In what kind of circuits is overload protection usually required?

Overload protection is particularly essential in high current motor circuits, primarily because these circuits are associated with devices that can draw significant amounts of current during normal operation as well as during startup. Motors, especially, can experience high inrush currents that exceed their normal operating current, which can lead to overheating and potential damage if not adequately protected.

In high current motor circuits, overload protection devices, such as overload relays or fuses, are used to detect conditions where the current exceeds the safe operating range and disconnect the power supply to prevent damage. This is critical for maintaining the longevity and safety of both the motor and the circuit in which it operates.

Other circuit types, such as low voltage signaling circuits, power supply circuits, and communication circuits, typically operate at lower current levels and do not experience the same risks of overloading as high current motor circuits. Therefore, while protection might still be necessary in these circuits, the specific need for overload protection is most pronounced in high current motor circuits.