Typical Concentration Value and Typical Fault Type Based on DGA Test of Power Transformers in PLN TJBT

摘要

PLN have already implemented DGA for decades as a method to assess the condition of power transformers. PLN TJBT conducts DGA test annually on 448 units of transformers which consist of 500/150 kV, 150/70 kV, 150/20 kV and 70/20 kV voltages rate power transformers. To make an action based on DGA result, PLN use several references such as IEC 60599 and IEEE C57-104. IEC 60599 propose utilities to generate typical concentration values as a reference to determine which transformer are considered to be normal operated and abnormal operated in order to make a further action to the transformers. By using DGA test result of 448 power transformers in PLN TJBT, typical normal concentration values on each gas can be determined and compared with IEEE and IEC typical concentration values. The maximum concentration value between IEEE C57.104-2008, IEC 60599:2015 and PLN TJBT’s data on every gas almost showing the same level, except C2H2 gas where IEC 60599 have the highest value which is 20 ppm. PLN also use several methods i.e. ratios, key gases, Duval triangle and Duval pentagon to interpret DGA test result in order to know the fault type. This paper shows typical fault type among 448 units of power transformers in PLN TJBT including stray gassing possibilities.