Ramp-up in a VFD-controlled motor refers to:

• A. The rate at which motor speed increases from a stop
• B. The rate at which motor speed decreases
• C. The constant speed segment
• D. The maximum speed

Answer: (A)

Ramp-up is the rate at which the motor speed increases from standstill when using a VFD. The drive gradually raises the output frequency and voltage over a programmed acceleration time, giving a smooth start instead of an abrupt jump to full speed. This helps limit inrush current, reduces mechanical stress on the motor, drive, and driven load, and minimizes issues like belt slip or stall. It is different from ramp-down, which is the deceleration phase, and from the constant-speed segment, where the speed is held steady, or from the maximum speed, which is simply the top speed the system can reach. So ramp-up specifically describes how quickly the motor accelerates from zero.