Study on the influence rules of soluble contaminants on flashover voltage of disc suspension insulators

The soluble contaminants existing in external insulation are various, which affect insulator flashover performance. This paper conducted experiment to investigate the flashover performance of disc suspension insulator string polluted by eight kinds of soluble common contaminants respectively. Based on the test data, the influence rules of soluble contaminants on flashover voltage of insulators were analyzed, and the flashover voltage prediction formula based on freely soluble contaminants was proposed. Research results indicate that, the flashover performance of disc suspension insulator string varies with the type of soluble contaminants as well as ESDD (equivalent salt deposit density), negative power function can be used to characterize the relationship between flashover voltage and ESDD; under the same ESDD, sulfates correspond to the highest flashover voltage, while NaCl corresponds to the lowest one; the characteristic exponent n of nitrates are within 0.18 - 0.26, which are higher than that of sulfates but lower than the value of NaCl; the flashover voltage prediction formula based on freely soluble contaminants can be expressed as U
_f
= (b-kn) × ESDD
^-n
, the application of which can reduce the workload and cost of laboratory tests in the external insulation design.