Effects of lifetime and loading factor on dissolved gases in power transformers

Abstract

This Transformer experiences aging everyday as it gets older. The aging of transformer can be detected by assessing the condition of its oil insulation. Every transformer has its own aging rate which is influenced by many factors. This paper discusses about effects of lifetime and loading factor on DGA using regression linear method. 219 sample data including DGA and transformer age were collected from operating transformers in PT. PLN (persero). Specifically, the age of transformer ranges from 0 to 30 years and the rated voltage are 150/20kV and 150/70kV. The result shows that CO, CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , CO+CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and TDCG have strong correlations with transformer age. The strongest correlation is between CO and transformer age with correlation coefficient 0.715. Trend analysis of CO and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are carried out from transformer with various loading factors while the capacity and rated voltage are remained the same. The capacity of transformers discussed is 60MVA with rated voltage 150/20kV and 150/70kV. Loading factors of transformer ranges from 20 to 70%. Trend analysis shows that Transformer with higher loading factor will produce CO and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> more than transformer with lower loading factors. Higher loading factor in transformers will also cause CO and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> in its oil insulation increase faster.