Patent Application
20150072574
1. Field of the Invention
This invention relates to the field of connectors for electrical conductors, and, more particularly to swaged connectors for use in a grounding grid.
2. Background
Substations in electrical power distribution systems require a properly designed and installed grounding system to insure reliable performance. Grounding is typically accomplished with a grid of electrical conductors buried in the soil. The substation equipment is connected to the grounding grid by means of cables, rods or bars that are securely connected to the grid.
Connections within and to the grid are typically made using special purpose connectors that are crimped to a grid conductor. The crimping process used to secure a connector concentrates the compressive force at one or a few locations around the circumference of the conductor. This localized concentration of force can result in a poor electrical connection. Swaging is a process that distributes compressive force evenly around the circumference of a cylindrical body. Therefore, a properly swaged connector will generally provide a superior connection in comparison to a crimped connector.
The present invention provides a family of swaged connectors with particular application for joining segments of copper cable that make up a subterranean grounding grid in an electrical utility substation. Removable inserts or “lids” allow the connectors to join onto existing continuous cables prior to installation.
The connectors comprise a body member with at least one swage region having a trough for receiving an electrical conductor, the swage region having an opening extending the length of the trough to allow insertion, in a radial direction, of the electrical conductor into the trough. An insert is configured for mating engagement with the opening in the swage region, such that, when the insert is mated with the body member, an electrical conductor disposed within the trough is radially entrapped in the connector. The connector body and insert have a cylindrical outer surface in the swage region to facilitate swaging the connector to secure it to the electrical conductor. The connector may be configured as a lap splice, tee or elbow.
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.
Inserts 14 are configured with a complementary cylindrical inner surface 18 such that the assembled connector has a complete cylindrical inner surface surrounding the cable in swage regions 24. Inserts 14 have flanges 20 that are received in corresponding slots 22 in body member 12. These flanges and slots define keying surfaces that assist axial insertion of the inserts into the body member and prevent the inserts from being removed radially. The flanges and slots may also be configured with an axial taper toward the center of the body member to prevent the inserts from sliding all the way through the slots and to temporarily wedge the inserts in the slots during installation prior to swaging.
Connector 10 is attached to a cable by first removing the inserts 14 and then placing the cable into trough 16. Inserts 14 are then inserted axially into slots 22. Swage regions 24 of the connector are then inserted into a suitable swage tool and uniformly radially compressed to retain the cable. In one specific example, the swage regions of the connector are 1.00″ wide and have an outside diameter of 1.25″. The swaging operation is preferably performed using the 360° Radial Swage Tool manufactured by DMC Power, Inc. of Gardena, Calif.
The center section 26 of the body member between the two swage regions 24 does not fully encircle the cable for the purpose of reducing the volume of material in the connector. The resulting shorter lengths of the inserts 14 increase the strength of the connector by minimizing the overturning moment created under a tensile load between the 90° portions of the connector.
Bottom tap 28 does not require an insert since the cable, rod or rebar can be inserted axially. The outside diameter of the bottom tap is sized for the swaging tool and will generally have the same outside diameter as swaging regions 24. A hole 30 is drilled to the center of the connector. This hole serves to verify proper insertion depth during installation and allows moisture to escape after installation.
Unlike the previously described embodiments, connector 50 does not have separate swage regions for the connected conductors. Instead, the entire connector body, with inserts 14, is inserted into a suitable swage tool and uniformly radially compressed to retain both of the conductors. In one specific example, the outside diameter of connector 50 is 2.00″.
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.
