With the continuous expansion of 500 kV main grid

localized areas are experiencing excessive short-circuit capacity. The insertion of fault current limiter

consisting of fast switch in parallel with a current limiting reactor

into the transmission line is an effective way to address excessive short circuit capacity. It is therefore necessary to develop a fast switch for 500 kV fault current limiter. The fast switch adopts tank type

multi-break series structure. The fast opening and closing operation is achieved by the electromagnetic repulsion operating mechanism. The simulation design of the repulsive operating mechanism

shield structure

grading and temperature rise is carried out. The design is verified by such tests single break mechanical endurance

ground insulation

insulation between terminals and temperature rise. The results show that regarding the repulsive operating mechanism

the opening time of contact of vacuum interrupter is less than 1 ms

the maximum opening speed is 7.6 m/s

the maximum stress on the link rod is 120 kN

the peak of pulse currentis 9 688 A and the 3 000 times mechanical endurance test issucessfully passed. Regarding the shield structure

the electric field intensity is reduced by adjusting the three radii at the shield edge to curve it inward. The optimized field intensity is 16 kV/mm and the ground insulation test is sucessfully passed. In terms of grading

the grading capacitance of 6 000 pF for 6 vacuum arc interrupters in parallel is selected. At this time

the uneven voltage coefficient under lightning is 1.21

and the insulation test between terminals is sucessfully passed. In terms of temperature rise

the highest temperature point is at the position of the contact of the vacuum interrupter and the temperature rise is 52.5 K. Except the vacuum interrupter

the highest temperature is near the end surface of the stationary contact on top of the interrupter

and the temperature rise is 34 K. The temperature rise test value is close to that of simulation. The developed tank type fast switch meets relevant standards and operational requiremets at site.