Effects of Loading Factor on the Condition of Insulating Paper in Power Transformer

The power transformer is one of the most important equipments that has a critical role in good electrical power delivery. Ageing of paper insulation inside the transformer is irreversible and hugely related to the operation of power transformer. This study involved inspection data from in-service and out-of-service 150 kV power transformers provided by the Indonesian electric company. The degree of polymerization (DP) of the cellulose paper insulation and furanic compound in the insulating oil can be used to estimate the transformer's lifetime. In this study, the correlation between HI decreasing rate (HI dec_rate ) and the loading factor of 115 transformers historical data was observed. The DP of the transformer paper was predicted (DP pred ) using the ANFIS model using the dielectric characteristics and dissolved gases as input. The results show that the correlation between the DP pred decreasing rate (DP dec_rate ) and the loading factor is more significant than that between the HI dec_rate and the loading factor