Imbalance in a rotating machine can indicate which of the following issues?

• A. Worn bearings
• B. Electrical short circuit
• C. Balanced impeller
• D. Proper lubrication

Answer: (A)

Imbalance shows up as vibration from unequal mass distribution in a rotating part, causing centrifugal forces that pulse as the shaft spins. When bearings wear, they allow more radial play and can let the rotor tilt or run eccentrically. This off-center motion amplifies or reveals an imbalance, producing noticeable vibration. So worn bearings are a plausible cause of imbalance because they create the conditions that let the rotor behave as if its mass is unevenly distributed.

Electrical short circuits are electrical faults, not mass distribution issues. A balanced impeller would not cause imbalance—in fact, it would prevent it. Proper lubrication helps bearings and reduces wear, but it doesn’t create or signal an imbalance.