| 摘要 |
PURPOSE:To forecast a dielectric breakdown of an insulator by utilizing the fact that the distribution of an electric charge being discharged presents a right-to-left symmetrical shape as approx. equilateral triangle in an intermediate area between the safe area and the dangerous area with respect to the dielectric breakdown and is opposite to it, presenting an inverted right-to-left symmetrical shape in the area before and after the area. CONSTITUTION:An AC voltage (e) is applied to a plastic insulator which is provided to cause an electric tree. Early in the generation of the electric tree, an average discharged free charge attributed to negative and positive pulse presents such a roughly right-angled triangle as to rise sharply at first and fall gradually. With the progress in the deterioration, it becomes gentle in the rising and finally presents such an equilateral triangle that the inclinations in the rising and the falling are symmetrical right to left. With further progress in the deterioration, it grows sharp gradually in the inclination of the falling and presents a roughly right-angled triangle utterly opposite to the shape of the distribution early in the generation of the tree. In other words, when the shape of the distribution is closer to the right-angled triangle, there is a less danger of a dielectric breakdown, when it is closer to the inverted right-angled triangle from the equilateral triangle, there is a higher possibility of danger thereof. This fact is utilized to fore-cast the dielectric breakdown of the insulator. |
