Deterioration Characteristics of Insulating Paper for Pole Transformer at Higher Temperature Loading

Abstract

Deterioration of insulating paper for pole transformer has been examined by accelerated aging test to around 200°C. However, its deterioration behavior at higher temperature loading should be studied separately because of the different decomposition reactions. At temperature range between 300-400°C, the weight loss is significant and reached over 70% with increase of the carbon content, which could be functional as an indicator to estimate deterioration at high temperature. The insulation resistance was rather increased at 300°C and decreased over 400°C along with carbonization. On the other hands, the tensile strength was quickly weakened even with heating for 1, 5, 10 min at 300°C, suggesting that physical damage of the paper occurs much faster than the loss of the insulation property. The damaged paper would be easily teared, increase sludge in transformer, and be a potential reason for insulation breakdown.