LIFETIME EXTENSION OF MEDIUM VOLTAGE CABLES

In many Austrian distribution grids PE-insulated medium voltage cables installed in the 1980's are still in service. Failures caused by water-trees in the insulation are well known and reported. For grid operators this raises the question of whether to replace the cables to maintain the reliability of the grid. Another possibility instead of replacing the cables is to extend the service life of PE-insulated cables using a treatment to refit the insulation. This treatment uses a silicon based fluid which is pressed into the insulation of the cable to inactivate existing water trees. Initially cables were treated using a fluid containing phenylmethyl-dimethyloxysilane components. These components often caused accelerated corrosion of aluminium conductors because of chemical reactions. Due to…