Which item is a sign of overheating rotor bars?

Which item is a sign of overheating rotor bars?

• A. Reduced Starting Torque.
• B. Noise.
• C. Discoloration.
• D. All of the Above.

Answer: (C)

When rotor bars overheat, a clear, direct sign is discoloration on the rotor. The bars (typically copper or aluminum) heat up under excessive current or poor cooling, causing oxidation and color changes that you can visually spot on the rotor surface. This heat damage is a tangible indicator of overheating. Reduced starting torque and unusual noise can arise from a variety of motor problems, not specifically from overheated rotor bars, so they’re not as reliable as discoloration as a sign. Therefore discoloration is the best indicator of overheated rotor bars.

When rotor bars overheat, a clear, direct sign is discoloration on the rotor. The bars (typically copper or aluminum) heat up under excessive current or poor cooling, causing oxidation and color changes that you can visually spot on the rotor surface. This heat damage is a tangible indicator of overheating. Reduced starting torque and unusual noise can arise from a variety of motor problems, not specifically from overheated rotor bars, so they’re not as reliable as discoloration as a sign. Therefore discoloration is the best indicator of overheated rotor bars.