| 摘要 |
PROBLEM TO BE SOLVED: To diagnose deterioration in the insulation of the outer coat of a power cable, without having to stop a high-voltage electricity-receiving facility. SOLUTION: A power cable insulation resistance recording device includes a superimposed voltage generator which applies an ultralow-frequency voltage between a metal sheath of a power cable 17 in a high-voltage electricity-receiving facility 18 and the ground; an ultralow-frequency AC insulation resistance meter 33, which measures the ultralow-frequency current and converts it into an insulation resistance; a direct grounding terminal 32, connected in parallel with the superimposed voltage generator which is closed during normal times so as to bypass the ultralow-frequency AC insulation resistance meter to ground the metal sheath of the power cable 17. A measurement timing circuit 35 opens the direct grounding terminal 32 with a predetermined constant cycle, when the current flowing between the metal sheath of the power cable 17 and the ground is equal to or lower than a predetermined value, and thereby causes the ultralow-frequency AC insulation resistance meter 33 to carry out a measurement operation so that a storage device 36 stores the values of insulation resistance measured by the ultralow-frequency AC insulation resistance meter 33, in a chronological sequence. COPYRIGHT: (C)2011,JPO&INPIT
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