What is the definition of a Variable Speed Frequency Drive (VFD)? A VFD is an electronic device used to regulate the speed of an electric motor by controlling the frequency and voltage of the power supply. It is also known as an adjustable-speed drive, adjustable-frequency drive, or variable-frequency drive. The VFD is used to control the speed of the motor, which allows for more accurate and efficient operation. This helps to reduce energy costs and reduce the amount of maintenance required for the motor. It can also be used for applications such as controlling the speed of pumps and fans. VFDs are often used in industrial applications, such as controlling the speed of conveyor belts, pumps, and other machinery. Some VFDs can also be used to increase the efficiency of pumps and fans, by allowing the motor to operate at a higher speed while consuming less energy. In addition, some VFDs can be used to reduce noise and vibration from motors and other machinery