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Growing concerns over the availability and cost of energy have prompted engineers to seek methods of conservation through reduction of operating costs of supply and return fans in typical air distribution systems. Traditional methods of attaining variable air volume typically utilize thermostatically controlled volume dampers and variable inlet vanes as a compromise to achieve system balance at the expense of energy consumption. The reduction of direct power costs on central fan systems through electrical speed control of eddy current drives is examined. In addition, several facets of the drive system will be evaluated in terms of centrifugal fan load applications. Simple payback analysis is also considered.