A current-based solution for transformer differential protection. II. Relay description and evaluation

This paper describes a new approach for transformer differential protection that ensures security for external faults, inrush, and overexcitation conditions and provides dependability for internal faults. This approach combines harmonic restraint and blocking methods with a wave-shape recognition technique. We compare in the paper the behavior of some traditional transformer protection methods to that of the new method for real cases of magnetizing inrush conditions.