The phase to phase and phase to ground distances in air to ensure the security of 35 kV switchgear bus are obtained through the rod-plane air gap experiment at the place below of 1 000 meters altitude.In fact

there exists differences between the structure of rod-plane air gap and switchgear bus

and in higher altitude

discharge in air becomes easy due to lower atmospheric pressure.In order to get the net safety distance in 35 kV switchgear at 2 000 meters altitude

switchgear bus structures are classified and the simulation experiment switchgear is designed in this paper.Power frequency voltage and impulse voltage tests are taken to the different structure in 2 000 meters altitude.The minimum distance without discharge

normally called net safety distance

is obtained through experiment in which applied voltage values are in accordance to standard.The results can be referred to switchgear design and manufacture.