The paper presents results of the experiments conducted at/on a number of pump units with synchronous electric engines which are used at group pump stations in the process of oil production. Purpose of the experiments is to determine actual possibilities of group pump station units while using them as regulating loads of active and reactive energy. The experimental results have made it possible to construct power and economic characteristics. Taking into account these characteristics a method of load distribution for each unit at specified total load is proposed in the paper.

The paper contains processing results of digital current and voltage oscillograms as effective, mean and peak volt-ampere characteristics of a serviceable current transformer with short- circuited turns. Digital current and voltage oscillograms and curves of volt-ampere characteristics permit to detect presence or absence of short-circuited turns in secondary windings of current transformers.

Two-dimensional temperature field model is proposed to calculate flat contact heating. Numerical algorithms for calculation of contact temperature have been developed on the basis of finite-difference method. The paper reveals temperature distribution in cross-section of flat and knife-blade contacts at various time moments in the regime of short circuit. The investigations have shown that the contacts with protective coatings characterized by poor conductance in the regime of short circuit have significant local overheatings along contact edges.

The paper proposes correction method of a design diacoptic Z-matrix of complicated power system that ensures high manoeuvrability while calculating steady - state conditions.

An analytical method for solution of multidimensional problems of heat conductivity with phase transformations which is based on integral equation method has been developed. The method makes it possible to determine interfacial boundary motion law excluding determination of temperature field and it also permits to investigate stability of its shape. The paper reveals that the proposed method is rather efficient in the case when heat transfer takes place in one phase.

The paper proposes utilization of discharged heat of gas-piston engine (GPE) or contact steam-gas plants (SGP) with the purpose to heat up gas at gas-distribution stations (GDS) of combined power plants with turbine and gas-expansion units. Calculations prove significant economic efficiency of the proposed variant in comparison with the application of ordinary gas- turbine units. Technical and economic calculation is used to determine gas-piston engine or contact steam-gas plant power for specific operational conditions of gas-distribution stations and utilization rate of discharged heat.

The solution of a differential heat conduction equation is given in view of cooling effect of moisture evaporation from a heated surface. In this case heating heat flow is diminishing in time exponentially. The most typical nomographic temperature and temperature gradient charts of heated surface and mean temperature of a plate are presented in the paper.

Application of a «heat wave» method which is used to diagnose condition of thermal insulation and evaluate heat losses in heat pipe-lines of centralized heat supply systems is given in the paper. The paper contains mathematical calculations which make it possible to develop mathematically the method which is applied to process experimental data obtained during operation of heat-supply system.

The paper considers one of the approaches to rehabilitation of radionuclide contaminated territories of the Republic of Belarus. In accordance with the proposed method it is possible to produce ecologically clean product on the lands affected by the Chernobyl accident that is electric power with application of renewable energy sources such as solar energy, wind and biomass.

The paper considers a mathematical model of pulsation of gas explosion products in the operational chamber during gas-impulse regeneration of water well filters. Second-order differential equation with constant coefficients has been derived. A special calculation program has been developed to solve the equation. The paper proposes analytical method for determination of maximum hydraulic flow rate. In order to increase efficiency of regeneration improved technological treatment schemes are given in the paper.