| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for solving the problem of a transformer protection relay using a current differential relay, which is operated with aΔdifferential current (Id) being able to identify an internal or external fault of a transformer but results in mis-matching between a relay operation profile and the actual phase of the fault, due to the correspondence to the amount ofΔ-quantity differential current (Id) and moreover if a user desires information regarding the actual phase of the fault, the operation profile of the current differential relay calculated with theΔ-quantity differentia current is insufficient and has a possibility of generating confusion. SOLUTION: The relay is constituted such that a two-phase operating condition, a three-phase operating condition and a single-phase operating condition due to a current differential relay operation output which calculates theΔdifferential current (Id) as the operation amount are, formed respectively; when the single-phase operating condition is set, the calculation phase of the relevant current differential relay is discriminated as a fault phase, and when the two-phase operating conditions are set, the phase common to the calculation phase of the relevant current differential relay is discriminated as being fault phase; and when the three-phase operating condition is set, the phase is discriminated as being the three-phase fault and these faults are displayed on the external circuit.
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