Can a response control vane axial (VRD) be used with a variable frequency drive?
Before trying to understand the results of using a response control vane axial with a variable frequency drive, it is important to understand the abilities of these controls when used on their own. A response control vane axial, or VRD, uses the fan’s ability to adjust the impeller pitch in-flight to control the performance. A variable frequency drive is typically used with a constant pitch fan and adjusts the fan RPM to control the performance. When used together in a well designed system, it is possible to have a very controlled and stable volume and static pressure output. On the other hand, the combination of response control and a variable frequency drive could lead to unstable performance, fan surging, and overall customer dissatisfaction of the fan – whether the fan is the problem or not. Our recommendation is to avoid using a response control vane axial with a variable frequency drive. If a variable frequency drive is required, we recommend using an adjustable pitch vane axial