US2918520A - Multiple conductor spreader - Google Patents

Description

L. J. STEVENS MULTIPLE CONDUCTOR SPREADER Dec. 22, 1959 2 Sheets-Sheet 1 Filed May 7, 195'? De'c- 1959 L. J. STEVENS 2,918,520

MULTIPLE CQNDUCTOR SPREADER Filed May 7, 195'? 2 Sheets-Sheet 2 United States Patent" 2,918,520 MULTIPLE CONDUCTOR SPREADER Leland J. Stevens, Baltimore, Md., assignor to General Electric Company, a corporation of New York Application May 7, 1957, Serial No. 657,567 1 Claim. (Cl. 174-146) This invention relates to a multiple conductor spreader, and more particularly, to a spreader or strut for high voltage transmission line installations which have multiple conductors per phase of electrical energy.

It is well known to use a single conductor for each phase in electrical transmission line installations. With the advent of higher transmission voltages there has been greater interest in using several conductors for each phase of electrical energy. When multiple conductors are used considerations such as space and economy require that the conductors be positioned rather close to each other. swaying or whipping about of the conductors by high winds may cause them to get tangled together. Therefore, spreaders or struts are necessary.

Spreaders or struts for multiple conductors cannot be too rigid. This is because some limited movement of the conductors is desirable. Also, after flexing to permit limited movement of the conductors the spreaders or struts should recover to theiroriginal condition. Repeated flexing of the Spreaders or struts should not weaken their ability to recover. Additionally, they should be low cost and light weight, have a minimum number of separate parts, and be capable of convenient and rapid installation.

It is an object of this invention to provide a multiple conductor spreader or strut which will have the abovementioned desirable characteristics.

In my invention the spreader or strut is constructed from a material which will have a long life and which wiil not fail because of crystalline fatigue after repeated flexing, bending or twisting and will not lose its ability to recover to its original condition throughout its long life. The spreader or strut is flexible enough to allow the conductors limited movement and rigid enough to keep the conductors properly spaced so'they do not become tangled together. Also, the spreader or strut has a small number of parts and is provided with clamping means whereby it can be conveniently and rapidly installed and the clamping means will not place high unit clamping pressures on the spreaders or conductors. The features of my invention which I believe to be novel are set forth with particularity in the appended claim. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a perspective view of one form of my invention; and

Fig. 2 is an enlarged view of the spreader of Fig. 1 when looking in the direction of arrow 2 of Fig. 1; and

Fig. 3 is a sectional view of the spreader taken along the sectional line 3-3 of Fig. 2; and

Fig. 4 is a perspective view of another form of spreader; and

Fig. 5 is a sectional view taken along the line 5-5 of Fig. 4; and

Fig. 6 is a perspective view of still another form of spreader; and

Fig. 7 is a sectional view taken along line 7-7 of Fig. 6.

Referring now first to Fig. 1, illustrated therein are a pair of generally parallel and spaced electrical conductors 1 which are supported from one end of a crossarm 2 of a not shown line pole, tower structure, or other supporting means. The conductors are shown as being supported from arm 2 by one electrical insulator string 3 although more than one insulator string may be used. The upper end of the string 3 is pivotally connected to arm 2 by means suchas a clevis 4. The conductors are independently pivotally connected to the lower end of string 3. This can be accomplished by pivotally connecting the lower end of string 3 and a pair of saddle type suspension clamps 5 of the conductors to a yoke element 6. The yoke element 6 may have the form of a short and generally isosceles triangular-shaped plate which is pivotally connected to the string 3 at its obtuse corner by means such as a clevis 7 and to the clamps 5 at its acute corners by means such as clevises 8.

Since the clamps 5 are pivoted to yoke element 6 the conductors 1 can move with respect to each other. However, since the distance between adjacent crossarms or conductor supports is quite long the conductors may become tangled together if they are permitted to swing freely throughout their whole length. Therefore, the conductors are spaced at one or more points between adjacent conductor supports by spreaders or struts. In Fig. l the illustrated form of conductor support is of the suspension type. However, the above considerations also apply to tensioned forms of conductor supports, as of the dead end type. Therefore, my invention is not restricted in its usefulness to the particular form of conductor support illustrated in Fig. l. The spreader in Fig. 1 is indicated generally by reference numeral 10.

Referring now also to Figs. 2 and 3, the spreader 10 comprises a ring 11. Ring 11 may be circular. However, I prefer to give ring 11 an elongated or oval shape since I have discovered that this type of shape will not be as rigid as a circular shape.

The ring 11 is constructed from a resilient non-metallic material such as neoprene rubber. Other suitable resiiient non-metallic materials are epoxy resins. These resilient non-metallic materials aremore satisfactory than resilient metals because they are lighter in weight and less apt to fail or lose their resiliency due to crystalline fatigue after repeated flexing, bending, or twisting. Addi= tionally, though they are rigid enough to keep the conductors spaced apart they are flexible enough to allow the conductors limited movement. Also, they can be readily fabricated by methods such as molding. For instance, the ring 11 may be a continuous molded member.

The ring 11 is connected to the conductors 1 by a pair of clamps 12 which are removably clamped to the conductors 1 as well as the ring 11 with low unit clamping pressure so as not to bite into the conductors or ring. The clamps 12 may comprise three members 13-15 which are generally elongated and curved in the transverse direction so as to avoid concentrated and high unit clamping pressure on the ring and conductors. The members 13 and 15 have generally concave and lengthwise extending inner grooves for seating the ring and conductors respectively. The members 14 have generally concave and lengthwise extending inner and outer grooves for seating the rings and conductors respectively.

These three members 13-15 are firmly clamped about the ring and conductors by means such as U-bolts 16. A pair of generally transversely extending grooves 17 can be formed in the back of members 15 to seat the bridge portions of bolts 16. A pair of apertured length wise extending ears 18 can be formed on members 13 to receive the threaded ends of bolts 16 and the clamp can be tightened by means such as nuts and lock washers. The members 14 can be held from sliding out of place by forming a pair of lengthwise extending cars 19 thereon which will fit between the pair of bolts 16 of each clamp 12.

If so desired the ring 11 can be stiffened and strengthened by molding the resilient non-metallic material about a reinforcing member. The reinforcing member can take the form of a central flexible stranded metallic cable 20.

In the Fig. 4 form of my invention the spreader is in the form of an elongated resilient strut. The strut comprises two'superposed non-metallic strips 21 which can buckle with respect to each other and can be constructed from similar material as ring 11. At their opposite ends the strips 21 have generally transverse inner grooves formed therein. Each opposed pair of grooves will define a generally cylindrical space for conductors 1. The opposite ends of the strips 21 may be clamped to the conductors 1 by means such as wide and generally C-shaped metallic clips 22 which straddle the ends of strips 21. The clips 22 may be tightened by means such as nuts and bolts and lock washers.

The Fig. 6 form of the invention is similar to the strut of Fig. 4 except that a single non-metallic elongated member 25 is used to space the conductors 1. Opposite ends of the member 25 are enlarged slightly and transversely bored and slitted. The opposite ends of member 25 may be clamped to conductors 1 by means such as wide and generally C-shaped clips 26 and bolts, nuts and lock washers. Preferably the member 25 is cylindrical since snow and ice will be less apt to accumulate on curved surfaces than on flat surfaces as 21 of Fig. 4.

In the Figs. and 7 forms of the invention since the clips 22 and 26 are electrically insulated from the conductors 1 a static discharge may occur between the conductors 1 and the clips 22 and 26 and their nuts and bolts. This occurrence can be avoided by electrically connecting the conductors and the clips. The electrical connection can be performed in several ways. Electrically conductive wire or ribbon can be used between the conductors and clips or the opposite ends of the struts could be covered with an electrically conductive coating. Also, the struts could be made electrically conductive by incorporating a suitable electrically conductive chemical composition into the resilient non-metallic material. The last mentioned expedient is well known as in the electrically conductive rubber gasket art. However, by way of illustration, in the Fig. 5 form of the invention I employ thin metallic ribbon clips 23 or the like on opposite ends of the strips 21 to place the conductors 1 and clips 22 at the same electrical potential, and in Fig. 7 I employ a conducting surface coating 27 on the opposite ends of the member 25.

In all forms of the invention the outer parts'of the clamping means are rounded off whereas the sharp parts of the clamping means which may be conducive to corona are positioned on the inside between the parallel conductors. For instance, the bridge portions of the bolts 16 and the clips 22 and 26 are rounded off, and the parts having sharp edges such as the other ends of the clips 22 and 26 as well as their nuts and bolts and the threaded ends of the bolts 16 and their bolts are located on the inside between the parallel conductors so they can be shielded by the parallel conductors.

While there have been shown and described particular embodiments of the invention it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention, and therefore, it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

In a high voltage electrical transmission line installation which comprises a pair of spaced and generally parallel conductors per phase of electrical energy, means for maintaining said conductors in spaced relationship while simultaneously affording them a limited degree of movement with respect to each other, said means comprising a single elongated resilient neoprene rubber member which extends between said conductors and at its opposite ends straddles said conductors, said opposite ends having generally elongated slotted bores formed therein for receiving said conductors, and means for clamping said opposite ends to said conductors with low unit clamping pressure, said clamping means comprising generally 6- shaped metallic clips which straddle said opposite ends, the bridge portions of said clips being curved and located outside said conductors and the other portions of said clips being located between said conductors, and electrically conductive means for electrically connecting said conductors to said clips.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Germany, Pfisterer, Serial No. P.10108 VIIId/21c, March 8, 1956.

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