What is the role of a differential relay in power systems?

The role of a differential relay in power systems is primarily to detect imbalances in current flowing through a circuit or system. This type of relay is designed to compare the current entering a protected zone with the current leaving that zone. Under normal operating conditions, these currents should be equal. However, if there is a fault, such as a short circuit or a ground fault within the zone, the currents will differ. The differential relay senses this difference, known as differential current, and acts by tripping the circuit to protect the system from damage.

By focusing on current imbalances, differential relays provide critical protection for equipment such as transformers and generators, ensuring that faults are quickly isolated and do not lead to more severe failures. This functionality is crucial in maintaining the stability and integrity of power systems.

The other options confuse the primary function of the differential relay with the roles of other types of relays. For instance, monitoring phase angles is related to synchrophasor technology, while preventing overcurrent conditions is typically handled by overcurrent relays. Managing voltage levels falls under the purview of voltage relays or automatic voltage regulators. The specific capability of detecting imbalances in current is what makes differential relays essential for safeguard mechanisms in electrical installations.