Effect of aging of breakdown voltage of artificially damaged cable

The effect of flaws and thermal and radiation aging of flaws on the electrical breakdown of low-voltage cable was studied. AC breakdown voltages of XLPE (cross-linked polyethylene) and EPR (ethylene-propylene rubber) cables were measured for both damaged and undamaged cable. Three types of flaws were studied: scrapes, transverse cuts, and longitudinal cuts. Some cables were radiated-aged up to 1 MGy and others were thermally aged at 130/spl deg/C for up to 50 days. Results to date indicate little effect of aging on breakdown voltage and a linear decrease in breakdown voltage with decreasing thickness beneath scrapes and transverse cuts below some threshold thickness. Calculated electric field distributions at breakdown indicate that breakdown occurs by partial discharge in pores.<
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