Transformer diagnostics using dissolved gas analysis and polarisation and depolarisation current measurements — A case study

This paper presents analysis of the measurements carried out on three distribution substation transformers. Dissolved Gas Analysis (DGA) and Polarisation/Depolarization Current (PDC) measurements were carried out on three transformers. DGA analysis is carried out using Ratio methods and Duval's triangle. In addition, furan and moisture analysis are done from the oil samples. Then, PDC results of the same transformers are used to calculate paper/oil conductivity. Furthermore a discussion on the results of DGA and PDC measurements is presented.