What is a VDF?
VFDs convert a fixed-frequency supply voltage (60 Hz in North America) to a continuously variable frequency. By controlling the frequency of the voltage supplied to an AC motor, we can control its rotational speed and minimize the stress applied to said motor. A VFD can control two main elements of a 3-phase induction motor: its speed and torque.
Motor-driven systems are typically designed to operate at peak load. This leads to energy inefficiencies when a system is running at a reduced load over time. A variable frequency drive gives an operator the ability to adjust the speed of the motor, matching the motor output and load requirements, thus resulting in energy savings.
VFDs are used for two main reasons:
Why use a VDF with your blower motor?
The rate of rotation for an industrial blower’s blades is driven by its motor speed; even a small reduction in speed can result in significant energy savings.
The blower affinity laws govern the relationship between rotation speed, flow, and power. The laws state that:
Therefore, in a practical application where speed has been reduced to 75 percent of the design speed:
Besides saving energy, VFDs are also used to:
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