| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground fault detection system which can be used for a DC circuit connected to an AC distribution system and includes a simpler, lower-cost structure than that of conventional ones. SOLUTION: A ground fault detection system 40 for a DC circuit 30 includes a voltage transformer (EVT) 41 for a grounding type gauge connected to a non-grounded three-phase AC system bus bar 13; and a zero-phase current transformer (ZCT) 51 for AC provided in the DC circuit 30. For a ground fault of the DC circuit 30, a 3n harmonic exciting current (n is an odd number of 1 or larger) is circulated between the EVT 41 and a fault point Fd through the ground due to the nonlinearity of magnetization characteristics of an iron core of the EVT 41. The ZCT 51 detects this 3n harmonic current. A capacitor 50 is provided between a neutral point 44 of a primary winding of the EVT 41 and a ground electrode 59. COPYRIGHT: (C)2011,JPO&INPIT
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