Abstract
The multi-chamber arc-extinguishing structure (MAS), which consists of a lot of semi-closed short-gap arc-extinguishing chambers (SSAC) in series, can be used in parallel gap lightning protection devices to improve the ability to extinguish power frequency follow current. The arc-extinguishing ability of single SSAC directly affects the arc-extinguishing performance of the whole MAS. Therefore, the arc-extinguishing performance of MAS can be improved by optimizing single SSACs. A two-dimensional model of the arc plasma in a SSAC is built based on the magneto-hydrodynamic (MHD) theory. The motion characteristics of an arc in the SSAC are simulated and analyzed. An optimization method of the SSAC structure is proposed. Finally, an impact test platform is built to verify the effectiveness of the optimized SSAC structure. Results show that the short-gap arc forms a high-speed airflow in the SSAC and the arc plasma sprays rapidly to the outlet until the arc is extinguished at its current zero-crossing point. The amplitude of airflow velocity in the optimized structure can be increased to about 8-fold the velocity in the basic structure. Experiments also show that the dissipation time of an arc in the optimized SSAC is 79.2 μs, which is much less than that in the original structure (422.4 μs).
Highlights
The parallel gap is a well-known “dredging” type of lightning protection device, widely used in transmission and distribution lines [1,2]
The arc moves far away from the insulator along the parallel gap driven by the electromagnetic force, protecting the insulators and lines from the burning arc, and preventing the breakage accidents caused by arc ablation after lightning flashover [3]
The arc plasma moves outside the chamber, and the arc brightness and arc diameter decrease gradually, as shown in Figure 10 (7)–(11)
Summary
The parallel gap is a well-known “dredging” type of lightning protection device, widely used in transmission and distribution lines [1,2]. The arc moves far away from the insulator along the parallel gap driven by the electromagnetic force, protecting the insulators and lines from the burning arc, and preventing the breakage accidents caused by arc ablation after lightning flashover [3]. The lasting arc could burn the parallel gap device and destroy its protection performance. It is crucial to retrofit the parallel gap with arc-extinguishing capability for lightning protection
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