抄録
In the DC component method, one of the typical method for insulation diagnosis of 6.6kV live cables, the mechanism for evolution of DC component current is closely associated with the detecting sensitivity to water trees. However, the mechanism is not yet fully understood. So that, we studied on the mechanism and the effectiveness of the DC component method by XLPE cable model. The experimental results indicate that the origin of DC component current is the apparent electromotive force, nearly 0.1V, and arises from the weak rectifying effect on the interface of moisture in semiconducting layer and Cu2O on corroded shielding tape. The dependence of DC component current on AC electric field seems to be explained on Poole-Frenkel mechanism. The DC component current which arises from the electromotive force is nearly 10pA per one water tree under AC electric field of 1.1kV/mm.
