Variable Frequency Drives, also known as AC drives, are ubiquitous in applications utilizing electrical equipment. Their purpose in an electromechanical system is to control the speed and torque of an AC motor by changing the frequency and voltage of the input signal. They are used in applications that range from small compressors to large mill drives and industrial equipment.
While AC drives are commonly utilized for their energy saving potential, the exact amount of energy savings is based on the application. For example, in a centrifugal fan application, an AC drive can reduce energy costs ranging from 10 to 60 percent if the fan or pump is designed to operate between 40 to 80 percent of full speed, according to Siemens.