Corrosion prevention of aluminum screens of underground HV/MV power cable

摘要

Corrosion prevention of Aluminum screens of MV/HV underground power cable is described in this paper. In presence of cable outer sheath breach, the Aluminum screens will be exposed to corrosive media. In such a way a galvanic coupling of the screen wires with the ground from one hand, and AC corrosion due to the passage of part of capacitive current through the defect on the other hand may cause corrosion of Aluminum. The corrosion prevention solution described in this paper comprises of two techniques: a new corrosion inhibitor developed by Prysmian —, and cathodic protection system to avoid an induced corrosion of Aluminum by AC interference. Uncertainties still exist on protection potential interval when AC interference is present, and on protection current density to reach acceptable protection. As far as the cathodic protection is concerned, a field test was carried out to insure the effectiveness of CP in presence of AC current, and to investigate the following design parameters: Effectiveness of a passive CP system while the Zinc anode is simultaneously connected to the ground bed and Al screens,Necessity of using a SSD system or polarization cellThrowing power of anode, and Corrosion rate of Anode in presence of AC current and ground bed connectionAC current threshold for application of CP systemCorrosion prevention of Al in presence of AC current.