WITHSTAND VOLTAGE TESTING METHOD AND DIAGNOSING METHOD FOR RUBBER AND PLASTIC INSULATION CABLE

摘要

PROBLEM TO BE SOLVED: To provide methods for withstand voltage test and diagnosing cables capable of surely finding harmful water tree without giving unnecessary degradation to the cables. SOLUTION: Very low frequency voltage with average voltage field of 5 kV/mm to 20 kV/mm is charged to a cable degraded by water tree for 10 to 100 minutes to test breakdown and generation of harmful water tree is judged for the breakdown cable and no harmful water tree and no lowering of AC remaining performance are judged by the test for no breakdown cables. Also very low frequency voltage with average voltage field of 6 kV/mm to 17 kV/mm is charged for 10 to 100 minutes to test breakdown and no life expectancy for 1 to 10 years is judged for the breakdown cable and the existence of life expectancy of 1 to 10 years and no lowering of AC remaining performance after the withstand voltage test are judged for no breakdown cables.