Abstract
The burnt trace on the anode brush by commutation arc is measured and compared with the arcing energy, in the region of little brush wear. We obtain the following results;
(1) volume of the brush burnt trace depends on the arcing energy approximately exponential in the region of little friction wear,
(2) burnt trace progress mainly toward the circumferential direction and very small in the radial direction,
(3) the variation of the burnt trace volume is influenced by the remained contact area,
(4) the quantity of the burnt trace volume is effected by the brush grades, and is inverse relation of the sparking easiness.
