During dynamic balancing, what measurement would indicate the rotor is balanced?

• A. Minimal phase-corrected vibration amplitude at the balancing plane
• B. Maximum vibration amplitude
• C. Random vibration fluctuations
• D. High temperature at the rotor

Answer: (A)

Dynamic balancing is about canceling out unbalance so the rotor’s vibration response disappears as much as possible. The key indicator is the vibration measured at the balancing plane, but with its phase referenced correctly to the rotor so you know exactly where the imbalance is relative to the sensor. When balance is achieved, that phase-corrected vibration amplitude at the balancing plane reaches a minimum, meaning the unbalance components have been neutralized and no additional correction is needed. If you saw maximum vibration, random fluctuations, or high temperature, those are signs of remaining unbalance, measurement noise, or overheating, not a balanced rotor. So the best indicator of balance is the smallest phase-corrected vibration amplitude at the balancing plane.