Final answer:
The thermal overloads in a motor starter serve the specific purpose of providing motor overload protection. They sense excessive heat generated by too much current and disconnect the motor to prevent damage. Thermal overloads are resettable, differing from one-time-use fuses and are not the same as circuit breakers or GFIs.
Step-by-step explanation:
The specific purpose of the thermal overloads in a motor starter is d) Motor overload protection. These safety devices are designed to protect an electric motor from overheating due to an overload condition. They function by sensing the amount of heat generated by the motor, which correlates to the electrical current passing through the motor. When the current exceeds the motor's rated capacity, the thermal overload will open the circuit and stop the flow of electricity, thus preventing potential damage to the motor. This action safeguards the motor from the adverse effects of prolonged overcurrent which can lead to excessive heating and eventual motor failure.
It's important to note that thermal overloads differ from devices like circuit breakers and fuses, which are intended to interrupt excessive currents to prevent thermal hazards, and from ground fault interrupters (GFI) which are designed to protect against shock by detecting the loss of current to unintentional paths. Unlike fuses, which need to be replaced once blown, thermal overloads can typically be reset after tripping.