Environment and brushes for high-current rotating electrical machinery

A high-current electrical machine, comprising a stationary and a moving member and at least one fibrous current collector brush disposed between the members and in frictional contact with one member, the improvement comprising a current collector brush comprising a plurality of flexurally independent, electrically conducting, solid metal fibers where the mechanical fiber load of the brush at the area of frictional contact is between 1.times.10.sup.-6 lb./fiber and 1.times.10.sup.-2 lb./fiber, and shielding said area of frictional brush contact from air while providing to said area a non-oxidizing gaseous medium containing an amount of water vapor effective to form a lubricating film between the brush and the frictionally contacting member at their interface, to allow current transfer to the brush and yet provide a lubricating effect and minimize wear at the area of brush friction.