Speed controller harnesses rare-earth magnets to save energy

Sept. 27, 2001
Industrial motors consume about 25% of all the electricity generated in the U.

Industrial motors consume about 25% of all the electricity generated in the U.S. To take a bite out of that figure, engineers at Seattle's MagnaDrive Corp. have developed the Adjustable Speed Drive to tightly control a motor's speed while under load. The ASD, a nonelectric device, mounts between a motor and its load, usually a pump, fan, or blower

It consists of two basic components: a rotor with permanent rare-earth magnets mounted on the load shaft; and a copper conductor assembly connected to the motor shaft. The components do not physically contact each other. Instead, relative motion between them creates a magnetic field that transfers torque from motor shaft to the load. In effect, the pull between magnets on the load side and copper on the motor side creates the coupling force. Changing the gap width alters the coupling force, so torque transmitted between motor and load can be continuously adjusted. This lets users precisely control speed, conduct "soft" starts and stops, and make more efficient use of their power. Field installations show the MagnaDrive ASD can cut energy consumption from 30 to 66%. And because there are no physical connections between the motor and load, no vibrations travel from motor to load or from load to motor, reducing wear and tear.

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