What is the role of overcurrent protective devices?

The role of overcurrent protective devices is primarily to prevent overloads and short circuits within electrical systems. These devices, which include fuses and circuit breakers, are designed to detect excessive current flow that could lead to overheating or damage to electrical equipment.

When the current exceeds a predetermined threshold due to an overload (where the equipment is drawing more current than it is rated for) or a short circuit (a fault condition where electricity flows along an unintended path), the protective device automatically interrupts the circuit to prevent further damage. This action not only protects the electrical infrastructure but also enhances safety by reducing the risk of fires and equipment failures.

The other options presented relate to different functions within electrical systems. Enhancing energy efficiency pertains to reducing energy waste, which is not the primary function of overcurrent protective devices. Controlling voltage levels involves voltage regulation, which is managed by different devices such as transformers and voltage regulators, rather than overcurrent protection. Increasing system capacity refers to expanding the capability of an electrical system to handle more load, which is also not directly related to the function of overcurrent protective devices. Hence, preventing overloads and short circuits accurately describes the core role of these protective devices.