About the Technology: Electronic Adjustable Speed Drives (ASDs) are devices that can greatly improve the efficiency of ac motors in applications with highly variable loads. ASDs, also known as variable speed drives and variable frequency drives, save energy by matching motor speed (and electricity used) to load, rather than restricting the load itself by means of throttling using valve and dampers. ASDs precisely control the electricity going to the motor.
The best uses of ASDs are for fans, pumps, and other fluid systems. Savings of up to 50% can be achieved with ASDs properly installed on fan motors, and up to 75% on pumps. In addition to energy savings, ASDs increase motor and system life and present an unparalleled degree of control over the motor system. Especially for motor systems dealing with fluids, this allows changes to be made to fit changing conditions faster and more efficiently.
Currently, only 4% of manufacturing motor system energy use is equipped with ASDs. It has been estimated that motors representing 14% of total manufacturing motor system energy can cost-effectively utilize ASDs. This amounts to 252,000 motors.
Payback Periods for ASDs: Payback periods for ASDs will vary by motor size and application. Average paybacks for fans are less than 3.5 years for motors 350 hp and larger. Average paybacks in pump applications range from 3 years for 75 hp motors and just over one year for motors above 750 hp.
Energy, Cost, and Environmental Savings: If all cost-effective ASD applications were undertaken, U.S. manufacturers would save (compared to the current motor stock) 21,500 GWh annually, worth about $949 million. This would also avoid 14 million tons of carbon dioxide emissions.
The ASD Market and Employment: According to the 1992 Census of Manufacturers, about 61,600 people are employed in manufacturing relays and industrial controls, which includes ASDs. In 1997, the total value of all products in this industry was $7.6 billion. Of this, the total value of ac adjustable speed drives and related controls was $574 million. We estimate the number of people involved in manufacturing ASDs to be about 4,650. If the total number of ASDs were increased at the rate we calculate, it is concluded that there would be a modest but significant gain of 385 jobs in this sector.
In addition, if electronic Adjustable Speed Drives captured all the potential market, motor manufacturers could gain almost $50 million dollars in additional revenue annually.
Contact: Dr. Douglas Norland, Director of Research.