| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground relay which can surely detect the ground fault, on the side of a single-phase power source and moreover, which will not operate needlessly to a heterogeneous-phase-mixed-contact fault on the side of a single-phase power source. SOLUTION: This relay inputs the first potential VA1 and VB1 and the second potential VA2 and VB2 in each pair where each potential across two pairs, A seat and B seat, of single-phase power sources is divided equally in potential to the ground by means of an input means 21, and obtains effective component differencesΔwa andΔwb in each pair which arise at ground fault time, on the side of the single phase power source from the first and second potential values in each pair and these phase difference anglesϕ1 andϕ3 by means of a phase calculating means 25; and when any of them exceeds this actuation detected value, since this decides that it is a ground fault by means of a comparison deciding means 26, the ground fault can be surely detected, without operating unnecessarily, with respect to the contact fault involving heterogeneous phase mixing. COPYRIGHT: (C)2005,JPO&NCIPI
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