Which relay is most commonly associated with Substation Bus operations?

In substation bus operations, a differential relay plays a crucial role in protecting electrical equipment from faults. This relay is specifically designed to detect the differences in current between two or more points in the system. When operating correctly, it continuously compares the current entering and leaving the bus. If a fault occurs within the bus, such as a short circuit, the currents will not balance, leading the differential relay to activate, thereby isolating the affected area and preventing damage to other parts of the electrical system.

This capability makes the differential relay especially vital in protecting busbars, where multiple lines connect, and where faults can lead to significant disruption and safety hazards. On the other hand, the other relays listed, although essential in certain scenarios, do not serve the specific purpose of monitoring the balance of currents associated with bus operations as effectively as differential relays do.