Abstract
In this study, the dielectric breakdown test was performed on the aged PVC insulated wires and the statistical life was estimated using the log-normal distribution probability. The sample is a 450 / 750V single-core PVC insulated wire collected from the inspection field. The AC dielectric breakdown test is conducted for three life groups of 0, 19, and 34 years to verify the change in the electrical insulation performance. The failure criterion assumes 50 % of the minimum design dielectric strength of IEC 60216-1, and the lifetime distribution is based on the lognormal distribution. The lifetime-dielectric breakdown voltage relation equation was derived from the linear fitting function of the percentile B50 of each life group. As a result, the breakdown voltage distribution by life group showed that the insulation strength of the IV wire decreased as the service life increased. As a result, three aging groups have shown that the insulation resistance performance of PVC insulators on IV wires decreases with longer service periods. And the life expectancy of PVC insulators of the IV wires according to the failure judgment criteria (50 ∼ 90 %) and failure rate (1 % and 50 %) is calculated from the relationship equation. As a result, the failure criteria and high failure rates confirm that the failure life is short.
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