Перегляд за Автор "Kostiukov, Ivan Aleksandrovich"
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Документ Dielectric dissipation factor in three-core power cables(Видавництво Національного університету "Львівська політехніка", 2021) Kostiukov, Ivan AleksandrovichThis article is devoted to the analysis of components of variance of the results of measurements of dielectric dissipation factor of insulation layers between the conductive elements of the construction of three core power cables with paper impregnated insulation in a common sheath. The analysis of components of variance was carried out by applying presented relations for the direct calculation of the dielectric dissipation factor. The accuracy of presented relations for the calculation of variance components was verified. The results of carried out analysis have shown that the variance of the dielectric dissipation factor measurements is mostly determined by the variances of multiplication of measurements of aggregate values of dielectric dissipation factor and coefficients depending on the partial capacitances of tested three core cable.Документ Electrical capacitance measurement by scatter ellipse approximation(Видавництво Національного університету "Львівська політехніка", 2020) Kostiukov, Ivan AleksandrovichThis article is devoted to the substantiation of the possibility of electrical capacitance measurement utilizing equations that are based on the approximation of scattering ellipse, formed by signals proportional to the current flowing through the capacitive tested object and voltage drop on the tested object. On the contrary, to previously developed algorithms, which were based on the approximation of the scattering ellipse by applying the least-squares method, in this case, the approximation was carried out by simply using the values of signals amplitude directly determined from current and voltage curves. The value of the phase shift between the current and voltage curves, which is also necessary to approximate the shape of the scattering ellipse, was determined by using the cross-correlation method. Besides, the article provides formulas for calculating the reactive component of voltage drop on the tested object which is based on the approximation of scattering ellipse without using the least-squares method. Formulas for calculation of the reactive component of the voltage drop on the tested object after the reduction of the quadratic form of the elliptic curve to its canonical form are also given. The results of the impact of the reduction of the quadratic form of scattering ellipse to its canonical form on the value of correlation coefficient between sine curves of current and voltage as well as on the magnitude of major semi-axis and minor semi-axis of scattering ellipse are illustrated. Also, it was shown the relationship between the values of the reactive component of voltage drop on the capacitive tested object, which were determined before the reducing of the quadratic form of scattering ellipse to its canonical form and after such reducing. Despite the rejection of the applying of the least-squares method, to simplify the calculation algorithms, and also despite the presence of a significant noise component in sampled and processed curves of current and voltage, the experimental test has shown the sufficient level of accuracy and, consequently, the possibility of measuring the electric capacitance by approximating the scatter ellipse employing parameters of the quadratic form directly calculated from previously sampled sine curves of current and voltage.Документ The influence of stray inductance of tested object on technical performance of electrical capacitance meters with phase detectors(Національний технічний університет "Харківський політехнічний інститут", 2019) Kostiukov, Ivan AleksandrovichControl of technical state of electrical insulation by means of applying of electrical capacitance and power loss factor as informative parameters is complicated by the presence of stray parameters of tested capacitive object. The influence of stray inductance of tested objecton technical performance of measurement scheme based on applying of phase detector and voltage to current converter is considered in this paper. It was shown that the presence of inevitable stray inductance of tested object causes changes of active and reactive components of voltage on the output of phase sensitive detector. According to the results of carried out analysis, stray inductance canalso lead to the existence of substantial frequency dependence of electrical capacitance of tested object even in case of applying non-polar dielectric materials and to the distorted values of power loss factor of tested dielectric material. Finally, it was shown that the presence of stray inductance causes difficulties in estimation of technical state of electrical insulation due to substantial discrepancy between the value of effective capacitance, which has been measured under the influence of stray inductance, and the exact value of capacitance which implies negligible stray inductance. Considered in this paper deleterious influence of stray inductance and resonant phenomena on accuracy of carried out appraisal of technical state of tested capacitive object should betaken into consideration in case of applying measurement schemes with phase detectors.