A VFD's ability to maintain performance through the full speed range is described as maintaining what?

A VFD's ability to maintain performance through the full speed range is described as maintaining what?

• A. RPMs
• B. Locked rotor current
• C. Full torque
• D. Nameplate FLA

Answer: (C)

A VFD keeps the motor’s flux essentially constant by controlling voltage and frequency, so the motor can deliver its rated torque across speeds. Because torque is tied to current, the drive maintains the rated current level as speed changes (via the V/Hz relationship up to the base speed). That ability to deliver the same torque over the speed range is described as maintaining full torque, which keeps the load’s performance consistent. Beyond the base speed, the drive typically limits torque to preserve constant horsepower, so the “full torque” behavior primarily applies up to the rated speed.

A VFD keeps the motor’s flux essentially constant by controlling voltage and frequency, so the motor can deliver its rated torque across speeds. Because torque is tied to current, the drive maintains the rated current level as speed changes (via the V/Hz relationship up to the base speed). That ability to deliver the same torque over the speed range is described as maintaining full torque, which keeps the load’s performance consistent. Beyond the base speed, the drive typically limits torque to preserve constant horsepower, so the “full torque” behavior primarily applies up to the rated speed.