Investigation on Degradation Rate of XLPE Cable Laid under Dry Condition or with Water Barrier

Abstract

As XLPE cable laid in duct is mainly degraded by water-tree, water-tree growth and its affection to breakdown voltage of aged XLPE cable has been investigated. For XLPE cables laid under dry condition (substation, tunnel, etc.) or with water barrier, the growth rate of water-tree is considered to be lower than those laid in duct because of little water invading into the insulating layer. However, few reports related to this issue have been published and the degradation of aged XLPE cable laid under dry condition or with water barrier is not revealed. From these view-points, we investigated the breakdown voltage and the condition of water-tree degradation on removed 33kV XLPE cables laid under dry condition and with water barrier.