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Vol. 21 (2018 year), No. 4, DOI: 10.21443/1560-9278-2018-21-4

Popov I. P.
Influence of frequency on the synchronous electrical machine parameters

The current and moment of resistance to rotation of the inductive synchronous electric machine under inductive load have been considered. For a synchronous machine with an inductive load, Theorem 1 is valid: the current amplitude in the inductive load of an inductive synchronous electric machine is independent of the rotational speed. The theorem has been proved by equating the second Kirchhoff law and the law of electromagnetic induction with reference to a rotating machine. Theorem 2 is also valid: the moment of resistance to rotation for an inductive synchronous electric machine with an inductive load is independent of the rotational speed. The theorem has been proved by analyzing the Ampere law with respect to a rotating machine. It has been established, with active load, the current amplitude and the moment of resistance to rotation depend linearly on the rotational speed. However, with capacitive load, these parameters are quadratically dependent on the rotational speed. The connection of power with frequency under various types of machine load has been proven: for inductive load, the reactive electric power is linearly dependent on frequency; for resistive load, the dependence is quadratic; at the same time, for capacitive load, the power is cubic dependent on frequency. For a synchronous capacitive machine with capacitive load, Theorem 3 and 4 are considered to be valid. Theorem 3: the voltage amplitude on capacitive load of a capacitive synchronous electric machine does not depend on the rotational speed. Theorem 4: the amplitude of the resistance to rotation moment for a capacitive synchronous electric machine with capacitive load does not depend on the rotational speed. The results are recommended to use when designing electrical systems.

(in Russian, стр.6, fig. 1, tables. 0, ref 10, adobePDF, adobePDF 0 Kb)

Vol. 22 (2019 year), No. 4, DOI: 10.21443/1560-9278-2019-22-4

Popov I. P.
Methods for determining the scattering of transformer windings individually

The total leakage reactance of the transformer with concentric cylindrical windings depends on the thickness of the coils and the gap between them. Existing methods do not allow measuring reactance of scattering for each winding of a transformer separately, therefore, for simplicity they are often considered equal to each other. In fact, in relation to the case under consideration, they are essentially not equal. In fact, the calculation of the flux linkage of the external winding shows that its reactive scattering resistance is greater than the total scattering resistance of both windings. Two circumstances follow from this. First, the internal winding of the transformer absorbs magnetic flux to a greater extent than it scatters (scatters its magnetic flux, absorbs from the external winding). The second is that its (equivalent) scattering reactance is capacitive. The purpose of the study is to justify the possibility of experimental determination of the scattering reactance for each transformer winding separately. The relevance of the work is due to the widespread distribution of transformers. The dissipation reactance of each winding of the transformer individually can be determined by at least three experimental methods that give satisfactory agreement between the results. An almost paradoxical result is the capacitive nature of the scattering resistance of the inner winding of the transformer obtained only for concentric cylindrical windings. It should not be generalized to other types of windings. The presented experimental methods are not tied to the nature of the reactivity of scattering resistances. They are universal and can be used with any type of windings. The results obtained are recommended for use in the design and study of transformers.

(in Russian, стр.8, fig. 2, tables. 0, ref 10, AdobePDF, AdobePDF 0 Kb)