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Energy Savings Using VFD's

Dustin Olson - Product Specialist

December 2018


What is a VFD? A variable frequency drive, also known as a VFD or Inverter, is a superior way of powering an AC induction motor when compared to powering directly across the line or with a soft starter. Some of the benefits gained by using a VFD include; smooth acceleration and deceleration, limited inrush current, higher motor efficiency, and operation at any frequency in the range of 0- 400Hz.

What are VFD’s used for? VFD’s are used to control the speed, torque and position of a motor shaft. They also provide many features to protect and prolong the life of your motor. VFDs are typically used for Fan, Pumping and Conveyor applications but can be used with any inverter rated AC Induction motor.

How can a VFD save energy? Motors applied to fans and pumps are typically oversized. Up to a 20% oversize is common due to NEMA motor power frame sizes and general engineering practice to add a small overhead. This 20% oversize provides an opportunity for users to save energy when applying a VFD. The VFD will allow you to run your motor at a speed that the application requires, that being less flow, slower speed, resulting in significant energy savings. The superior control of a VFD allows you to cut any unnecessary acceleration, decelerations and speed out of the motor’s motion which will save energy and reduce mechanical stress. For example in fan applications that use a mechanical dampener to restrict air flow. The damper can be opened fully and the speed of the motor can be slowed to reduce airflow, which will save energy instead of restricting the flow with a dampener and running the fan at full speed.