Abstract: A torch having a first non-constricting arc electrode disposed within the longitudinal bore of a second non-constricting arc electrode with the ac attachment end of the second arc electrode being annular in cross-section and extending a predetermined distance from the current transfer means for the first arc electrode. An arc is established from the arc attachment end of each arc electrode from at least one source of power. Both arcs are shielded in common with a single common shielding medium.

Abstract: In a direct current machine having plural brushes arranged for sliding engagement over the surface of the commutator assembly along separate paths; wherein the commutator assembly comprises a multiple number of commutator bars with each bar having a current transfer surface divided into conducting and nonconducting sections, each section being located in one of the separate paths, and with the sections of adjacent commutator bars so arranged to provide a checkerboard pattern of conducting and nonconducting sections over the commutator assembly surface. The brushes are interconnected to the machine load through a predetermined circuit network which controls the short circuit current.