What is the term "thermal overload" in motor protection referring to?

The term "thermal overload" in motor protection specifically refers to excessive heat generated within the motor due to high current flowing through its windings. When a motor operates under conditions that lead to an increase in current—such as a mechanical jam, overloading, or improper voltage supply—more electrical energy is converted into heat. This excessive heat can exceed the motor's design limits and lead to insulation breakdown, component failure, or even complete motor burnout.

Motor protection mechanisms, such as thermal overload relays, are crucial because they monitor the temperature of the motor; if it reaches an unsafe level, the relay will disconnect power to prevent damage. Thus, understanding thermal overload risks and protection methods is fundamental in ensuring the longevity and reliability of electric motors.