Five Years´ Experience with Transformer Total Combustible Gas Fault Detector Tests

Results of incipient fault tests of several thousand power transformers are described. The tests were made with the first practical method and a new instrument for measuring total combustible gas (TCG) in the gas space above the oil in transformers. Useful up-to-date information is presented on instrument sensitivity and calibration, effect of gas contaminants, reading reproducibility, sampling methods, classification and interpretation of TCG readinigs, and comparison of the TCG method with separate analysis of gas components. A tabular report of a field survey of TCG tests on transformers is made. A comprehensive bibliography is given. Recent data on application of the method to vented or free-breathing transformers are also presented.