The main reasons for the light gas protection of transformers in operation are as follows:
(1) There is a slight fault inside the transformer, such as short circuit between turns, local heating of the iron core, heating of the oil and the wall of the transformer tank caused by magnetism, etc., which produces a small amount of gas.
(2) Air invades the inside of the transformer.
(3) Long-term oil leakage or oil seepage causes the oil level to be too low.
(4) The welding of the transformer winding joints is not firm, and the contact resistance is too large, causing heating.
(5) Two-point grounding occurs in the secondary circuit, resulting in erroneous signals, etc.
After the light gas protection is activated, the on-duty personnel should immediately check the appearance of the transformer. For example: whether the oil level and oil color are normal; whether there is gas in the gas relay, the amount of gas and its color; check whether there is oil leakage in the transformer body and cooling system; whether there are abnormalities in the transformer load, temperature and sound. After external inspection, if no abnormality is found, the gas of the transformer should be sucked, and the nature of the gas should be verified by the laboratory personnel. If necessary, oil samples should be taken for gas chromatography analysis to comprehensively determine the type of fault.
