Analysis of Measures for Reducing Tripping Rate of Lightning Stroke on Transmission Line

The design of insulation co-ordination of tower top on transmission line was usually determined by maximum working voltage and switching overvoltage as well as power-frequency leakage rate. The spacing of tower top,the number of insulator,was basically fixed according to checking its lightning impulse withstand level by lightning surge characteristic,which made tripping rate 10: 1 ~ 12: 1 caused by flashover of insulator string and air gap breakdown discharge of tower top,and made the fault rate of transmission line taken 80% of electrical equipment fault around,at the same time,which also limited to increase structural altitude of external insulation disposition under the present condition of serious polluted environment. The paper put forward that the insulation co-ordination of tower top was designed according to adaptability ratio 0.7 (breakdown voltage of air gap/flashover voltage of insulator string),and I string was replaced by V string to form the compact line,which economized line corridor resource and increased the value of creeping flashover voltage of insulator string,and reduced the number of line tripping. The pollution grade of external insulation can be improved to 3.5 cm/kV more,and sweep work of insulator string can be basically avoided,the cost of operation and maintenance can be reduced,the goal of "to reduce labour power and increase efficiency" can be realized.