1. Speed variation

The independence of flux creation and electromagnetic torque production makes the DC machine ideally suited to variable-speed drives. With the development of power electronics and microelectronics, the use of DC machines has expanded to meet the needs of a wide variety of industrial processes (machine tools, conveyors, metallurgy, paper mills, transport, food processing, textiles, pumping, ventilation, handling, etc.). However, the presence of the mechanical commutator leads to sparking at the brushes, which is why standard DC machines should not be used in potentially explosive atmospheres (refineries, plastics processing, petrochemicals, etc.).

Wear phenomena in the brush-collector assembly are accelerated in operating environments charged with agglomerating dust or corrosive vapors (textiles, steelworks, cement works, foundries, mines, etc.). To ensure that the...