The idea of system control and monitoring of a complete medium-voltage switchgear with solid insulation

The idea of the system control and monitoring of a complete 35-kV switchgear with the shielded solid insulation is presented. The switchgear is constructed in the form of two cells. One of the cells, which has a three-position sulphur hexafluoride load break–disconnecting–grounding switch with a motor-spring drive is incorporated into the switch module and includes bus and cable modules, a cell cabinet, and a control and monitoring system. The other cell contains the same elements, plus a fuse and a high-speed grounding switch. The control and monitoring system is developed in two forms, one for standard and one for digital substations. Technical characteristics and the structure of the system, as well as the execution algorithms, are given. Monitoring of the electromagnetic fields and partial discharges with the use of the various indicators and sensors, monitoring of insulation, and its temperature, as well as residual life of the switching devices and drives, are of great significance. Modbus is usually used as the automation protocol for standard substations. It allows carrying out the dispatching control and data integration into the control system, but it does not allow real-time transmission of the instantaneous values of current and voltage, RPA discrete signals, etc. In accordance with the IEC 61850 standards, all real-time commutation processes are carried out by the Ethernet technology, which is described by the IEEE 802.3 protocol and provides digital data transfer in accordance with stringent RPA requirements. Structural implementation of two system modifications in the form of the nonstandard telecommunication equipment with a temperature–humidity control system located on the top of the switchgear cabinet with the arrangement of the control, indication, and alarm element is described.     

Effect of Reaction Solvent on the Hydrogenation of Isophthalonitrile for Meta‐Xylylendiamine Preparation

This study focused on the effects of reaction solvent on the hydrogenation of isophthalonitrile (IPN) to produce m‐Xylylenediamine (MXDA) over Ni‐based commercial catalyst. The hydrogenation was carried out using various reaction solvents such as 1‐methylimidazole, mesitylene, benzyl ether and isopropanol under various reaction conditions. It was observed that 1‐methylimiazole outperformed the other reaction solvent, exhibiting a high MXDA yield and producing a low concentration of undesirable products.     

Preparation of mesoporous silica fiber matrix for VOC removal

A novel method for the preparation of the mesoporous silica fiber matrix was introduced for a removal of volatile organic compounds (VOCs). Paper making technology was applied to make a sheet of mesoporous silica fiber matrix. Reinforcing the mesoporous silica fiber with the ceramic fibers (50 wt.%) increased the mechanical strength of the matrix. Mesoporous silica fibers using TMOS (tetramethoxysilane) as a silica source and CTAC (cetyltrimethyl-ammoniumchloride) as a surfactant were drawn by the spinning method. The spinning process increased both the crystallinity and the fraction of mesopores (1.9 nm) of the fiber. As the spinning rate was increased both the crystallinity and the specific area of the mesoporous silica fiber increased, but the diameter of fiber decreased. We could control the size and morphology of mesoporous silica fiber matrix by changing the shape of substrates. This leads to easy fabrication of honeycomb-structured adsorbent which can be used for the VOC removal.     

Investigation of the physical properties of iron nanoparticles in the course of the melting and solidification

The processes of iron-nanoparticles melting and iron-nanodroes solidification have been studied under different thermal actions. The determined values of the phase-transition temperatures for particles with radii of 1.5–4 nm agree with the data calculated by other authors. In the course of calculating the solidification of iron nanoparticles, the dependence of the solidification temperature on the rate of heat removal has been found and the hysteresis of the phase transition has been demonstrated. Based on the determined caloric curves, the heat capacity of the particles has been found and their approximation in the form of dependences on temperature and particle size has been suggested.     

An integral method for measuring the <Emphasis Type="Italic">P</Emphasis>-odd asymmetry on a reactor at neutron polarization switching frequencies higher than the frequencies of the main spectrum of the neutron noise power

P-odd asymmetry is measured when frequencies of switching neutron polarization exceed the frequencies of the reactor power fluctuations that govern the spectral density of noise power. A principle for recording the current signals in these measurements is described. This method was used for the first time at the Konstantinov Institute of Nuclear Physics in Gatchina (Russia). The results suggest that the accuracy of measurements at an increased equipment-switching frequency is even higher than the accuracy obtained using compensation for reactor power fluctuations; hence, this compensation becomes superfluous. Following this method, it is possible to take measurements with a single detector and to dispense with a monitor, thereby rendering the equipment and the measuring technique less complex. A strategy of measurements was developed. An experimental model of the facility was produced and tested with a small-amplitude calibration signal in the presence of reactor power fluctuations caused by rays from reaction ¹⁰B(n )⁷ Li* ⁷Li + . The results from the test measurements of the P-odd effect in reaction ³⁵Cl(n, )³⁶Cl are presented.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 62–71.Original Russian Text Copyright ¢ 2004 by Vesna, Shulgina.     

Hardness of superhard polycrystalline materials and its temperature dependence

Data on the hardness and fracture toughness of diamond and cubic boron nitride-based polycrystalline superhard materials and the temperature dependence of these materials’ hardness have been considered. It has been found that the temperature dependence of hardness of polycrystals, based on diamond and boron nitride, produced from powders having various dispersions, shows a decrease in hardness of all the materials and difference in the materials thermostability.     

Fem prediction of the influence of warm prestressing on fracture toughness of heat-resistant steel

We present a procedure of prediction of the influence of warm prestressing combined with cycling on the brittle strength of steel 15Kh2MFA. Using a finite-element method, the effect of the combined warm prestressing on the stress-strain state at a fatigue crack tip is studied in an elastic-plastic statement. Electron microscopic observations of fracture surfaces have revealed that fracture is initiated at some distance from the fatigue crack front. Based on the pattern of influence of the plastic prestrain level on the cleavage stress of steel 15Kh2MFA and the experimental CID value, a method is put forward for finite-element modeling of the stress-strain state at a crack tip during the specimen fracture. Using the results of the finite-element modeling, the relevant curves have been plotted and an approximating formula has been proposed to represent the influence of the combined warm prestress level on the fracture toughness of steel 15Kh2MFA.     

On the use of hyperbolic function to describe fatigue <Emphasis Type="Italic">S-N</Emphasis> curve

We analyze the peculiarities of hyperbolic functions describing S-N curves as applied to a welded joint of mild and alloyed steels. We have demonstrated that the parameter σ_u used in σ-N equation does not generally correspond to the ultimate strength of the material, as it is commonly assumed. Methods for calculating the parameters of hyperbolic equations of S-N curves are proposed for cases, where the endurance limits are unknown or experimentally determined. __________ Translated from Problemy Prochnosti, No. 4, pp. 77–89, July–August, 2007.     

Deposits of excess carbonitride phase in microalloyed steel coils and sheet with different cooling conditions

Deposits of the carbonitrides (Ti, Nb)(C, N), Nb(C, N), and (Nb, V)(C, N) in the austenite and ferrite phases of X70 steel sheet after thermomechanical treatment are investigated. Nb(C, N) particles measuring up to 10 nm are seen in austenite in the final stage of rolling and after its conclusion prior to accelerated cooling of thick sheet. After intense accelerated cooling, most of the niobium and vanadium is retained in the solid solution, as confirmed by the vigorous deposition of (Nb, V)(C, N) particles measuring ∼2–4 nm in ferrite after tempering at 600°C. In coil production, the particles observed may be the result of general deposition or interphase deposition, depending on the cooling of the strip on the output roller conveyer of the continuous broad-strip mill. Carbonitride particles measuring 2–8 nm are deposited at winding temperatures of 550–570°C in steel with niobium and vanadium and at 590°C in steel without vanadium.