Microprocessor-based cathodic protection system using photovoltaic energy

Cathodic protection (CP) is a means of rendering a metal immune from corrosive attack by utilizing an external direct current to oppose the discharge of corrosion current from the anodic areas of the metallic structure. The variation of the surrounding mediumʹs resistivity due to changes in climatic conditions makes it difficult to stop the corrosion completely. So, the development of an automatic CP system is necessary to overcome this difficulty. This work aims to automate the conventional manually used impressed current method for buried steel pipelines. The CP pipeline-to-soil potential difference will be adjusted automatically and continuously using an electronic control system. This system will manipulate the measured data concerning the CP and generate the required compensating current to stop the corrosion. The energy required for the electronic system will be obtained using photovoltaic arrays. In the present paper, a complete design of a microprocessor-based CP system using photovoltaic energy is given. The system consists of: a photovoltaic (PV) array which generates DC power from solar radiation, a storage battery of size sufficient to support the system by the required energy for at least two successive days, a charge controller to protect the battery against overcharging, and a microprocessor-controlled circuit which enables one to make automatic adjustments for the CP current according to the state of corrosion of the pipeline.