| 摘要 |
Provided is a current differential relay apparatus, wherein malfunctions of apparatuses are prevented by letting the relay continue the function thereof even when saturation of a current transformer occurs due to an internal accident. A ratio differential characteristic evaluation unit (14), which is for evaluating a ratio differential characteristic functioning on the basis of the amount of operation (Id) and the amount of inhibition (Ir), comprises: a first current-range evaluation unit (14-1) that evaluates, when a relationship of a 1 ‰¤ a 2 and b 1 ‰¥ b 2 holds true wherein a 1 , a 2 , b 1 , and b 2 are real numbers, that a functioning thereof be implemented when Id > a 1 Ir + b 1 ; a second current-range evaluation unit (14-2) that evaluates that a functioning thereof be implemented when Id > a 2 Ir + b 2 ; and an AND operation unit (14-3), a reset unit (14-4), and a flip-flop unit (14-5) that evaluate that a ratio differential characteristic functioning be implemented when evaluations are made at both the first and second current ranges that functioning thereof be implemented, and makes the functioning thereof be continued until the functioning at the first range is reset. |
