A Variable Speed Drive (VSD) is a type of motor control device that enables continuous regulation of a motor’s speed. VSDs provide the user with several advantages in terms of performance, reliability, and cost-effectiveness. A Variable Frequency Drive (VFD) is similar to a VSD, but instead of varying the speed, it varies the frequency of the AC supply to the motor. This enables finer control over the motor by offering better accuracy and efficiency than a VSD. Both VSDs and VFDs are used widely in industry for controlling motors, pumps, fans and other drives.