In the event of a fault in the power system, what will the System Operator look for?

In the event of a fault in the power system, the System Operator specifically looks for conditions that lead to abnormalities that can trigger protective measures to ensure reliability and safety. The correct answer addresses a scenario where there is abnormal electric current that not only deviates from standard operational norms but also reaches a level significant enough to activate protective relays. This is critical because protective relays serve as safety mechanisms designed to isolate faults and protect both the equipment and the integrity of the electrical system.

When abnormal electric current occurs, it indicates an underlying issue in the system, such as a short circuit or ground fault, and it is essential for the operator to detect these currents promptly. The operation of protective relays ensures that the system can automatically respond to such faults, thereby preventing potential damage to equipment, maintaining operational stability, and ensuring safety.

The other options may describe related concepts but do not encapsulate the critical nature of protective relays responding to a specific condition of abnormal electric current that signifies a fault needing immediate attention. Therefore, the emphasis on the relay operation in the correct choice highlights an essential aspect of fault management in power systems.