ENERGY SYSTEMS AND ELECTRICAL NETWORKS AN ESTIMATE OF THE LIMIT STATE OF POWER TRANSFORMERS AND AUTOTRANSFORMERS

The main indicators of the limit technical state of transformers and autotransformers, for which their further use is impermissible or inadvisable, are considered. The main elements of a power transformer which determine its limit state are the windings and the cores. Important indicators for estimating the technical state of the windings is the wear of the coil insulation, the degree of mechanical fastening of the windings and, in particular, the absence of dangerous deformations. Wear of the coil insulation is estimated from the degree of polymerization and the short-circuit resistance. The cores of the transformer become damaged fairly rapidly during operation. Normalized values of the above indicators are given as well as experience in using them in the Russian Federation and the Ukraine to estimate the limit state of transformers and autotransformers. The amount of inspection in order to reach conclusions on the technical state of a transformer and temporary measures until they are replaced are indicated.