Diagnostic techniques and apparatus for detecting faults in perfluorocarbon liquid immersed transformers

This paper deals with techniques and an apparatus designed to diagnosis transformer faults by detecting C/sub 2/F/sub 4/, C/sub 2/F/sub 6/ and C/sub 3/F/sub 6/ gases contained in perfluorocarbon (PFC) liquid. The authors first established fault diagnostic techniques that employ gas patterns, gas composition ratios and fault diagnostic diagram and flow chart, based on the C/sub 2/F/sub 4/, C/sub 2/F/sub 6/ and C/sub 3/F/sub 6/ gases generated by overheating, partial discharges and arc discharges. Then, the authors verified the possibility of diagnosing internal faults in PFC liquid-immersed transformers when internal fault simulation tests on transformer model are conducted. The C/sub 2/F/sub 4/ and C/sub 3/F/sub 6/ gases generated there are detected with the gas diagnostic apparatus equipped with a gas sensor.