Externally gapped line arresters a critical design review

Enhancing the lightning performance of overhead transmission lines with optimal EGLA and downstream shield wire placement in mountainous areas: a complete study

“…EGLA consists of the non-linear metal-oxide resistor and a gap distance [8]. Practical work has implemented a field test experiment performed in [34].…”

“…In steady-state conditions, follow current is very small, so in the presence of EGLA, there is no more effect on gap flashover voltage. The gap distance value may obtain by averaging minimum and maximum externally gaps of line arrester as expressed in [8]. By this calculation, CFO pf is 407 kV and an average of the arcing gap is 1675 mm.…”

“…The validation of the insulation coordination of EGLA and insulators is checked in this study based on expressed statements in [8]. Furthermore, the details of the coordination of these types of line arresters have been defined in [39].…”

“…According to IEC 60099-8, a gapped line arrester is applicable for the protection of TLs with higher than 230 kV voltage. It prevents the occurrence of the flashover across the insulator string [8]. The focus of this paper is on this type of surge arrester.…”

“…As explained in [2,14], the minimum lightning current causing back-flashover is low and it has improved in this paper. The authors of [2,8,12] that explained the EGLA advantages, but these papers have not investigated which type of EGLA is more suitable for selection. Some papers such as [15] the impact of surge arresters and ferromagnetic ring on the magnitude of lightning overvoltages in GIS are represented in ATP/EMTP software [16].…”