DC motor cooling considerations

DC motors have been the workhorse of variable speed drives in the paper industry for many years. DC motors in paper mills are usually separately ventilated from a large common air supply. The quantity and quality of the cooling air can have a major impact on the DC motors' performance, operation, maintenance and life between overhauls. Information presented here describes cooling air considerations, corrosive air and its effect on motor performance and life, and ways to assess and reduce this issue.