How can motor overload be detected in operation?

• A. Compare actual current to FLC; monitor temperature or thermal sensors; inspect for excessive heat or vibration.
• B. Check the motor’s RPM only.
• C. Rely on the motor nameplate rating exclusively.
• D. Ignore thermal symptoms and assume the load is within limits.

Answer: (D)

Motor overload shows up as heat and electrical demand beyond what the motor can safely handle, so you detect it by watching real-time indicators rather than just speed or a nameplate value. The primary signal is the actual current drawn compared to the motor’s full-load current; if the current is higher than expected for the load, the motor is being overloaded. Thermal monitoring—using winding thermistors or RTDs and temperature sensors—reveals overheating that can damage insulation if not controlled. Vibration and unusual mechanical symptoms can also accompany overload, pointing to excess load or binding that increases current and heat. Temperature and current together give a reliable picture of operating limits being exceeded, whereas relying on RPM alone or the nameplate rating does not provide real-time protection—nameplate ratings are static and don’t reflect dynamic conditions. Ignoring thermal symptoms and assuming the load is within limits defeats the protection strategy and increases the risk of damage.