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In order to determine the required live working safety distance for 750kV double circuit transmission line in different altitude areas of China, by using the test data of 750kV double circuit transmission line in the low altitude areas, and combining the common altitude correction methods, the live working safety distances of different altitude correction methods are obtained. By comparing and analyzing the results of different analysis methods, the required minimum approach distances and minimum combined gap distances of live working are recommended under different working conditions in the altitude of 1000m ~ 5000m areas. The results could provide technical reference for 750kV double circuit transmission line in different altitude areas.

External insulation design of UHV power project is important. The lightning impulse (LI) voltage is one of the main factors that determine the air gap distance. Based on existing LI voltage results of power project typical gap, impact of gap structure and distance on LI discharge correction is analyzed. And from a theoretical aspect, existing LI discharge correction methods are summarized. Furthermore, by the use of common correction methods, LI voltage correction factors of rod - plane were calculated and analyzed. Results show no significant impact of gap type or gap distance on LI voltage correction is found out. Average atmospheric conditions are effective when atmospheric parameters method is used for LI voltage correction. DL/T 620, IEC 60060-1 and IEC 60071-2 can be used for LI voltage correction at areas with altitudes of 1000-5000m. While GB311.3-improvement method can be used for LI voltage correction at areas with altitudes blow 4000m.