What essentially happens when a fault current occurs, and protective devices do not operate correctly?

When a fault current occurs and protective devices fail to operate correctly, significant damage can result to both the electrical devices involved and the overall installation. A fault current is an unintended current that flows through the system due to a fault, such as a short circuit or ground fault. Protective devices, like circuit breakers or fuses, are designed to interrupt the flow of this fault current to prevent overheating, electrical fires, and equipment damage.

If these protective devices do not function as intended, the excess current can lead to overheating wires, insulation breakdown, and possible arcing, which can cause permanent damage to equipment, including motors, transformers, and other electrical apparatus. The structure of the electrical installation can also be compromised, leading to more extensive repairs or even a complete overhaul of the system. This highlights the critical role of protective devices in safeguarding electrical systems from the adverse effects of fault conditions.