Correlation Between Geometrical Parameters of Electrical Tree and Corresponding Partial Discharge Parameters in XLPE

This paper deals with the experiemental study on the correlation between the geometrical parameters of electrical tree and corresponding partial discharge (PD) characteristic parameters in the course of eletrical tree aging within cross linked polyethylene (XLPE) insulation. The electrical tree aging tests were performed on specimens removed from a section of 220 kV transmission cable. The PD macroscopic characteristic parameters were found to be significantly dependent on the corresponding geometrical parameters of eletrical tree channels in the course of aging of XLPE, and different kind of electrical tree has different characteristics, and there is obvious correlation between the type of electrical tree and the pre-applied power-frequency stress. Beside, using regression analysis, the expression of the relation between them were obtained, and from which it can be seen that there is significant nonlinear correlation between geometrical parameters of electrical tree and corresponding PD characteristic parameters in the course of aging of XLPE. Therefore, the aging degree of XLPE can be effectively evaluated by recognizing the changing regularity of the PD macroscopic characteristic parameters. Key words XLPE - electrical tree aging - partial discharge - mathematical model CLC number TM 121 Foundation item: Supported by the National Natural Science Foundation of China (59677018)Biography: Wang Hong-xin (1963-), male, Associate professor, Postdoctoral fellows, research direction: electrical insulation condition monitoring, EMC

An Optical Investigation of Silver Nanoclusters Composite Soda-lime Glass Formed by Electric Field Assisted Diffusion

Silver nanoclusters（NCs） embedded in soda-lime glass was synthesized by the electric fieldassisted diffusion（EFAD） and successive annealing. The samples were characterized by UV-Vis absorption spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy（XPS）, and lifetime measurements. The experimental results show that the growth of silver clusters is favored by the annealing temperature and dwell time. The as-diffused and annealed glass samples show photoluminescence around 550 nm under UV excitation, which can be associated with the presence of L-center and Ag3~＋ cluster. And the increasing of the annealing temperature and dwell time results in an appearance of the SPR peak and the decreasing of the luminescence intensities because the Ag3~＋ clusters grow up into the Ag nanoparticles.

Precipitation Behavior of Cu-1.9Be-0.3Ni-0.15Co Alloy During Aging

In this paper,the evolutions of microstructure and mechanical properties of Cu-l.9Be-0.3Ni-0.15Co alloy were studied.The alloys in the condition of the solution treated（soft state） and 37% cold rolled（hard state） were aged at 320 ℃for different time,respectively.The mechanical properties,electrical conductivity and microstructure of the alloy aged for different time were analyzed.Additionally,the precipitation kinetics of Cu-1.9Be-0.3Ni-0.15Co alloys was investigated.X-ray diffraction and transmission electron microscopy results reveal that both continuous precipitation and discontinuous precipitation existed in the hard-state Cu-l.9Be-0.3Ni-0.15Co alloy during the whole aging process;the sequence of continuous precipitation is G.P.zone →γ″→γ′→γ.Furthermore,the precipitation transformation mechanism of softstate alloy is homogeneous nucleation,while hard-state alloy shows the heterogeneous nucleation（interface nucleation）with the nucleation rate of both states decaying rapidly to zero during aging at 320 ℃.

Stable dielectric response in lead-free relaxor K_(0.5)Na_(0.5)NbO_(3)-SrTiO_(3) thin films

K_(0.5)Na_(0.5)NbO_(3)-SrTiO_(3)(KNN-STO)thin films of different compositions were prepared by the chemical solution deposition method.While structural investigations confirmed the formation of perovskite solid solution in all developed films,dieletric experiments revealed a relaxor broad dispersive maximum in the sample with 15 mol%of STO,exhibiting for a thin film high ε′~330 at~210K.The history-dependent effects of this relaxor sample were compared to those of KNN STO ceramics and,furthermore,shown to be much weaker than in widely used lead-based ferroelectric and relaxor(Pb,L a)(Zr,Ti)O_(3) ceramics:While fatigue endurance results revealed a slight drop in polarization after 3 × 10^(5) switching cycles,the results of aging of the dielectric constant revealed no notable decrease in its values after 10^(6)s.