Reliability and Life of DC Motors and the Ree System

Remarkable improvements have been made during the last years on materials, surface treatment and lubrication of sliding electrical contacts. This resulted in a significant increase in the life of precious metal brushes and commutators used in DC micromotors. Although not negligible, the electro-erosion caused by arcing during commutation is greatly reduced in ironless DC motors because of the low inductivity of their windings.  Remember that for the brushes the number of commutations per revolution is equal to the number of segments of the commutator (for instance 9), whereas a commutator segment is switched twice per revolution, at the positive and negative brush. In order to reduce wear caused by electro-erosion, Portescap has developed the REE® System (Reduction of the Electro-Erosion) which allows for reducing commutation wear by a theoretical 75%. The system acts mainly by limiting the inductance of the coil sections during commutation, accompanied by measures concerning the brush gear.

The struggle against waste and competition has forced designers to increase the reliability and the life of their equipment. This, of course, can only be made possible with correspondingly high-quality components and careful selection of their suppliers. At this point the REE System, applied to motors already known for their reliability and long life, allows for interesting solutions to the difficult problem of selecting a DC motor offering the best price performance/life ratio.

To learn more about this important topic, please view the complete white paper or contact an engineer.