What does the Reverse Power Relay indicate?

The Reverse Power Relay is a protective device designed to monitor the direction of power flow in electrical systems, particularly in generator applications. When the system operates normally, power flows from the generator to the bus or load. However, in certain scenarios, such as when the generator is operating at a low output and the load is less than what is required, or if there is a fault, power can flow in the reverse direction—from the bus back to the generator.

Option C accurately reflects this important functionality of the Reverse Power Relay, indicating a flow of power in the reverse direction, which signals that the generator is being driven by the bus voltage rather than supplying power. This situation can potentially be harmful to the generator if it is not addressed, as it can lead to damage over time or operational failure. The relay helps ensure the system operates safely by detecting this reverse flow and providing protective action if necessary.

Other options might point to different system events, but they do not specifically capture the critical role of detecting reverse power flow, making option C the correct choice.