الفهرس | Only 14 pages are availabe for public view |
Abstract motors the main objectives electrical adequate speed adjustment with control,; is to provide respectfto the mechanical motor tP. depends on the amount and cost of equipment load. The selection oproper t-equiredto achieve the speed control on the motorSince the speeds of direct current motors are easily controlled, they have dominated the adjustable speed drive I ~ield in industry. The drive circuits vary ~rom miniature drives with current of only few milli-amperes to heavy industry and traction with thousand amperes such as steel- mill drives, aluminium mill drives, textile drives, plastic 1 sheet drives, paper drives, and traction drives. Pr~viously the speed of DC-Motors had been increased by connecting resistance in series with the shunt field, while the speed reduction below rated speed was obtained by connected rheostat in series with the motor armature. |