Long Line Single-Phase Switching Transients and Their Effect on Station Equipment

The influence of single phase switching on long EHV transmission lines and system design is presented. The effect of long lines, transposition schemes, power flow and other system conditions is shown to significantly affect the magnitude and characteristics of secondary arc currents. It is shown that the sustained and transient overvoltages resulting from single phase switching during increased levels of power flow may exceed conventional three phase energizing transients. The relationship between these and other overvoltages and equipment specifications is presented. The effect of single phase switching on an adjacent HVDC terminal is also briefly discussed.