| 摘要 |
PROBLEM TO BE SOLVED: To measure an insulation resistance altogether with a circuit branched from a main circuit in a live state. SOLUTION: In an insulation level monitoring device for direct current for measuring an insulation resistance of a DC circuit provided with the main circuit 2 having a DC source 1 and a plurality of circuits A<SB>M</SB>branched from the circuit 2, a switch 3 for making a switch to allow a current to flow through the insulation resistance of either a positive side electric path S<SB>PM</SB>or a negative side electric path S<SB>NM</SB>of the circuit A<SB>M</SB>by a circuit voltage of the source 1 is provided on the main circuit 2, a zero-phase current transformer CT<SB>M</SB>for DC for detecting a current flowing through the insulation resistance of the electric path S<SB>PM</SB>or the electric path S<SB>NM</SB>of the circuit A<SB>M</SB>by switching of the switch 3 is provided on each of the circuits A<SB>M</SB>, and the insulation resistance of the electric path S<SB>PM</SB>or the electric path S<SB>NM</SB>is individually measured on the basis of the current flowing through the insulation resistance. COPYRIGHT: (C)2004,JPO
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