In aerial transmission lines aluminium multiwire conductors are in use. Owing to their flexible design the electrodynamic effect of short circuit currents may lead to intolerable mutual rendezvous and even cross-whipping of the phase conductors. The increasing motion of the conductors caused by effect of the short-circuit electrodynamic force impulse is accompanied by the dynamic load impact affecting the conductors, insulating and supporting constructions of the aerial lines. Intensity of the short-circuit currents electrodynamic impact on the flexible conductors depends on the short circuit current magnitude. For research into electrodynamic endurance of the conductors of the aerial lines located at the vertices of arbitrary triangle with spans of a large length, the authors assume the conductor analytical model in the form of a flexible tensile thread whose mass is distributed evenly lengthwise the conductor. With this analytical model, by the action of the imposed forces the conductor assumes the form conditioned by the diagram of applied external forces, and resists neither bending nor torsion. The initial conditions calculation task reduces to solving the flexible thread statics equations. The law of motion of the conductor marginal points comes out of the conjoint solution of dynamic equations of the conductor and structural components of the areal electric power lines. Based on the proposed algorithm, the researchers of the Chair of the Electric Power Stations of BNTU developed a software program LINEDYS+, which in its characteristics yields to no foreign analogs, e. g. SAMSEF. To calculate the initial conditions they modified a software program computing the flexible conductor mechanics named MR 21. The conductor short-circuit electrodynamic interaction estimation considers structural elements of the areal lines, ice and wind loads, objective parameters of the short circuit. The software programs are accommodated with the simple and intelligible user interface and can produce automatic reports. For the computation certainty valuation of the developed software program, comparison of the experimental and design values was performed on an engineering prototype span of the French state-owned company Electricite de France. 

The article considers experimental and analytical determination of the asynchronous machine equivalent-circuit parameters with application of the reference data. Transient processes investigation of the asynchronous machines necessitates the equivalent circuit parameters (resistance impedance, inductances and coefficient of the stator-rotor contours mutual inductance) that help form the transitory-process mathematical simulation model. The reference books do not provide those parameters; they instead give the rated ones (active power, voltage, slide, coefficient of performance and capacity coefficient) as well as the ratio of starting and nominal currents and torques. The noted studies on the asynchronous machine equivalent-circuits parametrization fail to solve the problems ad finem or solve them with admissions. The paper presents experimental and analytical determinations of the asynchronous machine equivalent-circuit parameters: the experimental one based on the results of two measurements and the analytical one where the problem boils down to solving a system of nonlineal algebraic equations. The authors investigate the equivalent asynchronous machine input-resistance properties and adduce the dependence curvatures of the input-resistances on the slide. They present a symbolic model for analytical parameterization of the asynchronous machine equivalent-circuit that represents a system of nonlineal equations and requires one of the rotor-parameters arbitrary assignment. The article demonstrates that for the asynchronous machine equivalent-circuit experimental parameterization the measures are to be conducted of the stator-circuit voltage, current and active power with two different slides and arbitrary assignment of one of the rotor parameters. The paper substantiates the fact that additional measurement does not discard the rotor-parameter choice arbitrariness. The authors establish that in motoring mode there is a critical slide by which the stator current value turns out to be the minimum. 

Large quantity of asynchronous motors work in heavily dusted environments. On the end-winding insulation of the motors to 55 kW operating in the mining and smelting enterprise there is a 3 cm dust layer, which may lead to the asynchronous motor end-winding local overheat and consequent early breakdown. Contemporary literature allocates insufficient consideration to the issue of studying the impact the winding dust pollution has on the motor lifespan; for the most part they are experimental researches. The article investigates and establishes correlation relationship between the additional winding heating and the end-winding dust layer thickness. The investigation considers the induction motor winding to be a homogeneous solid and assumes the motor thermal conditions steady inasmuch as the winding insulation dust-cover forming time is much greater than the motor-heating time constant. The obtained expression permits determining the winding dust level by temperature variations; the dependence has linear character. Neither the motor type, size, nor the capacity do affect the local insulation overheating since the temperature difference between the windings being dust laden does not exceed 10 % for asynchronous motors of various capacity. The authors develop an appliance that enables the winding dustiness level monitoring and signals of necessity for the preventive cleaning measures implementation. The appliance operation principle is based on measuring results comparison of the two temperature-sensing devices mounted on the end-winding: one – in the upper part, and the other – in the bottom. The differential in the sensors reading-out allows estimating the dust layer sedimentation on the end-winding. A patent of invention has been issued on the investigation results. 

The paper ascertains and presents alteration in the energy consumption as a consequence of utilizing the low-temperature waste streams commonly used in the lines of continuous dyeing at the finishing shops of textile enterprises of Belarus. The utilization realizes through the engagement of lithium-bromide absorption heat pumps with various energy characteristics such as the heating coefficient (relative conversion ratio COPhp = 1,15; 1,7; 2,2) and the heating capacity. The latter associates with the converted heat-flow energy utilization variant with the heat-transfer medium heating system scheme (one-, twoand multistage heating). The article considers transition to previously not applied service-water preheating due to the technological acceptance of feeding higher temperature water into the dyeing machine and widening specification of the heattransfer media. The authors adduce variants of internal and external energy use and their evaluation based on the relative energy and exergy characteristics. With results of the thermodynamic analysis of the modernized production effectiveness the researchers prove that alongside with traditional and apparent interior utilization of the energy associated with the stream heat recuperation, it is advisable to widen the range of applied heat-transfer media. The transition to the service water twoand multi-stage preheating is feasible. The study shows that the existing energy supply efficiency extremely low index-numbers improve by one or two degrees. Since they are conditioned, inter alia, by the machinery design, traditional approach to energy supply and heat-medium usage as well as the enterprise whole heating system answering requirements of the bygone era of cheap energy resources. The authors examine the continuous dyeing line modernization options intending considerable investments. Preliminary economic assessment of such inevitable modernization options for the enterprise entire heat-and-power system shows reality of meeting all going with the times requirements such as economic, environmental, energy for similar projects. 

The article considers effectiveness increase of the TPP heat-mechanical equipment repair, manufacturing and maintenance as exemplified by gas-thermal technique for hardening laststages rotor blades of the steam turbines. The rotor blades work under conditions of intense power loading, their airfoil being erosion-corrosion destructed by the action of the moist-steam flow. Repairing companies employ quite a number of technologies to restore some of erosion-worn rotor blades. Inter alia, argon-arc, plasma and gas-powder weld deposition of the original material with subsequent machining, stellite protection recovery, electrical spark alloying the entry edge mat surface, spraying ion-plasma coating on the blade airfoil surface. In domestic turbine building, rotor blades of the steam turbines last stages are manufactured of martensitic class stainless steel. The key condition for successful blade restoration is thermal effect minimizing on the base material for excluding the slag areas possible forming. The laser surface coating technology provides these conditions. They coat the surface of an item being processed by way of melting the base and the adding material. In as much the base melts smallest, the coating characteristics depend mainly on the properties of adding material. The procedure of laser coating passes through several stages including physical contact creation, chemical interaction (laser radiation absorption), volumetrical processes resulting in formation of stable bonds in volume of the materials that have reacted. For the low-pressure cylinder rotor blades supplementary protection against erosion destruction, LLC ‘Technological Systems of Protective Coating’ developed technology of the blade airfoil protective finish by method of high-speed gas-flame sputter. The company realized this technology in 2012 during K-200-12,8 turbine (of the Leningrad Metallurgical Works – LMZ) repairing in Zainsk SDPP by JSC ‘Tatenergo’. The feature of the technology is performing the rotor blade airfoil surface hardening without extracting the rotor out of the low-pressure cylinder and with rotor blades remaining on the rotor. According the SDPP data, as for the beginning of 2015 there are no traces of the rotor blade erosive wear detected. 

The three-element system for automatic water-level regulation in the boiler shell as well as its modifications received maximal dissimilation in the Republic of Belarus and the CIS countries power economies. Though, they possess the following shortages: occurrence of the steadystate errors at the end of the transient process during the control response to internal disturbances and those by over-heated steam; large level deviations at sharp and significant load changes, which often leads to the boiler or the power block deloading or stoppage. As a remedial action against the mentioned disadvantages, the invariant systems for the drum boiler automatic feed regulation were developed earlier. The first variant of the automatic regulation invariant system with the equivalent external disturbance individualization differs from the typical one in the way that they select the stabilizing controller arrangement on the basis of transmission response of the optimal controller. And the compensating device dynamic settings structure and parameters are chosen with respect to the equivalent controlled member including the stabilizing controller inner contour. The second variant offers the compensating device transmission response to the equivalent external disturbance represented as series-connected typical sections: a real differentiator and a quick-response unit. For the control action maximum value reducing in this scheme, there is a suppressing device additionally installed at the exit of the equivalent external disturbance compensation device. The automatic regulation invariant systems eliminate steady-state errors at all impacts and allow improving significantly the level control quality at variable conditions. For economic efficiency evaluation of the boiler-shell water level automatic regulation innovative system implementation as a system, the author proposes a technique allowing calculating the main components of the economic effect of its implementation. Inter alia, increasing reliability (faultlessness) of the boiler operation, increment in the boiler efficiency at the expense of essential action-execution time decrease as compared with the typical automatic regulation system and longevity of its operation. 

Increasing the solid lighting facilities operational energy-efficiency in the national economy of the Republic of Belarus is of current concern. The modern problems of energy-saving lighting are multifaceted and broad-ranging. It is particularly burning amidst the energy crisis and the world commercial slump. Thus, the lighting demands 10–13 % of the total electric energy consumption in Belarus. That is to say, there is a significant potential of energy saving in transition to energy-efficient lighting. The paper considers the issues of reliability and service period of the solid-state lighting devices created on the basis of lines of light-emitting-diodes (LED) produced by Paragon Semiconductor Lighting Technology Co., Ltd. The optoelectronic apparatuses reliability assessment is based on investigation of the development principles and deterioration mechanisms leading to failures of one kind or another. The deterioration causes ascertainment is indispensable for acting upon them later on and thus reducing the degradation speed and extent. One of the LED-devices deterioration main sources is the temperature overheat of the LED-chip active area. Therefore, techniques for evaluating the heat characteristics of solid lighting devices become the issue of the day. The article investigates thermal properties of high-capacity blue LED-lines by method of electrical transient processes. The authors calculate temperatures in the LED-lines active areas at various heat-dissipation conditions and injection currents values. They realize computer generated simulation of the heated lines thermal fields applying the ANSYS packet. The study concludes that out of the degree of temperature-distribution heterogeneity along the line impossibility of the line chip structural units thermal characteristics extraction arises based on all LEDs homogenized over the line temperature-time dependences. The paper indicates that one can with reasonable accuracy obtain the LED-lines thermal parameters employing the line representation with two equivalent RC-strings corresponding the thermal ways ‘LED active area – aluminium base’ and ‘aluminium base – environment’. For these areas thermal time constants, thermal resistances and thermal capacities are determined. 

Technologies of direct conversion of the fuel energy into electrical power are an upcoming trend in power economy. Over the last decades a number of countries have created industrial prototypes of power plants on fuel elements (cells), while fuel cells themselves became a commercial product on the world energy market. High electrical efficiency of the fuel cells allows predictting their further spread as part of hybrid installations jointly with gas and steam turbines which specifically enables achieving the electrical efficiency greater than 70 %. Nevertheless, investigations in the area of increasing efficiency and reliability of the fuel cells continue. Inter alia, research into the effects of oxidizing reaction thermodynamic parameters, fuel composition and oxidation reaction products on effectiveness of the solid oxide fuel cells (SOFC) is of specific scientific interest. The article presents a concise analysis of the fuel type effects on the SOFC efficiency. Based on the open publications experimental data and the data of numerical model studies, the authors adduce results of the statistical analysis of the SOFC thermodynamic parameters effect on the effectiveness of its functioning as well as of the reciprocative factors of these parameters and gas composition at the inlet and at the outlet of the cell. The presented diagrams reflect dimension of the indicated parameters on the SOFC operation effectiveness. The significance levels of the above listed factors are ascertained. Statistical analysis of the effects of the SOFC functionning process thermodynamical, consumption and concentration parameters demonstrates quintessential influence of the reciprocative factors (temperature – flow-rate and pressure – flow-rate) and the nitrogen N₂ and oxygen O₂ concentrations on the operation efficiency in the researched range of its functioning. These are the parameters to be considered on a first-priority basis while developing mathematical models for optimizing the solid oxide fuel cells operating modes.