초록 ▼

A gas chromatograph measures the gas concentration levels of fault gases contained in the gas within a headspace above the electrical insulating oil supply contained in a power transformer. An on-line fault detection system involves gas samples taken from transformers at a utility site in sequence w

A gas chromatograph measures the gas concentration levels of fault gases contained in the gas within a headspace above the electrical insulating oil supply contained in a power transformer. An on-line fault detection system involves gas samples taken from transformers at a utility site in sequence with automatically controlled timer valves which open to draw a gas sample from each transformer headspace and then transfer the gas directly to a single gas chromatograph. The gas chromatograph includes an integrator which calculates the concentration level of each fault gas in the gas sample. The resulting fault gas data are fed to a computer programmed with a partition function based on Henry\s Law to convert the headspace fault gas data to fault gas concentration levels within the transformer oil. This produces gas fault analysis data which are used to provide an early warning of specific transformer problems correlated to, indicative of and detected by excessive dissolved fault gas concentration levels in the oil identified with particular transformer faults. The invention avoids costly and time consuming prior art analysis techniques of extracting fault gases from the oil sample in an independent operation before the concentration levels can be measured.

대표청구항 ▼

A method for monitoring dissolved gases in the electrical insulating oil supply of an electrical transformer in which a blanket of ambient gas containing a plurality of fault gases is present in an equilibrium state in the headspace above the insulating oil supply contained in the transformer, the m

A method for monitoring dissolved gases in the electrical insulating oil supply of an electrical transformer in which a blanket of ambient gas containing a plurality of fault gases is present in an equilibrium state in the headspace above the insulating oil supply contained in the transformer, the method comprising: withdrawing from the headspace a sample of the ambient gas present in the headspace and transferring the withdrawn gas sample to an instrument for measuring the amounts of particular fault gases present in the gas sample; operating said instrument for measuring the gas concentration levels of the fault gases contained in the gas sample; applying fault gas measurement values determined by said instrument as an input to a programmed computing device informed of a gas temperature and pressure dependent gas partition function between the headspace gas and the oil-dissolved fault gases based on gas solubility and gas/liquid equilibrium constraints according to Henry\s Law; determining the temperature and pressure of the ambient gas within the headspace, informing the programmed computer of said gas temperature and pressure information so that gas temperature and pressure corrections can be made according to the ideal gas law for the ambient gas within said headspace, and using said gas temperature and pressure information as an input to the gas partition function; calculating the related gas concentration levels of said fault gases which are present in the transformer oil supply by operating the computing device in relation to said partition function to convert fault gas concentration levels in the headspace to related measurements of the concentration level of particular fault gases in the transformer oil supply; and thereafter producing a reading of the calculated fault gas concentration in the transformer oil supply to provide an indication of a specific transformer fault.