Conditions of a motor overload may be caused by which of the following?

• A. Overcurrent due to a jammed rotor
• B. Low voltage
• C. High ambient temperature
• D. All of the above

Answer: (D)

Motor overload happens when the motor heats up faster than it can be cooled, causing insulation and windings to be stressed. A jammed rotor leads to overcurrent because the motor cannot rotate, so back EMF stays low and current rises, generating excess heat. Low voltage makes it harder for the motor to develop the required torque, so it draws more current to try to run, which also increases heating. High ambient temperature reduces the efficiency of cooling, letting heat accumulate more quickly. Because any of these conditions can push the motor beyond its thermal limits, all of the above can cause overload.