并联电容器装置保护用氧化锌避雷器的选型问题

从我国电力系统实际情况出发 ,结合避雷器选型的历史回顾和新版本的避雷器国家标准 ,提出了使电力系统安全、可靠运行的并联电容器装置用氧化锌避雷器的选型方法 ,对变电站中并联电容器装置的设计具有一定的参考价值     

GFD—360型涂层钢板焊接设备及工艺的开发

本文介绍了本课题组研制、开发成功的GFD－360型涂层钢板，专用点焊机的机械部分、主回路电气、微机控制等原理及其焊接工艺规范。     

阳极铝箔交流腐蚀发孔对比容的影响

采用５０Ｈｚ交流电腐蚀发孔和进一步腐蚀阳极铝箔，在腐蚀箔表面形成透明钝化型腐蚀膜且蚀孔孔径较大。在交流电腐蚀过程中不产生发黑、掉粉和减薄现象。另外，该工艺对盐酸浓度和硫酸添加剂浓度的适应范围很宽。     

Development of Ferroelectric Ceramics with High Dielectric Constant and Low Dissipation Factor for High-Voltage Capacitors

Both ferroelectric BaTiO₃-based and SrTiO₃-based dielectric ceramics with high dielectric constant and low dissipation factor have been successfully developed, and applied into mass production for high-voltage ceramic capacitors. Crystalline phases of the ceramics were identified by XRD. STEM study of the ceramics was also conducted. Based on the computer simulation of a shell-core and two-phase mixed structural model proposed, a novel processing method was employed to produce SrTiO₃-based ceramics with the following satisfactory dielectric properties: dielectric constant at room temperature _20C=2000, dissipation factor at room temperature D _20C=0.003, temperature coefficient of dielectric constant = –8% (–25°C to 85°C), and, breakdown electric field E _b=10kV/mm(dc). Optional composition of BaTiO₃-based ceramics has been obtained through the orthogonal design experimentation: BaTiO₃-xBaZrO₃-yBaSnO₃, where x = 8wt% and y = 6wt%, with minor additions of MnSiO₃, WO₃, CeO₂, Bi₂(SnO₃)₃ and ZnO. Its major properties are as follows: Curie temperature T _c = 21°C, _20C=18,000, D _20'C = 0.008, =–80% (–25°C+85°C) and E _b = 8kV/mm (dc).     

High pass filter with above IC integrated SrTiO3 high K MIM capacitors

This paper describes realization and characterization of SrTiO₃ (STO) high K MIM capacitors above BiCMOS integrated circuit (IC). These capacitances are connected to IC and are used as coupling capacitors in order to realize a high pass filter. Surface capacitance achieved is 10 nF/mm² with capacitance value of 1.2 nF. The process for STO MIM fabrication does not exceed 400 °C, which is compatible with interconnections. Typical K and dielectric losses values obtained are, respectively 110% and 2%. Yield obtained reaches 83% for capacitors. A functional high pass filter using these STO capacitors was realized in this study. It exhibits a cut-off frequency at 6.5 kHz and a constant gain at higher frequencies of −1.3 dB.     

并网风电机组补偿电容器投入过程研究

对风电场并联电容器的投入过程进行了仿真研究。着重研究了投入电容器时的高频涌流及过渡电压降低的现象并提出了有效的改善措施。     

Characterization of ferroresonant modes in HV substation with CB grading capacitors

This paper reports a ferroresonant experience involving inductive voltage transformers (VT's) in a 400 kV substation equipped with circuit breaker grading capacitors. Field measurements are presented and compared with ATP/EMTP simulation results, showing very good agreement. A parametric analysis has been performed to investigate the effect of the substation capacitance on the occurrence of ferroresonance. Fundamental frequency and sub-harmonic ferroresonant modes have been identified and compiled in a bifurcation diagram. The methodology presented can be used to create risk maps of avoidable switching operations or substation configurations.     

Synthesis and properties of manganese-doped barium titanate

An oxalate route for the production of BaTiO₃ has been modified to incorporate Mn (upto 2%) as a dopant and the reaction sequence has been studied. The resulting Mn-doped BaTiO₃ exhibits a dielectric constant with an increasing insensitivity to temperature and applied a.c. field as the Mn content is increased. These samples possess a high electrical resistivity even after treatment in hydrogen at 1100°C and are therefore suitable as dielectric for multilayer capacitors with base metal electrodes.     

Al2O3 deposited by the oxidation of trimethylaluminum as gate insulators in hydrogen sensors

It is known that stable hydrogen sensors can be made with palladium-aluminum oxidesilicon dioxide-silicon (PdMAOS) structures. An improved way of making thin aluminum oxide films on silicon dioxide is presented. It is based on the oxidation of trimethylaluminum in an argon/oxygen atmosphere at 300–400° C. The optical and electrical properties of Al₂O₃ films made with this metal-organic chemical vapor deposition (MOCVD) method are presented. Finally the properties of completed PdMAOS hydrogen sensors are briefly presented.     

Cycle stability of birnessite manganese dioxide for electrochemical capacitors

A combination of step potential electrochemical spectroscopy (SPECS) and electrochemical impedance spectroscopy (EIS) has been used to examine the electrochemical cycling behaviour of a well-characterized birnessite-phase manganese dioxide sample for use in electrochemical capacitors. The resistance and interfacial properties of the macroscopic electrode were found to be irreversible with cycling. However, the corresponding properties for the individual particles were more reversible, although they did show substantial hysteresis in their behaviour during cycling. This behaviour was discussed in terms of the structural, conductivity and morphological characteristics of the birnessite at different depths of discharge.