| 摘要 |
PURPOSE:To improve the precision of deterioration decision making by reading the residual charge of a cable to be measured as a continuous voltage by using a sector type electrostatic voltmeter. CONSTITUTION:This decision device consists of principally of a DC high voltage generating device 4 which charges a high DC voltage between the cable 1 to be measured and a shield 3, a high voltage switch 5 which opens a charging circuit when the charged voltage reaches a specific value, the electrostatic voltmeter 6 which measures the residual charge of the cable to be measured, and a computer 7 which decides whether the insulation of the object cable 1 is proper or not.The sector type electrostatic voltmeter 6 is constituted by fixing a high voltage electrode plate 14 on a panel 18, connecting a high voltage probe 20 connected to the high voltage electrode plate 14 to the object cable 1, and arranging a fixed electrode plate 15 opposite the voltage electrode plate 14. A movable electrode plate 16 is a disk which rotates according to the rotation of a coreless motor 21 and has a hole 22 with the same diameter with the fixed electrode 15, and when the hole 22 and fixed electrode 15 are superposed on each other, a voltage is induced at the fixed electrode 15 by electrostatic induction and the induced voltage is read by the computer 7.
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