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Gao W.,Xian High Voltage Apparatus Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2012

DC switchgear is the key device in the DC transmission system convert station and is applied to the commutation of various operate manner, clearance of the fault, maintenance and disconnect in the DC transmission system, which influences the reliability, availability and maintainability of the transmission system. According to the relative GB standards, technical guidelines and rules as theoretical support, on the basis of the specific requirement of various operate manner and control strategy in the DC transmission system for DC switchgear structure. The purpose and the class is discussed include DC transfer switches, disconnectors, earthing switches and by-pass switches. The analysis and contrast is carried out for DC switchgear based on the basic principle, structure type and characteristic. The technical difficulties and development trends of DC switchgear are put forward. This study provides a reference for the relative researchers and project designers. Source

Wang T.,Xian High Voltage Apparatus Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

In this paper, the diagram of earth fault test-duty D6a of switch in accordance with GB 3804-2004 is analyzed. The test current and recovery voltage parameters have been simulated and calculated by using PSCAD software analysis system, and the results from three methods: simulation results, theoretical calculation results and actual test results, are compared, exactly the same results. Source

Li Y.,Xianyang Normal University | Cao R.,Xian High Voltage Apparatus Research Institute
International Journal of Electronics | Year: 2016

In the light of nullor-mirror models for current-controlled current conveyor trans-conductance amplifier (CCCCTA), initiating the admittance matrices of the Tow-Thomas (T-T) filter, three different types of the T-T filter are synthesised by means of the nodal admittance matrix (NAM) expansion method. The type A filter, which employ one CCCCTA, one grounded resistor and two grounded capacitors, has eight different forms, the type B filter, which employ one CCCCTA, two grounded capacitors and a second-generation current-controlled conveyor (CCCII) or an second-generation inverting current-controlled conveyor (ICCCII) or an operational trans-conductance amplifier (OTA), has 64 different forms and the type C filter employing one CCCCTA and two grounded capacitors has eight different forms. In all, 80 voltage-mode/current-mode T-T filter circuits are obtained. Because of using canonic number components, the circuits are highly desirable from the viewpoint of IC fabrication and their parameters can be electronically tuned through tuning bias currents of CCCCTAs. The hand analysis and computer simulation results have been provided to support the synthesis method. © 2015 Taylor & Francis. Source

Yang X.-C.,Xian High Voltage Apparatus Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2013

The diagnosis, testing and treatment of the vibration fault occurred in a set of 6500 MV·A short circuit generator in operation are discussed in this paper. Also the vibration mechanics are studied theoretically. Some measures are taken to decrease the vibration amplitudes such as determining the vibration nature through testing and analysis, dynamic balance, etc. The results got from this study can be referred to similar faults of generators. Source

Zhang S.,Xian High Voltage Apparatus Research Institute | Ding L.,Shaanxi Normal University | Lu F.,Shaanxi Normal University | Liu T.,Shaanxi Normal University | Fang Y.,Shaanxi Normal University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2012

The detection of nitroaromatics in aqueous solutions by a novel pyrene-functionalized film has been investigated in the present study. The pyrene moieties were attached on the glass surface via a long flexible spacer based on self-assembled monolayer technique. Steady-state fluorescence measurements revealed that these surface-attached pyrene moieties exhibited both monomer and excimer emission. Nitroaromatics such as 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrophenol (picric acid) were found to efficiently quench the fluorescence emission of this film. The quenching results demonstrated that the excimer emission of these surface-confined pyrene moieties is more sensitive to the presence of nitroaromatics than the monomer emission. The quenching mechanism was examined through fluorescence lifetime measurement and it revealed that the quenching is static in nature and may be caused by electron transfer from the polycyclic aromatics to the nitroaromatics. Furthermore, the response of the film to nitroaromatics is fast and reversible, and the obtained film shows promising potentials in detecting explosives in aqueous environment. © 2012 Elsevier B.V. All rights reserved. Source

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