Zhang S.-Q.,Henan Pinggao Toshiba High Voltage Switchgear Co.
Gaoya Dianqi/High Voltage Apparatus | Year: 2012
Current transformer (CT) is a key component that links high voltage primary circuit and control protection circuit. This paper ascertains the structural dimension of CT on the basis of electromagnetic conversion principle. It is found that the leakage flux and exciting current are main sources to introduce the error of CT, and the exciting current depends on electrical parameters, core material and structural dimension of CT. It is demonstrated that uniformly distributed secondary windings of CT can minimize the leakage flux, and indirect test and direct test of composite error are equivalent only for the CT with uniform distribution of tapped windings. On the premise that performance requirements of CT are met, the error and manufacturing cost of CT can be reduced by appropriately changing CT's electrical parameters, such as grading load of the CT with multi-tapped windings, and changing duty cycle of the CT with transient protection and without reclosing requirement from double-cycle to single-cycle. In addition, the selection of insulation materials for internal CT and the moisture resistance for external CT are described. Especially, the reason why closed circuit is formed in spot installation of external CT, the effect of the closed circuit on CT's error, and the methods for detecting the closed circuits are discussed.
Zhu L.-N.,Henan Pinggao Toshiba High Voltage Switchgear Co.
Gaoya Dianqi/High Voltage Apparatus | Year: 2012
Presently, in view of the problems in storage, transport of the GIS, a structure of GIS positive pressure storage, transportation is established. This structure not only provides a way for the storage transportation of the GIS, but also provides a theoretical calculation method for the design of the key component of this kind of structure. Through the experiments, this structure and the calculation method comply with the design expectation, so as to prove the rationality of the structure and the reliability of the calculation method.
Xi C.,Zhoukou Normal University |
Zhenjie W.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Xuelin L.,Medical Instrument Testing Institute of Henan Province |
Jie W.,Zhengzhou University |
Zhanwei C.,Zhoukou Normal University
Research Journal of Applied Sciences, Engineering and Technology | Year: 2013
Gaussian and Sigmoid membership function are commonly used, both of which have well smoothness, clear physical meaning and have no zeros in their figures. In this paper, fuzzy density means clustering method based on data distance is put forward, by using this method, the initial cluster center is obtained objectively, which has avoided the cluster results falling into a local minimum, finally the parameters used for describe the membership function are got. Through simulation, the membership function of data EB_Da51 in petroleum drilling is determined, which solves the problem that the function is hard to be defined. © Maxwell Scientific Organization, 2013.
Su G.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Qin X.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Li S.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Liu F.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Shi F.,Henan Pinggao Toshiba High Voltage Switchgear Co.
Gaoya Dianqi/High Voltage Apparatus | Year: 2015
The electromagnetic voltage transformer(VT) configured in 550 kV GIS can generate ferroresonance under some special operating conditions. Through analyzing the causes of ferroresonance, it is concluded that the series LC circuit constituted by shunt capacitance between GCB breaks, the bus to earth capacitance in GIS, and the nonlinear inductance of VT are the main factors to generate ferroresonance. The T-area of 3/2 connection or 4/3 connection is the most dangerous operating condition. Furthermore, through validating ferroresonance by using EMTP analytical method, it is concluded that additional saturable reactor can effectively restrain ferroresonance. ©, 2015, Xi'an High Voltage Apparatus Research Institute. All right reserved.
Zhang W.-J.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Zhang S.-Q.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Zhang K.-X.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
Liu Y.-J.,Henan Pinggao Toshiba High Voltage Switchgear Co. |
And 2 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2013
The manufacturing technology progress, design and manufacture of miscellaneous high voltage devices are more and more perfect and gradually formed their own complete quality control system nowadays. But problems in the connection between different equipment onsite appear continuously due to different manufacturers supply different main equipement. Common main equipment connected to GIS are power transformer (or reactor), power cable and gas insulated lines (GIL) etc. This paper explains main points of direct connection mode and gives feasible measures. Direct connection docking part shall be set to detachable independent gas chamber, its interface size and supply division shall enough be communicated within different manufacturers or utilities. In this paper, the problems and solutions of direct connections of GIS to transformer, cable and GIL are analyzed such as connection size, installation space, mechanical stress and acceptance test.