Question 339Electricity & Electronics - QMED

The correct answer is C) overload relay thermal heater. The "OL" symbol on lines T1 and T3 in the power circuit diagram (figure "A") represents the overload relay thermal heater. The overload relay is a protective device that monitors the current flowing through the motor circuit. If the current exceeds a certain threshold, indicating an overload condition, the thermal heater will cause the overload relay contacts to open, interrupting the power supply to the motor and preventing potential damage. The other options are incorrect because: A) a fusible link is a different type of protective device, B) the overload relay contacts are normally closed, and D) the magnetic coil is a separate component within the overload relay assembly.