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Abstract

The evaluation of latest test results on XLPE high voltage cables leads to the same insulation thickness for 500 kV as it did a few years ago for 400 kV. The reason is given by progresses in material and production technologies resulting in more homogeneous electrical properties of the present cables as compared to the former ones. This holds true above all for the breakdown behaviour under impulse and under ac test conditions. There has been noticed a marked increase of the lower breakdown strength limit (impulse), and the evaluation of recent long term tests at ac voltage and load cycles justifies the conclusion that there seems to be no electrical ageing, provided that water is excluded. 500 kV cables with an insulation thickness of 30 mm corresponding to a maximum operating gradient of 15.5 kV/mm have been successfully subjected to first type tests, and they fulfill any safety requirements as published in the literature or specified by some national standards.

Modified Last : 26/09/2008