Analysis of air gap correction method for 27.5kV traction power supply system of Highland electrified railway

This paper compared air gap and tolerance voltages correction methods on high altitude area, and based on them we analyze correction method considering the special environmental conditions of Sichuan-Tibet railway. With test results of short air gap in different areas of China, we verified the adaptability of insulation gap correction method at an altitude of 4000 to 4500m. As a result, we formulated a correction method and value of air external insulation under 50Hz overvoltage and lightning impulse overvoltage of 27.5kV traction power supply system at an altitude of 4000m to 4500m.