Wavelet packet analysis of the applied voltage waveform as a monitoring technique of the outdoor insulation surface

The objective of our study is to analyse the ac applied voltage signals recorded for different pollution levels using a following technique: wavelet packet analysis. Laboratory tests were performed on flat plate models of glass (500×500×5 mm) under uniform pollution. The plate models were sprayed with a solution prepared by mixing 100 g of kaolin in one liter of distilled water. An appropriate amount of NaCl was added to the slurry to give required Equivalent Salt Deposit Density (ESDD). The various studied ESDD are as follows: 1.2, 3.5, 6, 10, 15 and 20 mS/cm. The obtained results show that this technique constitutes a very effective tool to estimate the pollution severity degree on outdoor insulation surface.