Modelling of Electric Field Distributions on Cable Termination Defects under DC Plus Ripples

Cross-linked polyethylene (XLPE) cables are widely employed in high voltage transmission and medium voltage (MV) distribution networks due to the ease and low cost of forming the XLPE. However, defects in XLPE cable accessories such as joints and terminations will increase the local electric field and produce electrical discharges that erode the cable insulation and eventually result in the insulation failure. This paper develops finite element models to simulate small semicon tip defects at cable terminations and their resulting electric field distortion under MVDC stress voltage plus low frequency ripples. The influences of semicon tip lengths, ripple content and cable temperature gradients on electric field distributions are investigated to understand the electric field distortion surrounding semicon tip defects in relation to practical operation of MVDC XLPE cables.