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IAEI Magazine | Author: Mike Olson
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Mike Olson

Michael R. Olson is the HVAC Applications Manager Manager at ABB, Inc. Mr. Olson has extensive experience in the HVAC, Water/Wastewater Treatment, and Chemical markets. He has been applying adjustable speed drives to these and other markets for over 25 years. Mr. Olson has been published numerous times in trade journal articles discussing energy savings and the proper application of adjustable speed drives. He has a General Engineering degree from the University of Illinois and a Masters of Science in Engineering Management degree from the Milwaukee School of Engineering.

Articles

VFDs for Energy Savings in Hospitals – what they are, how they work, and how they save money

A variable frequency drive (VFD) is an electrical device we use to control the speed of a standard three-phase ac induction motor. The number of poles designed into a motor and the frequency applied to the motor determine the motor base speed. We can conveniently adjust the speed of a motor by changing the frequency applied to the motor. You could adjust motor speed by adjusting the number of poles, but this is a physical change to the motor. It would require rewinding, and would result in a step change in the motor’s base speed. So, for convenience, cost-efficiency, and precision, we change the frequency (and voltage). At any given frequency output of the drive, you get a new torque / speed curve from the ac motor.
JULY-AUGUST 2006