A negative sequence relay is used to identify what condition?

A negative sequence relay is specifically designed to detect unbalanced conditions in three-phase systems, which typically occurs when there is an unequal distribution of load among the phases. This situation can arise, for example, when a generator is supplying an unbalanced load. The negative sequence current reflects the imbalances in the current flowing through each phase.

When one phase carries less current than the others, the negative sequence relay will sense this discrepancy and trigger an alarm or protective action to prevent damage to the generator or motor involved. This is crucial because unbalanced loads can lead to overheating, vibrations, and ultimately failure of the equipment.

Understanding this function helps ensure that electrical systems operate efficiently and safely while protecting both the equipment and the electrical infrastructure. Therefore, the use of negative sequence relays is primarily associated with identifying conditions related to generators supplying unbalanced loads.