Mechanical and electrical contact properties of wedge-connectors

Abstract

Abstruct-The paper describes the mechanical and electrical contact properties of a typical fired wedge-connector. The measured forces and displacements in the connector components are compared with the predictions of a finite element analysis (FEA) of a wedge-connector interfaced with solid aluminum conductors. The distribution of mechanical stresses resulting from typical applied mechanical loads are evaluated using a nonlinear FEA code. The nonlinear input data for the FEA calculations were obtained from mechanical testing of metal specimens obtained from connectors used in the investigation. Measurements of contact resistance of the electrical interfaces are also reported. The wipe-off of surface oxide films from the electrical interfaces during connector installation is described.

Environmental degradation of utility power connectors in a harsh environment

“…The effects of corrosion were the most rapid in compression-type connectors and were resisted most effectively in fired wedge-connectors. As indicated in previous investigations [6], the relatively stable performance of fired wedge-connectors stems mainly from the "spring-action" of the connector C-member that resists loss of mechanical contact load, from the uniformity of the stress distribution over the contact interfaces and from the large area of metal-to-metal contact [6]. We conjecture that the generation of a large area of electrical contact, as well as maintenance of a large contact load in the fired wedge-connectors, played a key role in maintaining their electrical integrity for a relatively long time at the Dayton Beach test site.…”

“…Fired wedge-connectors consist of a metal wedge located between two conductors situated at opposite ends of a C-shaped metal component. An electrical connection is formed by inserting the wedge between the two conductors with sufficient force to cause plastic deformation of the C-member [6]. Fired wedge-connectors are installed using a tool actuated by a powder cartridge [6].…”

“…Similarly, the bolted connectors were tightened to the torque recommended by the manufacturer using a calibrated torque wrench. The fired wedge-connectors were installed using the recommended tool and practice [6]. In addition, the surfaces of all conductors in the vicinity of the connection points were wire brushed prior to installation.…”

“…Absence of this capability precludes a capacity for maintaining an acceptable mechanical load with the conductors during service. It is noteworthy that fired wedge-connectors are designed to maintain a steady mechanical contact load through the spring action of the C-member [6]. Another potential connector degradation mechanism stems from the formation of corrosion products.…”

Laboratory performance tests on aluminum splices for power conductors

“…These data are consistent with Bond et al's [5] observations of increased mechanical fracturing of aluminum oxide layers with increasing shear deformation in a frictional interface. Shearing of aluminum-aluminum interfaces is also known to be effective in dispersing aluminum oxide surface films and leads to low electrical contact resistance and highly reliable performance of fired-wedge aluminum connectors [8].…”