting a gripping connection with a cable and a second end portion of a generally spherical, ball-like contour; rigid spacer means including a plurality of hollow sockets of a generally spherical contour, each said socket receiving respective ones of said ball-like end portions of said cable connector means; said cable connector means and said spacer means disposed in a common plane; resilient damping means interposed between said ball-like second end portions of each of said connector structures and the associated receiving sockets of said spacer means; and means securing said damping means against movement relative to both said ball-like end portions of said connector means and their associated receiving sockets for placing said damping means in shear upon relative pivotal movement of said ball-like end portions and their associated receiving sockets, said securing means including circumferential ribs on said damping means, said ribs mating with complementary circumferential recesses in the respective receiving sockets and in the ball-like end portions, and each said rib and said recess being generally perpendicular to the longitudinal axis of their associated connector structure and to said common plane.

2. The device of claim 1 in which said securing means further includes an adhesive affixation of said damping means to both said ball-like end portions of said connector means and to said receiving sockets.

3. The device of claim 2 in which said first and second end portions of said plurality of connector structures are displaceable relative to one another for adjusting the effective length of said connector structures.

4. The device of claim 3 in which said spacer means comprises a pair of symmetrical mating half-sections secured to one another by bolts.

5. The device of claim 1 in which said circumferential ribs lie on diameters of their associated ball-like end portions.

6. The device of claim 5 in which said ball-like end portions comprise truncated spheres and in which said spheres are truncated in respective planes perpendicular to said longitudinal axes of said connector means.

7. The device of claim 6 in which said first end portion of said connector means each comprises a U-shaped member for receiving one of said cables between the legs of said U.