MICROPROCESSOR-BASED CATHODIC PROTECTION SYSTEM USING PHOTOVOLTAIC ENERGY

Cathodic protection (CP) is a means of rendering a metal immune from c orrosive attack by utilizing an external direct current to oppose the discharge of corrosion current from the anodic areas of the metallic s tructure. The variation of the surrounding medium's resistivity due to changes in climatic conditions makes it difficult to stop the corrosi on completely. So, the development of an automatic CP system is necess ary to overcome this difficulty. This work aims to automate the conven tional manually used impressed current method for buried steel pipelin es. The CP pipeline-to-soil potential difference will be adjusted auto matically and continuously using an electronic control system. This sy stem will manipulate the measured data concerning the CP and generate the required compensating current to stop the corrosion. The energy re quired for the electronic system will be obtained using photovoltaic a rrays. In the present paper, a complete design of a microprocessor-bas ed CP system using photovoltaic energy is given. The system consists o f: a photovoltaic (PV) array which generates DC power from solar radia tion, a storage battery of size sufficient to support the system by th e required energy for at feast two successive days, a charge controlle r to protect the battery against overcharging, and a microprocessor-co ntrolled circuit which enables one to make automatic adjustments for t he CP current according to the state of corrosion of the pipeline.