Air insulated disconnector needs to possess a definite capability to switch small capacitive current. However

it has no arc interruption function

which will produce serious arc during the opening process

the capacitive voltage at the power side and arc current can generate impulse waves and threaten insulation of equipment. The high resolution camera is adopted to film the arc during the opening process of air insulated disconnector

finding that the arc is not interrupted

which is different from the arc characteristic of disconnector for gas insulated metal enclosed switchgear（GIS）. Based on this phenomena

the traditional double exponential high-frequency arc resistance model is improved in

this paper. It is thought that the dielectric strength of the air gap has not been completely restored before arc interruption during the opening period

the corresponding arc resistance doesn’t reach to 10

12

Ω. The circuit for switching small capacitive current by the disconnector is set up in ATP-EMTP. It is found by analysis that the trend of simulation results is basically consistent with that of test results. The set up of the model has certain theoretical guidance for the research of switching small capacitive current by air insulated disconnector.