Том 89, № 5 (2018)

Operating-lock systems are intended to prevent emergencies and injury-causing hazards at power substations. To arrange operating locks in switch and control gear (SCG) cells, it is necessary to have technical tools of no-voltage and voltage detection on conductor buses. The use of no-contact capacitance voltage detectors is an efficient way to make the installation process less labor-intensive. A matter of substantial interest is the design of a no-contact device able to indicate the absence or supply of voltage in each separate conductor bus and initiate phase rotation. The designed voltage detector uses a system of three capacitance electric- field detectors installed in the SCG opposite to the respective lines. Each of the detectors is affected by the fields generated by all the lines when energized. Thus, the output signal of each detector is the sum of partial signals conditioned by the voltage of each separate phase. Each of the three partial components in such signals is detected by digital signal processing. The operation of the detectors under uncertainty was modeled by the Monte Carlo technique in the MATLAB environment. Each imitative test with a random set of parameters results in vector responses from the detectors. The test results help draw diagrams on a complex plane for full-phase and open-phase modes. It is shown that the pertinence of signal vectors to a specific region makes it possible to unambiguously identify the absence or supply of voltage for each separate conductor bus.

The use of rigid noncorona busbars with the air insulation, gas-filled current leads, and current leads with the polymeric insulation to connect various high-voltage elements at plants and substations allows providing a decrease in the electric energy losses, increase in reliability and safety of operation, as well as improving the ecological situation at the plants and substations. Compactness of the busbars is provided due to the use of new insulation media (first and foremost, electrically high-strength gases and polymeric dielectrics), as well as improvement of the technology of production and use of these materials. At present, various types of high-voltage current leads are used: shielded air busbars, busbars with the cast polymeric insulation, and sealed shielded current leads with the basic high-strength gas insulation. Engineering solutions in which insulation media with low dielectric permeability are used and the buses are made noncorona with rated operating voltage are applied to reduce the losses in the busbars.

One of the key factors determining the performance of a 110–500-kV station service voltage transformer (SSVT) is a compact insulation design that provides minimum winding sizes. Since SSVTs are new equipment that combine the operational features of a power transformer and the design features of a measuring voltage transformer, it is necessary to study the characteristic transient processes occurring under the impact of lightning-impulse test voltages and lightning and switching overloads in operation in order to ensure proper insulation design. The article presents the results of an experimental investigation of impulse transients in the windings of a full-scale mockup model of an active part of a 20-kV A SSVT with a rated voltage of 110 kV. The influence of grounding the low-voltage winding terminals on the maximum values and duration of impulse stresses on the longitudinal insulation of the high-voltage winding is revealed. It is shown that, unlike in the case of power transformers with disc windings, more significant effects on the insulation are produced when no load is applied on the low-voltage windings.

This article provides the results of studying the influence of test voltage frequency on the dynamic parameters (dielectric losses and characteristics of partial discharges) of micaceous insulation of stator winding for high-voltage (HV) electric machines. The tests have been conducted using mockup samples of stator insulation with an artificial defect in the front area. It has been established that the low-frequency (0.1 Hz) test voltage increases the dielectric loss tangent and, at the same time, reduces the peak apparent charge of external partial discharges compared to the tests at power frequencies. The established ratios must be taken into account when choosing expert diagnostic evaluations during high-voltage electric-machine tests.

High-voltage transmission lines are powerful industrial sources of electromagnetic noise in electronic mains. Mathematical models describing electromagnetic fields and noise for physical simulation of the effect of high-voltage power lines are developed. The mathematical models, a scheme of the experimental test bench, equipment, and calculated parameters of physical models are the basis of practical methods in physical simulation of electromagnetic interference in electronic mains upon the impact of high-voltage power lines. Examples of implementation of physical simulation of electromagnetic interference confirm the practical suitability of this approach and rather high accuracy of studies (the deviations do not exceed 30%).

Results of experimental studies of electroerosive wear of accelerating channels’ surface of coaxial magneto-plasma accelerator are presented. The main patterns of the accelerating channel electroerosive wear of titanium, stainless-steel, copper, and duralumin coaxial magnetoplasma accelerators (CMPAs) are determined. The optimum length of the accelerating channel in the range of delivered energy in the region of 50 kJ, wherein up to 90% of the material carried out by the hypersonic jet of electroerosion plasma is turned out, are determined. For titanium, stainless steel and duralumin barrels, it is about 150 mm and for a copper one it is 100 mm. The analytic expression allowing one to estimate the required weight value of eroded material with certain energy and structural parameters of CMPA are obtained on the base of experimental studies.

This paper is devoted to the solving problems of structural synthesis and circuit analysis. Within the framework of the method of structural synthesis, each resulting rectified voltage should be considered as the maximum potential difference across the topographic potential plane. The simple statements of the structural synthesis have been adapted and exemplified for uncontrolled single-phase ac rectifiers with increased rectified voltage. The effect of topological structures of the uncontrolled rectifiers on the main parameters has been determined. Ways to develop technical solutions and means to obtain desired properties and parameters of uncontrolled single-phase ac rectifiers have been revealed. In combination with the known analytical methods and computer simulations, this allows one to determine quantitatively the efficiency of circuit design for searching for ways to further improve them.