KillBill7
Electrical
- Feb 10, 2017
- 61
Hello all..... we have 13.8kV distribution line which runs near the costal area and we recently experienced few flasover where the inusulator show arc marks on the top shed and the bottom shed only. Installed insulators are composite type with silicon rubber shed and 40mm/kV creepage distance. Flashover happened during the rain so my assessment is rain created high conductivity solution on the insulator surface that allowed leakage current to flow. The leakage current tends to burn carbon track on the insulator shed which resulted in power arc. What doesnt make sense to me is that there are no burn/arc marks on middle sheds but the arc marks at the bottom shed, so if tracking didn't happend how did the arc reach the bottom shed? I am thinking ,as it was raining, the surroundig air may have become the shortest path for the arc so instead of flowing through insulator surface (tracking) it arced directly from top shed to bottom shed? Any feedback is much appreciated.