Study on decomposition gas for faults diagnostic of electrical equipment using fluorocarbons

As the increasing demand for large capacity, high voltage and high reliability power transformers in urban power grid, oil-free, non-flammable and non-explosive equipment is recommended. For this reason, evaporative cooling transformers, gas insulated transformers and other electrical equipment using fluorocarbon as coolant and dielectric have been developed. This paper presents an experimental survey of the main components of decomposition products generated by several faults of electrical equipment using fluorocarbon; here evaporative cooling transformer and gas insulated transformer are taken as example. All experimental studies are carried out by simplified testing setups. The gaseous decomposition products formed during the tests are analyzed and assayed by means of GC/MS (gas chromatography/mass spectrometry) method. The amount of decomposition products varied with temperature, time and discharge capacity are studied. Based on these results, criterions for judging the fault type of this kind equipment is suggested, and it could be helpfulness to develop a diagnostic method for the new electrical equipment using fluorocarbon.