What is the primary function of a protective relay in an electrical system?

The primary function of a protective relay in an electrical system is to monitor electrical system parameters. Protective relays are designed to detect abnormal conditions such as overloads, short circuits, and equipment failures. When these conditions are identified, the relay activates to isolate the affected portion of the system, thus protecting both the equipment and the overall integrity of the electrical network.

By continuously monitoring parameters like current, voltage, and frequency, protective relays can quickly respond to faults. This action helps in preventing catastrophic failures, reducing the risk of fires, and ensuring the safety of personnel working within or near the electrical system.

The other choices, while related to the operation and functionality of various electrical devices, do not capture the main role of a protective relay. For instance, measuring voltage and evaluating power factor are tasks typically associated with measuring instruments rather than protective relays, while initiating maintenance activities falls under procedural aspects rather than the primary function of a relay focused on safeguarding the system during abnormal conditions.