Research of Degradation Performance of 35kV MOA under Lightning Impulses
Hu Wang · Insulators and Surge Arresters · 2014
The low current and the residual voltage characteristics of the 35 kV metal oxide arrester(MOA) are studied under the continuous applications of 8/20 μs impulse current. The degradation feature and damage mechanism of the varistors in the MOA are also researched. There is a threshold of impulse application number(850) when the 35 kV MOA are applied by continuous lightning impulses.The low current and the residual voltage characteristics will keep constant if the impulse application number is less than the threshold. But, if the impulse application number is greater than the threshold,the residual voltage characteristics will degraded obviously. The damage of MOA resulted from lightning impulse is mainly caused by the surface flashover along the varistors, and such flashover often occur at grounding terminal of MOA in the beginning stage. The ZnO varistor will present the directional deviation after the stresses by lightning impulses. The study results will supply the experimental basis to evaluate the degradation life and to prevent damage of 35 kV MOA in service.