Patent Application
20110039434
1. Field of the Invention
This invention relates to the field of power transmission and, more particularly, to connectors for high tension power transmission lines.
2. Background
Connectors play a critical role in the efficiency and reliability of power transmission systems. Aluminum cables used for overhead transmission lines require connectors for splices and dead end assemblies. Currently available connectors are typically tubular aluminum devices that are crimped or swaged onto the cable. In order to achieve a full or nearly full tension fitting, prior art connectors require numerous crimps or swages and are therefore relatively long and heavy. In addition, the installation tools for prior art connectors are large and unwieldy. During the installation of prior art connectors, the length of the fitting and the size of the tooling may result in undesired bending of the connector.
The present invention provides an improved connector with a body having a substantially cylindrical outer surface and a stepped series of substantially cylindrical inner surfaces with progressively smaller inside diameters. The design of the connector allows for improved control of the compression of the cable inside the fitting. A series of swages, progressing successively from a light compression to a heavier compression, ensures that the connector will sustain the required tensile load.
In comparison to prior art connectors, the present invention provides a smaller, lighter full tension connector that can be installed with fewer swages. Installation of the connector is quicker and easier than prior art counterparts. Furthermore, the connector is less prone to bending during installation.
In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail.
A connector 10 in accordance with one embodiment of the present invention is shown in
To install the connector 10 onto a cable, the end of the cable is inserted into the connector body to depth C. The connector is compressed onto the cable using a hydraulic swaging tool. A suitable swaging tool may be, for example, the tool disclosed in U.S. Pat. No. 7,299,674 and commercially available under the CableLok® brand from Designed Metal Connections of Gardena, Calif. The design of connector 10 allows it to be installed on the cable using a single die set.
The first swage area at the end of the connector (i.e., between the end of the connector body where the cable is inserted and depth A) carries the maximum load. This has the minimum compression, thereby minimizing damage to the cable. The second swage area (i.e., between depth A and depth B) holds the load that the first swage area cannot take and has a heavier compression to provide better electrical contact. The third swage area (i.e., between depth B and depth C) carries less load, but provides the best electrical contact. When properly installed, connector 10 can sustain a load of 95% or more of the rated strength of the cable, thereby meeting the requirements for class 1 full tension fittings of the C119.4 ANSI standard.
As will be appreciated, the specific dimensions of connector 10 are dependent upon the dimensions of the cable with which it will be used. The smallest inside diameter, in this case d3, is slightly greater than the nominal outside diameter of the cable. The inside diameter step sizes (i.e., the difference between d1 and d2 and the difference between d2 and d3) may be less than about 0.05 inches. The axial length of each step (i.e., the distance from the end of the connector body to depth A, from depth A to depth B, and from depth B to depth C) is determined primarily by the dimensions of the swaging tool head and may be approximately 1 inch. Connector 10 has been described as having three swaging segments; however, it is to be understood that other embodiments of the invention may have more or fewer segments.
Connector 10 may be configured either as a splice connector with a tubular body receiving a cable at each end or as a full tension dead end having a suitable structural coupling. In one embodiment, connector 10 is fabricated with 6061-T6 aluminum alloy, although other alloys may be used. In this embodiment, the connector body is heat treated (annealed) after machining.
It will be recognized that the above-described invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the disclosure. Thus, it is understood that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.
