Study of ion migration in insulator subjected to DC voltages

摘要

Ion migration test suggested in IEC 1325. 1995 forrnHVDC insulators takes into consideration the totalrncharge that would have passed through the volume ofrninsulator in its estimated life of 50 years. This isrnallowed to pass through the insulator in anrnaccelerated manner within few thousands of hours orrnso. Ion migration tests were carried out on fewrnbatches of HVDC insulators. The expected chargernQ50 and number of days for the test was evaluated asrnper IEC-1325, 1995. The ready reckoner of productrnof Q50 and R90 v/s temperature coefficient A wasrnevaluated which can be used to evaluate Q50rnexpeditiously. Though the insulators have higherrnvalues of resistance and better slopes, the testrnduration is higher. The insulators having lowerrnvalues of resistance and lower values of slopes havernless number of test days.