Variable Frequency Drives

One of the most successful energy management tools ever applied to building HVAC systems is the variable frequency drive (VFD). A Variable Frequency Drive (VFD) is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage.  Over the last four decades, VFDs have successfully been installed on fan and pump motors in a range of variable load applications. As technology has advanced, VFD cost and size has reduced and performance has improved through advances in semiconductor switching devices, drive topologies, simulation and control techniques, and control hardware and software. 

So why should you install a VFD in your facility?

1 – Reduce Energy Consumption and Energy Costs

Electric motor systems are responsible for more than 65% of the power consumption in industry today. Optimizing motor control systems by installing or upgrading to VFDs can reduce energy consumption in your facility by as much as 70%. Additionally, the utilization of VFDs improves product quality and reduces production costs. Combining energy efficiency tax incentives and utility rebates, returns on investment for VFD installations can be as little as 6 months.

2 – Extend Equipment Life and Reduce Maintenance

When an induction motor is started, it draws a much higher current than during normal operation. This inrush current can be three to ten times the full-load operating current for the motor, generating both heat and stress in the motor's windings and other components. In motors that start and stop frequently, this contributes to early motor failures. In contrast, when a motor connected to a VFD is started, the VFD applies a very low frequency and low voltage to the motor. Both the frequency and voltage are gradually ramped up at a controlled rate to normal operating conditions, extending motor life, and eliminating belt, gear and bearing wear. Because of the VFDs optimal control of the motor’s frequency and voltage, the VFD will offer better protection for your motor from issues such as electro thermal overloads, phase protection, under voltage, overvoltage, etc. It is also an excellent way to reduce and/or eliminate water hammer since smooth acceleration and deceleration cycles can be maintained.

3 – More Precise Levels of Control of Applications

Take, for example, a high-rise building and its use of a booster pump system on the domestic water supply to maintain adequate water pressure at all levels within the building. Conventional pump controls in this type of application can maintain the pressure within a certain range, but a VFD-based system can maintain more precise control over a wider range of flow rates, while reducing energy requirements and pump wear.

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SmartVFD HVAC2 standalone variable frequency drives (VFD) are designed to control HVAC motors and pumps up to 25HP to maximize energy efficiency. SmartVFD HVAC2 is a small footprint drive that can fit in your existing enclosure or become a NEMA 1 enclosure. SmartVFD HVAC2 drives can be mounted side by side with the proper free space for cooling airflow circulation.



SmartVFD HVAC is a standalone variable frequency drive (VFD) designed for use in HVAC applications to control the speed of HVAC pumps and fans in order to maximize energy efficiency. Smart VFD is also designed to run three-phase standard and high efficiency induction motors by varying the output voltage and frequency.


SmartVFD COMPACT is among the smallest, most streamlined energy saving variable frequency drives (VFD) available. An intuitive user interface lets you customize drive features to the application, eliminating waste and optimizing energy efficiency in HVAC pumps and fans. A free PC Tool with an optional adaptor turns your computer into a programming window to setup, control, monitor and diagnose in real time or for off-line editing and backup.