Large electronic D-C motor drives in industry

THE TREND IN INDUSTRY is toward the wider use of adjustable-speed drives. An endless list of processes and conditions suggest the reasons for this trend. A piece of material — it may be a strip of steel or a web of cloth or paper — may pass in continuous flow from one machine to another with each machine doing some work in the material. There will be different kinds of materials, changes in physical properties, and changes in size during processing, all of which will require adjustable speed if processing is to be uniform and if high quality is to be maintained.