Bolted aluminum-to-copper connections

The increased use of aluminum as an electric conductor has raised the problem of suitable connectors, especially when connections have to be made between aluminum and copper. Since aluminum-to-aluminum connections offer no serious problems which have not been satisfactorily solved in one way or another, this investigation has been confined to the electrical performance of aluminum-to-copper connections. The purpose of conducting this rather extensive investigation was to determine the feasibility of making direct connections between aluminum and copper, to determine the most suitable finish (plating) for the copper member of the connection (the aluminum member was always bare), and to determine the effect of using a compound in such connections. Although aluminum has been used for many years for the purpose of conducting electric current (mainly for overhead transmission in the form of ACSR, and to some extent for busbars), only very limited information and experience is available in respect to the electrical performance of bolted (clamped) connections made between aluminum and copper.