Transient phenomena in power transformers theoretical and practical approach
In recent decades the theoretical and experimental study of transient phenomena regarding power transformers has experienced a great development. Results of these studies allowed the elucidation of the main theoretical and practical aspects of the transient phenomena due to propagation of impulse voltages inside the transformers. These studies increased the safe operation of power transformer and led to the introduction of rational insulation usage and also helped to develop efficient protection measures.
Calculation methods for lightning impulse voltage distribution in power transformers
This paper aims to develop and update the methodology for calculating the stress to which the internal insulation of power transformer is subjected during lightning impulse test. Power transformer internal isolation consists of insolating intervals of oil impregnated paper, transformer board and oil. In whole, the transformer's insulation must withstand the voltage testing levels prescribed by the standards. One of the methods for determining the internal stress of various parts of the power transformer's insulation is by using mathematical models.
Mathematical Simulation of Combustion of Boron Powder Gas Suspension
Based on a two-phase two-velocity model of a reacting gas-dispersed medium, a mathematical model of combustion of a boron powder gas suspension has been formulated. The results of numerical solution of the problem are presented. The influence of the composition of the gas suspension, its size, size distribution of particles, mass concentration of particles, as well as of the presence of aluminum powder in the suspension on the visible and normal velocities of flame propagation in the gas suspension, is shown. A comparison of the results of calculation with the well-known experimental and theoretical data is carried out. Satisfactory agreement of the predicted results with experimental data is shown.