Effect Of Different Salt And Different Non-soluble Deposit Densities On Flashover Character Of 110kV Composite Insulator

Composite insulator has advantages of less weight, higher mechanical strength, more excellent anti-contaminated characteristic, easier to maintain. Therefore, the composite insulator is widely used by power utilities in many countries. However, as more and more composite insulators are put into service, there are some problems emerging, the unavoidable reason of flashover on composite insulators when contaminated on surface, I think, it may be related with the pollution test method in which the Non-soluble Deposit Density(NSDD) does not be included. Aimed at the problems of composites in operation, in the paper the AC flashover characteristic of polluted composite insulators under the conditions with different ESDD and NSDD is researched by test. Moreover, the AC flashover mechanism and flashover process of composite insulators under the different polluted level is analyzed.According to the test results carried in the artificial fog chamber, this paper analyzes the effects of the equivalent salt deposit density(ESDD) and the non-soluble deposit density(NSDD) on the flashover performance of the 110kV composite insulator. The result shows that the flashover voltage U_f of the 110kV composite insulators decreases with the increase of both ESDD and NSDD by an power function with a negative index that is 0.106 for ESDD and 0.140 for NSDD, which is opposite with a porcelain insulator. Because of the non-soluble deposit can stop the hydrophbicity recovery and has more water which is helpful to soluble of the conductive materials, U_f decreases with the increase of NSDD. By analyse of test datas and experimental results, the formula of flashover voltage of 110kV composite insulator can be expressed as:U_f =110.0ρ^-0.106_ESDDρ^-0.140_NSDD. By analysis of pictures of flashover process under different contaminated level and oscillograms of flashover voltage and leakage current of HOkV composite insulators, the conclusion can be obtained as following:(1)Under different contaminated level, the following flashvoer process of arc may be described: create, blanking, restrike, developing and lead to flash. But the time of arc extinguishments, arc intensity and speed of arc development are different caused by...