The subject innovation is generally directed to an apparatus (and corresponding method for installing same) that maintains a desired spacing of while suppressing motion and other undesirable vibrations and/or oscillations in aerial cables. More particularly, the subject innovation discloses a spacer and spacer damper that can maintain a desired spacing between conductor bundles while employing helically-wound formed-wire to increase strength while enhancing heat dissipation in the underlying conductor(s).
In the utility industry, transmission lines are used to direct electrical energy from one location to another. These lines are used to transmit the energy over short or long distances as necessary or desired. Generally, the utility industry characterizes these lines into classes, such as high voltage lines less than 300 kilovolts (kV), extra high voltage (EHV) lines for voltages between 300 kV and 500 kV, and ultra high voltage (UHV) lines for voltages in excess of 500 kV.
Most often, EHV and UHV lines are employed to transfer power from a generating point to a distribution point. For example, these lines are used to transfer power from a generator step-up transformer to a substation(s) where the power will then be distributed to the distribution or load point. In practice, the transmission distance of energy upon EHV or UHV lines is often in excess of hundreds of miles. While uninterrupted delivery of energy is a primary objective, designers also consider economies of delivery when engineering transmission grids.
To economically design EHV and UHV transmission line systems, engineers often bundle the lines. While a bundled conductor increases efficiencies in design, there are a number of design challenges that arise when two or more conductors are tied together. As such, spacers and/or spacer-dampers are most often used to ensure sufficient separation of the conductors. In practice, spacers are used to ensure sufficient distance between conductors while spacer dampers additionally dampen any vibration in the lines while maintaining a suitable distance between the conductors or lines. By way of example, spacers and/or spacer dampers are most often employed at specified intervals along the span of a transmission line. In a specific example, a single transmission line that spans 2000 feet may have 8 or even 10 spacers evenly distributed along the span of the line. However, because transmission lines are most often employed in 3 phase configurations, there could be 24 to 30 spacers within this 2000 feet span which assist in maintaining required spacing arrangements in triangular, box or ring configurations.
As a result of experimental work done on some of the early EHV lines, the normal distance between conductors should not exceed a predetermined distance (e.g., 18 inches). However, in some geographical areas which are exposed to constant high winds and heavy ice accumulation, experience suggests that the spacing should be shortened or lengthened in order to further stabilize the conductor bundle.
Results of laboratory and field experiments have indicated that one of the most effective methods to reduce sub-conductor oscillation and to increase bundle stability is by reducing subspan lengths. This reduction in subspan length can be accomplished by placing spacers in a non-symmetrical pattern. Asymmetric spacing detunes the entire spacer-conductor system and thereby reduces the incidence of sympathetic vibration between subspans. However, specific recommendations for spacer design and spacer placement should be predicated on an evaluation of the electrical characteristics, the line design parameters, and the environmental conditions.
The following presents a simplified summary of the innovation in order to provide a basic understanding of some aspects of the innovation. This summary is not an extensive overview of the innovation. It is not intended to identify key/critical elements of the innovation or to delineate the scope of the innovation. Its sole purpose is to present some concepts of the innovation in a simplified form as a prelude to the more detailed description that is presented later.
The innovation disclosed and claimed herein, in one aspect thereof, comprises a semi-rigid spacer damper that provides for uniform spacing of horizontally bundled sub-conductors while efficiently dissipating heat from each of the sub-conductors. In particular embodiments, formed-wire outer rods (e.g., helically-formed or spiral-shaped rods) are employed to dissipate heat as well as to increase integrity of the conductors. In operation, the spacer or spacer damper of the subject innovation can maintain consistent electrical characteristics and minimize environmental (e.g., wind) induced motions such as sub-conductor oscillation and aeolian vibration so to minimize or eliminate conductor damage or fatigue. Still further, the subject spacer or spacer damper can prohibit the sub-conductors from entangling due to situations such as galloping, ice unloading, fault current, etc.
The spacer or spacer damper of the subject innovation can be employed in most any transmission line applications. For example, the spacer and spacer damper mechanisms can be employed in high temperature conductor applications as well as applications having substantial environmental effects. Within these applications, various arrangements can be employed in accordance with a particular application. In embodiments, ‘Twin, ‘Tri’, ‘Quad’ or ‘Hex’ arrangements can be employed in accordance with a specified number of conductors.
To the accomplishment of the foregoing and related ends, certain illustrative aspects of the innovation are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the innovation can be employed and the subject innovation is intended to include all such aspects and their equivalents. Other advantages and novel features of the innovation will become apparent from the following detailed description of the innovation when considered in conjunction with the drawings.
The innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the subject innovation. It may be evident, however, that the innovation can be practiced without these specific details.
As described supra, the subject spacer or spacer damper mechanisms of the subject innovation can provide uniform spacing of horizontally bundled sub-conductors to establish consistent electrical characteristics while minimizing environmental effects, overheating and/or damage to the sub-conductors. For example, it will be appreciated that damage can occur as a result of wind induced motions such as sub-conductor oscillation and aeolian vibration. Similarly, excessive heat can cause damage to the conductors. As such, the subject mechanisms minimize these damaging effects as well as keep the sub-conductors from entangling due to galloping, ice unloading fault currents, etc.
As described herein, even though a high temperature elastomer could most often be used for the cushions within the apparatus, other acceptable materials that have been identified can limit the conductor operating temperature to 250° C. (or lower). Additionally, it will be understood that many of the high temperature conductor designs can be operated as high as 250° C. The addition of the helically-wound outer rods increases the conductivity in the area of the spacer and increase the radiating surface. Both the increased conductivity and increased radiating surface will reduce the temperature of the elastomer insert thereby allowing the conductor to operate at a higher temperature, such as 250° C. (or higher).
The addition of the outer rods also reduces the dynamic bending stresses on the conductors, which is necessary for high temperature conductors which have composite core materials that are sensitive to bending (e.g., ACCR (aluminum conductor composite reinforced) and ACCC (aluminum conductor composite core) conductors). These increased heat dissipation and strength (e.g., integrity) characteristics of the spherically-wound outer rods will be better understood upon a review of the figures that follow.
Although the spacer and spacer dampers shown in
Referring now to the figures,
As illustrated in
As shown in
In one aspect, a clamp arm can be secured (fixedly or adjustably) between ‘female’ and ‘male’ housings 1 and 4 so as to provide adequate pivotal movement to achieve desired spacing between conductors or lines. In doing so, a damping element(s) 2 and conductive insert(s) 3 can be used to secure and maintain the clamp arm into position. By way of example, the damping element 2 can have a four-pronged, cross or star shape (among other suitable shapes) which mates with the clamp arm in order to hold the clamp arm into a desired position. Details of an example clamp arm are described below. While a specific clamp arm is illustrated and discussed, it is to be understood that other suitable arrangements may exist in accordance with alternative aspects of the specification.
The damping element(s) 2 and conductive insert (3) can be constructed of most any suitable elastomer, neoprene, rubber, plastic or the like. For example, most any natural or synthetic compressive (e.g., rubber-type) material (e.g., polymer) can be used so long as the material exhibits properties capable of high temperature cushioning or dampening characteristics. While specific fastening arrangements are shown in
With continued reference to
Referring now to the exploded view of an example clamp arm, as shown in
As illustrated, an elastomer clamp liner 7 can be inserted into a suitable area of the arm 5 and keeper 8 in order to secure a conductor upon application. Although clamp liner 7 is illustrated as two symmetrical halves, it is to be understood and appreciated that other liner configurations can be employed without departing from the spirit and/or scope of the innovation. By way of example, in an alternative example, the clamp liner 7 can be constructed in a single ‘donut,’ or other cylindrical shape having a single separation or slot for installation upon to a conductor. While a cylindrical insert (or clamp liner 7) is shown in the figure, it is to be understood that the insert can be of any suitable shape so as to effect support of the conductor. For example, in another aspect, the insert can have a square or block exterior shape having a round or cylindrical groove within. Here, the cylindrical groove can effect grip upon a conductor while the exterior shape can provide for insert within an appropriate receiving area of a clamp arm. It is to be understood that the thickness and/or rigidity of the elastomeric materials described herein as well as their precise composition can be dependent upon a specific operating environment or desired application. In operation, the clamp liner 7 can be installed over the conductor by separating the single separation, and thereafter, the arm 5 and keeper 8 can be enclosed around the clamp liner 7 to complete installation.
As described above, helical or spiral-wound outer rods can be employed to enhance thermal dissipation and strength characteristics of the conductors and space-damper. While these outer rods are discussed with reference to
Referring now to
Referring now to
It is to be understood that these unique properties of apparatuses 100, 200 and 300 allow the specialty conductors to be used on existing transmission lines. More particularly, use of these specialty conductors on existing transmission lines allows for an increase in the allowable amount of power flow through the line without an increase in the conductor sag (e.g., stretch). This decrease in sag is particularly important as, most often, an increase in conductor sag could violate the clearance to ground (and other objects) spacing and/or distance that the line must maintain. This spacing and clearance distance is usually governmentally regulated and dictated by a regulatory body, e.g., the National Electrical Safety Code or NESC.
Because the composite materials used in many of the high temperature, low sag conductors have limited bending stress capability, these materials must be properly protected by the hardware used on these conductors. As such, the subject spacer and spacer damper (e.g., 100, 200, 300) has been designed in consideration of these potential issues. Thus, the unique configuration as illustrated in the figures can alleviate many (if not all) of the concerns associated therewith.
As described above, spacer and spacer dampers are most often employed with regard to transmission lines which operate at voltages of 230 kV, or above. Today, in the United States, transmission line voltages are as high as 765 kV. As will be understood, at higher voltages, a bundle of conductors is most often used for each phase, rather than a single conductor. This bundling can reduce or minimize the electrical (e.g., corona) and audible (e.g., noise) interference generated by the extremely high voltage on the conductors.
A typical bundle configuration can be described as a ‘Twin’ configuration (
Generally, spacers and spacer dampers are used in the spans between the supporting structures to maintain the shape of the bundle, and in the case of the spacer damper, to also dampen bundle motions caused by the wind and other environmental conditions. In a typical configuration, the spacers and spacer dampers are positioned at intervals within the span. For example, the devices are most often positioned within 150 feet to 200 feet intervals along the span, although spacing can vary as appropriate.
As illustrated in the figures, the subject spacer and spacer damper has elastomer (or other cushioning) elements deployed within in the junctions between the supporting frame and the clamp arms which connect to the sub-conductors. These elastomer elements absorb energy to dampen motions in the bundle created by the wind and other environmental conditions. These features are illustrated in
Concepts for a high temperature capable spacer and spacer dampers are shown in
First, as illustrated and deployed in
A second function, feature or benefit of the spiral-wound outer rods is to reduce the heating to the underlying conductor and/or spacer or spacer damper by creating a secondary path for the flow of electricity or electrical current. This secondary path creates an expanded surface area for the radiation of the heat away from the area. As described above, many high temperature, low sag conductors are designed to operate at temperatures as high as 250° C., which is generally twice as hot as a typical spacer or spacer damper is designed to withstand.
In other words, the highly conductive (e.g., aluminum or other suitable material) rods reduce the overall (e.g., conductor plus rods) electrical resistance in the area in which they cover. In turn, the I2R (current squared times resistance) heating is reduced in that region. The expanded surface area created by the aluminum rods also creates a radiator which inherently contributes to producing a cooling effect.
As described supra, the innovation discloses a spacer and spacer damper that can be used in connection with electrical transmission cables or the like. The described apparatus can be constructed of multiple mating half-sections as shown in the previously described figures. As well, the apparatus can be constructed of a single non-mating rigid frame. As shown, elastomer inserts can be employed within the clamp arm assembly to grip the individual cables to provide adequate dampening support. While elastomer materials are discussed supra, it is to be understood that most any suitable material including, but not limited to, neoprene, plastic, rubber or the like can be employed in alternative aspects.
While the structure of the apparatus described with reference to
The example embodiment relates to appliances for linear bodies and, more particularly, is directed to a new and improved dead-end appliance for use with linear bodies. It finds particular application in conjunction with high temperature linear bodies such as high temperature power transmission and distribution line wires, cables, and the like, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other applications such as, for example, use in the construction arts for buildings, bridges and other structures, in manufacture and anywhere there is a need for connection with substantially linear bodies.
With reference again to
It is to be appreciated that bending stresses that can be caused by vibration activity at the clamp arm can be reduced by the additional support of the helically-wound outer rods. As will be understood, if the conductor is not properly protected from vibration (e.g., aeolian vibration) and other movement, fatigue failures can occur. These features, functions and benefits will be appreciated by those skilled in the art.
Still further, the helically-wound overlay rods can be terminated with a standard cut and de-burred rod ends. In other aspects, a ‘ball end’ treatment can be applied to the rod ends. This ‘ball end’ treatment can effect an assembly that is corona free (or near corona free) to a line to ground voltage. Most often, this ‘ball end’ treatment will be used for applications up to and including 230 kV. For 345 kV and higher, a ‘parrot-bill’ rod end treatment can be used to enhance electrical properties and performance characteristics.
As illustrated in
Here, heat can be dissipated by way of the increased surface area in a direction outwardly from the clamp arm. As will be understood and appreciated, this radiator effect can contribute to enhance apparatus life as well as reliability. By wrapping the conductor as well as the conductor-end of the clamp arm with the helically-wound assembly, strength as well heat dissipative characteristics can be greatly enhanced.
What has been described above includes examples of the innovation. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the subject innovation, but one of ordinary skill in the art may recognize that many further combinations and permutations of the innovation are possible. Accordingly, the innovation is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
This application claims the benefit of U.S. Provisional Patent application Ser. No. 60/884,348 entitled “SPACER AND SPACER DAMPER APPARATUS” and filed Jan. 10, 2007. The entirety of the above-noted application is incorporated by reference herein.
Number | Date | Country | |
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60884348 | Jan 2007 | US |