Transformer resin impregnated paper(RIP) bushing has been widely applied in power transmission system as a vital part of power transformer. The performance of bushing is important to the reliability ...level and stability of power system. However, as the voltage level increases, the heating problem of resin impregnated paper bushing is increasingly serious. In this paper, a 3-D electromagnetic-fluid-thermal method was proposed by applying computational fluid dynamics(CFD) analysis. The influence of thermal conduction, thermal radiation and convection heat transfer were taken into account and take the resistivity varying with temperature in consideration. The distribution of temperature was obtained; influential factors of environmental temperature, oil temperature and thermal conductivity of resin impregnated paper and sheath were investigated. The highest temperature is located at the interface between the central conductor and resin impregnated paper core. The effect law of different factors to the temperature distribution could provide reference for the thermal design of bushings.
Gas insulated metal enclosed line (GIL) has a lot of advantages on electromagnetic environment, current capacity and stability. As for the unique characteristic of GIL, mature products of GIL are ...more preferable to the high voltage transmission field in some situations. With the voltage level increasing, the insulation designs have a high level of challenges and difficulties. The world's first 1100 kV GIL has been building in China from Suzhou to Nantong. In order to ensure the safety and stability of this transmission projects, improve the reliability of the electrical insulted system, it is necessary to optimize the structure of GIL. In this paper, based on the structure of the GIL, the full three-dimensional (3D) finite-element method (FEM) model was built for numerical simulation. Then, the electric field distribution was calculated by COMSOL Multiphysis and the key parameters including radius of the post, width and inclination angle of dumbbell structure and some other parameters were changed to tell the effect law of dumbbell type structure to the electric field distribution. The results indicated that the change of different parameters will have different effects on the electric field distribution. The research conclusions can provide reference for insulation structure design and the GIL tri-post insulator production.
UHV AC GIS Basin type insulator is the key component of the gas insulated substation (GIS). The stability and reliability operation determines the insulation strength level of GIS. However, because ...of the characteristic of switchgear in GIS, the very fast transient overvoltage (VFTO) occurs with high frequency, amplitude and gradient, which will threaten the safety of insulation. In the past time, electric field distribution with VFTO was calculated by traditional method which used the peak voltage as the boundary condition. In this paper, a transient method which have the effect of wave front in consideration was proposed. A circuit model of GIS was built to simulate the VFTO, and than a equivalent bevel flat top wave of VFTO was used to be a boundary condition. Eventually, a basic finite element model was established by using COMSOL, and the electric field was obtained when the wave pass through center conductor in instantaneous condition. Electric field distribution in different time were shown. Results indicated that when the wave process was in consideration, the electric field will be distorted and comparing with traditional method, it will make the electric strength increase.
Titanium oxide coatings(TiO 2 /Ti) were formed on the titanium surface by micro-arc oxidation(MAO) in Na 3 PO 4 solution.The photocatalytic ability of titanium oxide coatings were evaluated by ...photocatalytic degradation of Rhodamine B aqueous solution. Using the TiO 2 /Ti as anod electrode, the titanium as counter electrode,and with the UV lamp,constant current meter make up the photoelectrocatalytic reactor was built. We have studied the effect of the initial concentration, pH, the concentration of electrolyte, and different anions on the photoelectrocatalytic degradation of Rhodamine B solution. It is found that the impacts of different conditions are different. With the increase of the initial concentration and pH, the removal of Rhodamine B is decreased. The impacts of different anions are also notable, but all of them can improve the efficiency of photoelectrocatalytic. From these studies above, under the conditions are follows, coating TiO 2 film electrode in 5 minutes, the initial concentration is 1.5mg/L, the value of pH is three, the concentration of electrolyte is 0.02mol/L, the effect of photoelectrocatalytic treatment of dye wastewater is best.
The structural characteristics, deposition rate, absorption spectra and optical band gap of the silicon-germanium thin films, which were prepared by RF-PECVD, had been researched under the diffferent ...Germane's concentration. By test of Raman, all the silicon-germanium thin films presented amorphous and the spectral peaks were located around 480cm-1. According to the trend of optical band gap, the band gap of film could be adjusted effectively by increasing the concentration of Germane in the reactive gases. Also, the absorption in the long-wave region and the response to the solar spectrum were able to be improved and expanded.
Prepared a-SiC thin films with plasma enhanced chemical vapor deposition (PECVD) at low temperature (135°C), by using CH 4 , H 2 , SiH 4 and B 2 H 6 . And with Raman spectroscopy, ellipsometry, ...absorption spectroscopy and other equipment to demonstrate the film characteristics such as structural characteristics, growth rate characteristics, band gap and refractive index spectra. The results show that we facbricate amorphous silicon carbide successfully under the condition of flow 80 sccm, RF power 24 w, working pressure 74 pa, substrate temperature 132°C.
Dropwise condensation on Nickel-based alloy coating (NBAC) tube has been experimentally investigated. In addition, the mechanism of dropwise condensation facilitated by the nickel-based alloy coating ...tube has been analyzed. All the work done provides scientific basis for the further research and application of the new surface modification technology.
