| 摘要 |
PROBLEM TO BE SOLVED: To provide a differential ratio relay which can prevent a malfunction even if primary side current and secondary side current of a transformer are input in a wrong direction and which can normally operate when an internal fault occurs in the transformer. SOLUTION: An arithmetic processing means 12 selects a first internal fault detecting means 10a when the polarities of the primary side current and the secondary side current are judged so that the polarities are reverse, selects a second internal fault detecting means 10b when the polarities have the same direction, and calculates to judge the fault of the transformer 3. The fault judged arithmetic result of the first detecting means 10a or the second detecting means 10b is output to an external unit via an external output means 13. A display means 14 displays the operating first detecting means 10a or the operating second detecting means 10b selected by the means 12. COPYRIGHT: (C)2004,JPO
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