Geared versus gearless adjustable-speed drive systems in the pulp and paper industry

The advantages, disadvantages, and system considerations of DC and AC adjustable-speed drive systems are examined. The steps that must be taken to evaluate the economics of a direct drive are identified. Much of the discussion focuses on motor operation while considering total system operation. AC versus DC systems are not compared-only geared versus gearless are compared for each technology. It is found that gearless DC drives offer many advantages over the common geared systems and are widely applicable in the pulp and paper industry. Gearless AC drives also offer advantages over geared systems, but disadvantages do however exist. Direct-drive AC systems are found to be more limited in their applicability