What is VFD? | Variable Frequency Drive Explained What is VFD (Variable Frequency Drive)? A VFD (Variable Frequency Drive) is an essential device in modern motor control systems. It regulates the speed, torque, and energy efficiency of electric motors by controlling the frequency and voltage supplied to them. VFDs are widely used in industrial automation , HVAC systems , pumps , and commercial machinery to enhance process efficiency and reduce power consumption. How Does a VFD Work? A VFD controls motor speed and performance by adjusting the power frequency supplied to the motor. This allows for smooth start-up , speed regulation , and energy-efficient operation based on process requirements. In most industrial setups, the VFD is used to: Control motor speed or pump flow rate as per demand Accept analog input signals (such as 4–20 mA or 0–10 V) for automatic speed control Provide protection features such as open-wire detection, trip alarms, o...