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In phase coordinates, a mathematical model of a three-winding asynchronous machine with two windings on the stator as a structural element of electric drives and asynchronous generators with inverter and inverter-capacitor excitation for autonomous electric power plants, oriented to explicit methods of numerical integration of the system of differential equations, has been developed. The model takes into account the displacement angle between two stator windings in the range of 360º and other important factors affecting the course of electromagnetic processes occurring in the machine. On the basis of the mathematical model, a program code was developed as a means of computer verification of machine operation modes. The results of computer study performed with the help of the code confirm the suitability of the mathematical model of a three-winding asynchronous machine to take into account the influence of the displacement angle between the stator windings and their simultaneous and single power supply during the operation of the machine in motor mode. [ABSTRACT FROM AUTHOR]

A capacitive sensor for measuring the air gap between the boring of the stator core and the poles of the rotor in a powerful hydrogenerator is proposed and investigated. The sensor consists of a system of equal in width tape parallel coplanar high-potential and low-potential electrodes, between which grounded electrodes are placed. The ratios between the width of the high-potential, low-potential and grounded electrodes are selected depending on the size of the nominal gap. The electrodes are formed on a dielectric substrate mounted on the boring of the stator core. To reduce the effect of edge effects on the short sides of high-potential electrodes, the length of the low-potential electrodes is chosen to be smaller than the length of the high-potential electrodes by a value determined by the nominal gap. It is proposed to place all electrodes along the length perpendicular to the boring core generatrix to reduce the measurement error due to the influence of the rotor pole curvature. The electrical capacitance between the system of high-potential electrodes connected in parallel and the system of low-potential electrodes connected in parallel, which functionally depends on the size of the air gap, is measured. Analytical and graphical dependences for the sensor conversion function intended for use on a SGK538 / 160-70M bulb hydrogenerator have been determined. The value of the error caused by the curvature of the rotor poles in this hydrogen generator was calculated. The sensor in comparison with analogs has higher accuracy of measurement. The sensor or sensor system can be used as a standalone device or as part of monitoring and diagnostic systems. References 19, figures 6. [ABSTRACT FROM AUTHOR]

A comparative analysis of the characteristics of the salient pole synchronous machine for two variants of the rotor damping system design was performed by mathematical modeling methods. In the first embodiment, a traditional (internal) damping rotor system is used, which is made of electrically conductive rods immersed in the surface of the poles. In the second embodiment, the external damping system of the rotor is made in the form of conductive sheets fixed to the surface of the poles. It is noted that the external damping system of the rotor provides better asynchronous characteristics and is characterized by more uniform heating, which reduces the thermomechanical loads of structural elements. This design increases the reliability of the machine not only in the event of short-term asynchronous modes of operation, but also in the event of uneven air gap between the stator and rotor, which usually occurs during long operation of high-pole synchronous machines, such as hydro generators. [ABSTRACT FROM AUTHOR]

A device for automated control by the stator core of a powerful turbine generator (TG) during assembly and pressing at the manufacturing plant is proposed. Using the device, places in the core with a weakened solidity are determined. For this, at N points evenly spaced along the cross section of the stator core, the specific pressing pressure of special plastic elements, which are installed in the control cells of the additional pressure ring of the press, on which the core is assembled, is measured. During pressing, the elements are deformed, and their deformation depends on the degree of core defect (decrease in solidity) in the zone of which they are located. The sample will be deformed less, located in the zone of the largest defect, and most of all - in the zone where the defect is minimal. The pressure is measured using a flat metal membrane with a rigid center on which strain gauges are located at selected points. It is shown that the relative deformations in a flat membrane, which are measured by strain gages, depend on the value of the specific pressing pressure. Analytical relationships between the relative radial and tangential deformations and the specific pressing pressure have been determined [ABSTRACT FROM AUTHOR]

A block diagram of a laser measuring system with a fiber-optical sensor for monitoring the air gap between the rotor and stator of a hydrogenerator has been developed and analyzed. The system uses an algorithm for alternating comparison of the investigated and reference light fluxes. This makes it possible to reduce the influence on the measurement result of the gap of the instability of the parameters of individual units and blocks of such a system. The analysis of the main measurement errors, which can affect the result of determining the gap, is carried out. [ABSTRACT FROM AUTHOR]

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The method of calculating of the variable magnetic field is presented on the rotor surface of the synchronous machines. It is based on the multi-position numerical field calculations of the magnetic field in rotating of the rotor and the changing currents in the stator winding. This takes into account the real geometry of the electromagnetic system and the saturation of the magnetic core. A comparative calculation and harmonic analysis of the variable component of the magnetic induction are performed in the mode of the rated load for the two turbogenerators with a different amounts of teeth of the stator core. The proposed method is universal for different electric machines and modes of their excitation. [ABSTRACT FROM AUTHOR]

With respect to the magnetic stirrer of liquid metal in the mold continuous casting machines, made in the form of a synchronous motor with a hollow rotor and excitation system based on permanent magnets, the magnetic field is determined by the stator winding currents. We derive the boundary conditions for the magnetic potential on the surface of the molten metal produced by the stator currents, which are used for the numerical solution of the distribution of magnetic potential in the liquid metal ingot with an arbitrary distribution of its speed. A numerical-analytical method for the determination of the magnetic field in the structural parts of the mold, which is excited by currents of the stator winding. [ABSTRACT FROM AUTHOR]