Variable frequency drives (VFDs) are electrical devices that connect to a motor's electrical supply and change the frequency of the electricity that powers it. This regulates the motor's performance while lowering its energy consumption. In constant-torque and variable-torque applications, VFDs function with three-phase vector (inverter) motors. Like a conveyor belt, constant-torque applications maintain the same torque across their speed range. Variable-torque applications, such as fans, blowers, and pumps, will suffer surges and lulls in the load. There are two types of VFDs: open and enclosed. Open VFDs are stand-alone devices that can be installed in electrical cabinets or on the machine frame directly. VFDs that are enclosed are located in a panel with extra controls to monitor the VFD and save motor downtime. VFDs are employed in a variety of industrial operations, as well as water management and HVAC systems.