Which percentage range corresponds to a prolonged overload condition for Thermal Overload Relays?

A prolonged overload condition for Thermal Overload Relays is defined by operating at higher percentages of the Full Load Amperage (FLA). When the current exceeds the normal operating level, especially for a significant duration, it poses a risk of damage to the equipment.

The correct percentage range that identifies a prolonged overload condition is between 105% to 125% of the FLA. In this range, the relay is designed to monitor the heat generated in the motor resulting from the excess current draw. Since this condition indicates sustained stress on the motor, the relay will operate to protect the system by eventually tripping, preventing potential overheating and failure of the motor.

This choice accurately captures the threshold where the motor is experiencing increased thermal loads that could lead to detrimental effects if not corrected. The relay’s role is critical in ensuring that equipment remains operational within safe working conditions, thus preventing damage from extended exposure to overcurrent situations.