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ANALYSIS THE REASONS OF 110 kV TRANSFORMERS BREAK DOWN AND THE METHODS OF ITS DIAGNOSTICS

The article deals with the diagnostics of power transformers by different methods. Particular attention is paid to modern methods and diagnostic tools that maximally allow to determine the state of the transformer. Based on the statistical processing of the results of the research, the authors indicate that the most common failures are: damage to the windings of transformers with the possibility of regulation under load, without disconnecting power and leaving consumers without power supply (RPN) for any period of operation. The greatest number of damages for transformers with on-load tap-changers with a service life of 10-30 years, for high-voltage bushings after 10 years of operation. The most severe damage to the transformer is an internal short circuit (short circuit). These types of overvoltage cause damage to the windings in 80% of the total number of damage, high-voltage bushings - 89%, RPN - 25% and other elements - 36%. It is indicated that a serious consequence occurs when such defects develop, as: the reduction of the electrical strength of the oil channel of high-voltage hermetic bushings due to deposition of sediment on the inner surface of porcelain and on the surface of internal insulation; reduction of the electrical strength of paper-oil insulation of high-voltage leaky inlets due to moisture and pollution; humidification, contamination and wear (aging) of the insulation of the windings; burn-out of the coil insulation and windings of the windings because of the long non-operation of the through-current fault on the low-voltage side of the transformer; errors in installation, repair and operation. In the conclusions it is recommended to supply the manufacturers of power transformers with means for diagnosing the main elements of power transformers, which should be built-in. Particular mention was made of the need to focus in the future on improving existing and creating new methods for monitoring equipment of power transformers.