Prus V. Aging of electric machines during long operation and repairs. Theory and practice.

The concept of aging of electric machines can be considered as partial loss of the properties and characteristics of the basic structural materials, elements and machines as a whole under the influence of the external factors arising in the course of operation and repairs. The dissertation paper relates to the solution of a topical research and applied problem of prolongation of term of effective operation of electric machines taking into account change of a condition of their structural units during long operation and repairs. For the first time the principles of aging of electric machines due to the current state of their structural units, which consist in a complex change of their parameters and characteristics, have been substantiated and systematized. The method for determining the components of instantaneous power, which differs in the systematization of different methods for determining and forms of representation of its components has been improved. For the first time a comprehensive approach to the design of systems for testing and certification of electrical machines during long-term operation and repairs has been substantiated. For the first time the complex nature of aging of laminated cores of electric machines during long operation and repairs has been substantiated. It consists in simultaneous change of properties caused by hysteresis, which characterize the state of the ferromagnetic material under local influence of eddy currents due to violation of interleaf insulation. Based on this, mathematical models for calculating electromagnetic fields in electric machines of various types and models for thermal calculation of windings of electric machines have been further developed. The method of calculation of electromagnetic and energy processes in electric circuits with steel has been further developed, which makes it possible to take into account the change of electromagnetic and energy parameters of electric machines with different degrees of aging. For the first time the systematic approach to development of models of definition and forecasting of reliability of electric machines with long mean time between failures has been substantiated and the structure, features of functioning and a set of rules for expert system which enables the assessment of the current technical condition of electric machines have been determined. The obtained scientific results have been confirmed by comparing the theoretical positions with the results of mathematical modeling and experimental research and implementation in production conditions.