Every AC induction motor needs an electrical control device to start and protect it. Selecting the optimal method of motor control is best approached by considering the connected equipment and what the application demands are.
Some processes need to accelerate gradually to full rated speed and then continue to run at constant speed until the process is finished. Others may require the speed to vary continuously throughout the process cycle, accelerating and decelerating at predictable, repeatable ramp rates.
Two commonly used motor control devices are the Variable Frequency Drive (VFD) and the Reduced Voltage Soft Starter. Each has advantages and disadvantages. This whitepaper discuss the similarities and differences of these two motor controllers and how to determine which of them will best suit your application needs.