Study on DC component method for hot-line XLPE cable diagnosis

It is well known that water-tree is one of the main reasons of XLPE cable insulation aging. With the widespread use of XLPE cables, how to diagnose water-tree aging in insulation becomes more and more important. It has been found that a small DC component will be produced through the insulation of XLPE cables in service. By detection of this DC component, the degree of the cable insulation degradation can be examined, and hot-line diagnosis is realized as well. In this paper, according to a possible model of DC component production, research work of simulating hot-line diagnosis has been conducted with 10 kV XLPE cables in the laboratory. The experimental results indicate that the DC component is in good correspondence with the degradation caused by water trees