| 摘要 |
PROBLEM TO BE SOLVED: To provide an insulation monitor for well monitoring insulation degradation of a cable way by a simple structure. SOLUTION: A zero-phase-sequence current transformer 1 for a leakage relay is provided on a grounding wire of the cable way 5. To its secondary winding, a receiver 3 is connected to detect a leakage current. A capacitor device 4 of variable capacitance is attached to R and T phases of a non- grounding cable way, and the other end is grounded after it is wound as a primary winding of the transformer 1 for the leakage relay. The winding on the transformer 1 for the leakage relay of the capacitor device 4 is wound in such a winding direction that the phase of a current Ic flowing through the capacitor device is reverse to the phase of a leakage current Igc induced by ground capacitance Cgc1 and Cgc2 of the cable way 5. When the capacitance of the capacitor device 4 is set, a zero-phase-sequence current transformer 2 for a leakage ammeter is provided contiguous to the transformer 1 for the leakage relay. COPYRIGHT: (C)2004,JPO
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