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A comparative analysis of the characteristics of foreign and domestic generator circuit breakers is carried out. The necessity of developing a domestic generator circuit breaker for newly constructed nuclear power plants with a power unit capacity of over 1200 MW is shown. The most promising solution is the development of hybrid generator circuit breakers using main contacts, vacuum circuit breakers and controlled arresters. The scheme and operation of elements of hybrid circuit breakers in modes of shutdown of three phase short circuit current is resulted. The developed mathematical model of hybrid breakers consisting of generator, busbar and transformer for power plant and given transients disable the short circuit current in different modes. It is proposed to develop hybrid circuit breakers to replace oil and air circuit breakers at the stages of modernization of nuclear power plants, and in the new construction it is advisable to use generator circuit breakers, as a prototype of which the gas-insulated device developed by ABB is given. Basic electrical formulas for estimation of the switching capacity of the circuit breaker of the generator in the amplitude of the current gap three phase short circuit current, degree of asymmetry, amplitude and rate of rise of transient recovery voltage formulated.

The article considers the relation between the new technologies of components and the level of AC and DC equipment sets. It is pointed out that switching and protection apparatuses and semiconductor devices are the key components for development of low- and medium-voltage electrical equipment sets. The data and characteristics of switching and protection apparatuses made on the basis of vacuum and SF6 circuit breakers are presented. The advantages of constructing hybrid low- and medium-voltage devices by using a combination of vacuum circuit breakers, controlled surge arresters, and overvoltage suppressors that can be used in multi-substation DC cable networks (MDCN) are pointed out. The domestically produced light-activated thyristors, thyristors, and IGBT modules may serve as a basis for constructing low- and medium-voltage cable MDCNs.

We investigated the long-term impact of the largest Russian cement plant on mesopodzol sandy soils and Scots pine stands. We determined the distributions of the total and available pools of Ca, Mg, K, Na, Mn, Fe, Zn, Ni, Cu, Pb and Cd in the soil profile to a depth of 60 cm (illuvial horizon) as well as the accumulation patterns of these elements in the vegetative and generative organs of Scots pine trees. High Ca accumulation in the impact zone soils was a result of CaO emissions by a cement plant. Also, CaO became the main cause of soil profile alkalization due to neutralization of soil acids and formation of calcium hydroxide or carbonates. Alkalization immobilized substantial amounts of Fe, Mn, Zn and Ni in the soil, reducing their availability. The most prominent effect of long-term cement production was a prominent Mn deficiency in vegetative and generative Scots pine organs due to the exhaustion of the available Mn pool in the illuvial horizon. The miniaturization of cones, a decrease in seed yield and a reduction in seed germinability were observed in the emission impact zones. Pretreatment of Mn-deficient seeds with manganese eliminated Mn deficiency but did not increase seed germination.