Cable deformation and electric field distortion of submarine cable insulation caused by anchoring impact

Anchor damage is one of the most significant failure modes in submarine cable. Generally, it is difficult for anchor impact to cause an immediate cable broken and fault due to the buried depth under the seabed. However, majority of the anchor can penetrate into the seabed and cause the cable deformation. It presents little influence on the power transmission but affects the electrical performance and the lifetime of submarine cable. In this paper, the electric field distortion of submarine cable insulation on the basis of the cable deformation caused by anchor impact was studied. The cable deformation characteristics was obtained by simulation of anchor impacting in a 35 kV AC submarine cable. The relative permittivity, conductivity as well as dielectric loss of insulation caused by the effects of residual stress were considered. An obvious deformation occurred in the insulation near the anchoring impact region, which causes the local electric field distortion. The simulation results indicate that the increase of insulation electric field is not only due to the deformation of insulation, but also the decrease of relative permittivity. Meanwhile, the space charge in the insulation also increases in the deformed insulation layer, which probably enhance the degradation of cable insulation. This paper provides a correlation between the anchor damage and the cable insulation performance for submarine cable.