To meet the requirements of large capacity synthesis test for EHV switching equipment

it is necessary todevelop a 1 200 k V high-voltage controllable ignition device. The manufacturing difficulty

production period andcost will be greatly reduced if the ignition device adopts the three-ball and double-gap structure. In order to verify thefeasibility of the structure

the electrical field distribution in the device is simulated and analyzed. Simulation resultsshow that the three-ball and double-gap structure is beneficial to more uniform distribution of the electrical field. Inthe rated working condition

the maximum electrical field strength in the gaps is 1.747 k V/mm when the ball diameteris 1 500 mm and the gap distance is 500 mm

which meets the insulation requirement

and the safety factor is higherthan 1.5. In addition

the influence of gap distance on the electrical field distribution is reflected in the variation of dis-tributed capacitance

and the gap distance on high voltage side plays a more significant role in the potential distribution.