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Zhuzhou, China

Li Q.,Zhuzhou Times New Material Technology Co. | Zhong J.,Zhuzhou Times New Material Technology Co. | Li Y.,Zhuzhou Times New Material Technology Co. | Wang K.,Zhuzhou Times New Material Technology Co. | And 2 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation

In this paper, a new class of C-grade solvent-free silicone impregnating varnish was prepared by synthesizing polysilicone oligomers bearing methyl and phenyl groups. These oligomers also contained vinyl and hydrogen siloxane components which, under the influence of heat and platinum catalysis, induced crosslinking of the impregnating varnish. The varnish without any solvents kept liquid and flowed easily at room temperature (RT) and was heated to cure to a rigid membrane at high temperature up to 473 K. The properties of the varnish before and after curing were depicted in details, and the mechanism for synthesis of the solvent-free silicone impregnating varnish was introduced. The solvent-free silicone impregnating varnish was used on the winding as dielectric shield for a motor or electric device by vacuum pressure impregnation (VPI) which is the most conventional method for impregnation of the winding for a motor. The silicone varnish, which contained no decomposable and physiologically problematic components, was of very low volatility suitable for VPI. The application technology and processing conditions of the silicone impregnating varnish were discussed in details and a simulant procedure and a practical sketch about the four steps involved in the VPI process employing the silicone impregnating varnish were illustrated. © 2006 IEEE. Source

Xu J.,Hunan University | Liang X.,CSR Electrical Motor Co. | Yao X.,Hunan University | Liao W.,Hunan University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

In order to solve the engineering problems, such as complex establishment of the multi-winding transformer model, long calculation time of composite short-circuit impedance and difficulties in calculation of the circulating current for parallel windings, a solution method for composite short-circuit impedance and circulating current in the parallel windings was proposed based on the equivalent single-turn inductance matrix and the equivalent circuit model of the transformer described by self-inductance and mutual inductance. In this method, all the short-circuit impedance between any two windings were computed by the equivalent single-turn inductance matrix. Combining the definition of composite short-circuit impedance with the ports' conditions, all concerned composite short-circuit impedance and the circulating currents could be calculated only once through compiling the corresponding general calculation procedure in Matlab. Finally, taking a twelve-winding transformer as an example, the results calculated by the proposed new method were compared with the testing ones, which indicates that the calculation results of composite short-circuit impedance can meet the engineering requirements. © 2011 Chinese Society for Electrical Engineering. Source

Xu J.,Hunan University | Qi Q.,Hunan University | Li Z.,Hunan University | Huang D.,CSR Electrical Motor Co. | Li G.,CSR Electrical Motor Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

In multisystem electric locomotives, when the traction main transformer plays two roles as the transformer and the DC filter reactor, it can increase the device availability of traction systems and can decrease the space and weight. For solving the problems including establishing its nonlinear and complicated model of calculating the filter inductance, taking the port voltage equations of the multi-winding transformer into account, a new method was proposed to calculate the DC filter inductance based on the reduced-order inductance matrix. Firstly, the common expression of the reduced-order inductance matrix was deduced. Then according to different winding connecting schemes, the port voltage equations were established, and the parameters in the reduced-order inductance matrix substitute the ones in the equations. Afterwards, based on the port boundary conditions, the calculating expression of the filter inductance was obtained. Lastly, taking the South Africa multisystem traction transformer for example, the results calculated by the proposed method were compared with the testing ones under two classical connecting schemes, which indicates that the proposed method can calculate the DC filter inductance accurately. It is of important engineering value to match optimally impedances of the traction transformer with system parameters in the multisystem electric locomotive. © 2015 Chin. Soc. for Elec. Eng. Source

Xu J.,Hunan University | He J.,Hunan University | Yan X.,Hunan University | Tong H.,CSR Electrical Motor Co. | Huang H.,CSR Electrical Motor Co.
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society

In order to research on the voltage distribution in transformer winding suffering from the lightning surge, a simulation model of 160-turn winding based on multi-conductor transmission line (MTL) theory is established and a new method for the calculation of voltage distribution is proposed in the paper. Firstly, the finite element method (FEM) is adopted to calculate the electric parameters R, L, C and G of windings. Secondly, the voltage transfer functions are obtained by solving the MTL equations under multiple frequencies. Then, the voltage transfer functions are fitted with rational functions by vector fitting. Lastly, the voltage response in transformer winding is shaped through the convolution between the voltage transfer functions and the excitation. The simulation result confirms the validity of this proposed methodology. This research is of great significance for the insulation design of transformer. Source

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