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XLPE-insulated power cables are known for their sensitivity to
water. Even a small water content in the insulation material
might lead to the growth of water-trees over a period of time,
and water-trees that have grown sufficiently large will lead to a
breakdown. The 500 Hz ageing test is a technique used to determine the
sensitivity of cables to water-trees. During this test a 500 Hz
voltage is applied to the cable while it is immersed in water. The
quality of the insulation material can be determined in just 4
months, since energizing the cable at 500Hz for 4 months is
equivalent to a lifetime of several decades at normal operating
conditions.
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