What is the primary purpose of a differential relay in electrical systems?

The primary purpose of a differential relay in electrical systems is to detect differences in current between two points. Differential relays compare the current entering a specific section of a system (such as a transformer or generator) with the current leaving that section. In normal operating conditions, the currents should be equal. However, if there is a fault, such as a short circuit within the protected zone, the current will not match, and the relay will sense this discrepancy.

This ability to identify faults based on current differences makes differential relays highly effective for protection schemes, ensuring that only the affected portion of the electrical system is isolated in case of a fault. This function is crucial in maintaining system stability and preventing equipment damage by ensuring appropriate actions are taken when abnormalities are detected.