Jiang Xingliang

AC flashover performance and voltage correction of 27.5 and 110 kV iced composite insulator at 4000/spl sim/5500 m high altitude districts

Based on the test results carried out in the multi-function artificial climate chamber of Chongqing University (China) on two types of composite insulator, this paper discusses the effects of atmospheric pressures or altitudes, contamination level and ice amount secreted on the minimum AC flashover voltages of composite insulators, and analyzes the flashover performance of the composite insulator in icing, contaminating and low pressure conditions. The authors therefore put forward a correction method of flashover voltages.

Study of flashover performance and voltage correction of DC insulator in icing districts of altitude of 2500 m and below

Based on the results of the DC flashover tests of iced XZP-160, XZP-300 and XWP4-160 insulators carried out in the artificial climate chamber in the High Voltage Laboratory of Chongqing University, China, this paper analyses the effects of altitude and ice on the DC flashover voltage of the three types of insulator. The relations between the DC flashover voltage of iced insulators at high altitude or low atmospheric pressure and the ice amount accreted, as well as the effect of voltage polarity on flashover voltage have been obtained. A voltage correction formula for iced insulators in low atmospheric pressure is also put forward.

Effects of Non-uniform Pollution on the AC Flashover Performance of Suspension Insulators

The non-uniform distribution of contamination on insulator surface has appreciable effects on flashover voltage, and corresponding researches are valuable for the better selection of outdoor insulation. In this paper, two typical types of porcelain and glass insulators which are widely used in ac lines were taken as the research subjects, and their corrections of AC flashover voltage under nonuniform pollution were studied. Besides, their flashover characteristics under different ratio (T/B) of top to bottom surface salt deposit density (SDD) were investigated, including the analysis of flashover voltage, surface pollution layer conductivity and critical leakage current. Test results gave the modified formulas for predicting flashover voltage of the two samples, which can be directly applied in the transmission line design. Also, the analysis delivered that, the basic reason why the flashover voltage increases with the decrease of T/B, is due to the decrease of equivalent surface conductivity of the whole surface and the decrease of critical leakage current. This research will be of certain value in providing references for outdoor insulation selection, as well as in proposing more information for revealing pollution flashover mechanism.