A quasi-three-dimensional field mathematical model of the electromagnetic field and heat transfer processes in end zone of a powerful turbogenerator has been developed. A model is the intermediate version between two-dimensional and three-dimensional solutions and is based on the numeral calculations in transversal and longitudinal sections of turbogenerator, interconnected by a complex of boundary conditions. On the first stage, a two-dimensional field model of the electromagnetic field in transversal section of central zone of a turbogenerator is considered. Then, taking into account the field distribution in central part, the magnetic field in longitudinal section is simulated. In response to the symmetry of the machine along axial and radial directions, the calculation area of end zone is considered as a half of the rotor section along its axis and the section of the stator core tooth in the tangential direction (circumferentially). Having taken the distribution of electromagnetic parameters obtained in the load mode of the machine as the initial data, the thermal losses in the elements and nodes of the end zone are determined. As a result of solving the joint problem of calculating the electromagnetic field and heat exchange processes, the distribution of heating has been obtained not only on the surface, but also inside the structural parts of the end zone. In particular, it has been found that the maximum temperature of 97.3 °C takes place in the tooth area of the end package of the stator core. This is explained by the combined effect of the main radial field, the axial leakage flux of the frontal portions of the stator and rotor windings, as well as by the “buckling” of a portion of the main flux out of the air gap. In addition, the pressure plate shielding effect is the cause of local field concentration in the toothed zone of the end package. The presented model makes it possible as early as at the design stage to evaluate the efficiency of design solutions for the formation of the end zone of the turbogenerator stator for different load modes of the machine, including the modes of consumption of reactive power.

With the aid of mathematical and physical simulation the electromagnetic field distributions in the end zone of a powerful turbogenerator has been obtained. On the basis of the comparison of the axial component of the magnetic induction on the surface of the extreme package of the stator core of the large-scale physical and mathematical models with the data of the field experiment, conclusions are drawn about the reliability of the results obtained. The data of the simulation and the field experiment correspond to the same turbogenerator, which makes it possible to evaluate the correctness of the construction of the mathematical model. It is shown that physical modeling makes it possible to evaluate the regularities of the distribution of the electromagnetic field (without obtaining accurate quantitative indicators) and can be used for qualitative comparison of the effectiveness of various design solutions of the end zone of the stator. However, such models have not become widely used, since numerous studies are required to form meaningful and sufficiently detailed conclusions about the parameters and characteristics of the object, the design of the end zone of high-power generators is complex, and the calculation of three-dimensional models is time-consuming and even with modern computer technology is associated with a number of simplifying factors. In mathematical modeling, a sequential logical transition is applied from a simple model of the central part of the machine to a more complex model of the end zone using preliminary results, which makes it possible to obtain data on the distribution of the electromagnetic field in complex areas. With the help of specialized software, a model has been created that is quite flexible in terms of modifying individual components, characterized by accessibility, visibility and unlimited possibilities for experimentation, including predicting situations that have not previously occurred or can give unpredictable results.

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The troubleproof and efficient work of powerful turbogenerators depends on the stability of their main mechanical parameters, which include the stator core pressing. The aim of the work was to describe the possibility of using a multielement capacitive sensor with coplanar electrodes to measure the movement of disk springs of the stabilizer systems power batteries in the turbogenerator stator core.The state of the core pressurizer can be indirectly assessed by measuring the displacement of the disk springs in power accumulators, which are installed on the tightening prism of the core instead of the compression nuts. To measure the movement of springs, a coplanar capacitive sensor with sectoral electrodes built into the power accumulators design is proposed. Each sector contains its own elementary sensor formed by coplanar electrodes. Each elementary sensor in each sector is placed on an annular dielectric plate and is formed by coplanar electrodes that are part of coaxial concentric rings. The sensor consists of a high-potential, low-potential and grounded electrodes. A grounded electrode is located between the high-potential and low-potential electrodes, as well as around them.A simplified analytical calculation model for obtaining the analytical response characteristic of the change in the informative component of the sensor electric capacity on the course of the disk springs in the CA is presented. The reliability of the model and the response characteristics are confirmed experimentally by testing a laboratory prototype of a capacitive sensor.