One of the most common misunderstood aspects of applying variable frequency drives (VFD) happens when you retrofit a motor with a drive for the first time. Often the VFD purchased is too small. This happens when a person says, “I have a 10 hp motor so I need a 10 hp drive.”

The problem is that when you start a motor across the line, it has unlimited current from the starter powering it—this current creates the high torque needed to start the motor with its associated load.
Continue reading “Sizing Variable Frequency Drives” →