DC Flashover Performance of Various Types of Ice-Covered Insulator Strings under Low Air Pressure

Abstract

Abstract:In this study, icing flashover performance tests of typical DC porcelain, glass, and composite insulators are systematically carried out in a multifunction artificial climate chamber. The DC icing flashover voltages of seven typical insulators under various conditions of icing thickness, pollution severity before icing, string length, and atmospheric pressure are obtained. The relationships between icing thickness, salt deposit density as well as atmospheric pressure and the 50% icing flashover voltage are analyzed, and the formulas are obtained by regression method. In addition, the DC icing flashover voltage correction method of typical porcelain, glass, and composite insulator in the coexisting condition of high altitude, contamination, and icing is proposed.

DC Flashover Performance of Ice-Covered Composite Insulators with Parallel Air Gaps

“…However, when the flashover occurs along the surface of ice-covered insulator, U50% decreases with an increase of SDD. For example, for Sample A with h of 100 mm and d of 10 mm, when SDD was 0.05 mg/cm 2 , the U50% was 71.3 kV; when SDD was increased to 0.08 mg/cm 2 , the U50% was 64.6 kV with an decrease of 9.3%; for Sample B with h of 100 mm and d of 10 mm, when SDD was 0.05 mg/cm 2 , the U50% was 46.9 kV; when SDD was increased to 0.08 mg/cm 2 the U50% was 42.6 kV, with the latter decreasing by 9.2%, so, when the discharge path is along the insulator surface, the influence of SDD on U50% of ice-covered CI/PAGs is consistent with that of ordinary ice-covered composite insulators [18,19].…”

“…The available research results show that the flashover voltages of ordinary insulators decrease with the increase of the ice thickness d and the U50% can be expressed as a power function of d with a negative characteristic exponent [1,13,18,19]. The test results in this study also reveal that with an increased ice thickness d, the U50%s of iced CI/PAGs decreases gradually.…”

“…For ordinary insulators, with the increase of contamination parameter SDD, U50% decreases accordingly in a power function [18,19]. The test results in Tables 3 and 4 present that when air gap breakdown occurs on the ice-covered CI/PAG, there are some deviations as to the U50% under different SDDs, but such differences are small and within the experimental tolerances.…”

“…Based on the above analysis, the ice thickness exhibits more effects on DC negative flashover voltage of Sample B than on that of Sample A. When the parallel air gap distance is relatively large and flashover occurs along the insulator surface, the influence of ice thickness d on U50% of CI/PAG is the same as that of ordinary ice-covered composite insulators [17][18][19][20]. For Sample A with h of 100 mm and SDD of 0.05 mg/cm 2 , when d = 10 mm, the U50% was 71.3 kV; when d = 20 mm, the U50% was 59.2 kV, with the latter dropping by 16.7%.…”

“…The technical parameters of DC test power supply are as follows: power supply = AC 10 kV, maximum output voltage = 600 kV, ripple factor of the test voltage for a 500 mA current with a resistive load <3%, relative voltage drop occurring during individual tests resulting in withstand ≤5%, and relative voltage overshoot due to load-release caused by the extinction of electrical discharges on insulator surface ≤8%. The test voltage was measured by ZGF-600 resistive potential divider with a precision of 0.5% (for more details see [19]). …”