Fig. 12: Flowchart of the proposed method for CUI monitoring.

Off-line stage involves baseline measurement and collecting ECN data from both uniform and localised corrosion systems for training the model to distinguish the two forms of corrosion. For the on-line monitoring, newly measured ECN data will firstly be processed to compare with the baseline to determine wet/dry condition of the insulation system. If wet condition is indicated, then the ECN data will be further examined using the model developed at the off-line stage to predict the dominant form of corrosion.