Typical Gas Concentration Values and Typical Rate of Gas Increase on DGA Test in PLN UIT-JBT

Abstract

Since more than 15 years ago, PLN had been using DGA to determine the condition of power transformers whether it is experience arcing, thermal or corona. PLN UIT-JBT applying DGA every semester on 448 units of power transformers which have several rating voltages i.e. 500/150kV, 150/70kV, 150/20kV and 70/20kV. In order to understand what should PLN do to the power transformer based on DGA test, some standards are used as reference to do further action which are IEC 60599 and IEEE C57-104. IEC 60599 recommend any electricity utilities that had a huge number of DGA result to generate typical gas concentration values and typical rate of gas increase as an internal standard to decide which transformer are defined to be normal in operation or abnormal in operation so will be easier for utility to plan a further treatment to the transformers. This paper eventually will describe the comparison of typical normal boundaries of gas value on IEC, IEEE and PLN typical data. Typical rate of gas increase that been calculated can also be used as a reference to determine which power transformer had severe internal faults. Both typical gas concentration values and typical rate of gas increase using 90% of test data population as a range of normal operation, while the other 10% considered as abnormal operation. From the comparison among IEEE, IEC and PLN typical data it was known that the typical values for normal condition are almost at the same level, but only C2H2 gas where IEC value have the highest which is 20 ppm. In the end by creating a new reference to interpret DGA test result using our own data’s, which it is came from our system, whether it is on typical gas concentration values or typical rate of gas increase, we could have more confidence and higher accuracy to understand what is actually happened on our power transformers.