Abstract :
THE mechanical and electrical advantages stemming from the use of linear conductors of structural shape∗ are so marked that, at present, most busses for heavy current duty are constructed of such conductors. Thus, standard designs of single and polyphase busses utilize strap conductors of full rectangular cross section, tubular conductors of hollow rectangular cross section, or ventilated conductors of open hollow rectangular cross section — these last built up of two slightly separated channels or four slightly separated angles placed flange to flange, or of multiples of four thin strap conductors. Again, limited construction of a somewhat more specialized type of bus has resulted from Arnold´s1 discovery that minimum eddy-current losses are attained in a single-phase circuit if, of the conductors commercially available, the bus is constructed of two properly chosen channels placed back to back. Finally, the use, in shielded busses, of conductors of T and I cross section is not unknown.
