Where are the overload heaters normally located in a motor circuit?

The correct placement of overload heaters in a motor circuit is within the motor starter, specifically situated between the T leads (load terminals) and the contactors. This positioning is crucial because overload heaters are designed to protect the motor from excessive current conditions that can lead to overheating. By being incorporated into the motor starter assembly, the heaters can effectively monitor the current flowing to the motor, allowing them to react when the current exceeds safe operational levels. In such a scenario, the overload heaters will trigger the starter to disconnect the motor from the power supply, thus preventing potential damage.

When considering other locations, placing the heaters in the control panel would not enable them to directly monitor the current intended for the motor. Similarly, housing them within the main motor frame would make it challenging to adequately respond to overload conditions and could complicate maintenance. Lastly, positioning the overload heaters at the power source would separate them from the area where they can effectively measure and react to motor current, thereby reducing their protective function. Thus, their placement in the motor starter is essential for effective overload protection and enhances the overall safety and functionality of the motor circuit.