Surface conductivity has been proven to be an ideal index for evaluating insulator pollution

since it contains comprehensive information of the pollution including composition

wetting degree

and distribution. Promoting the application of surface conductivity measurement requires relatively simple devices

hence we proposed a method that could measure the unit surface conductivity

and developed a corresponding measurement system. The system has a test chamber with controllable humidity and temperature inside

and it can measure the leakage current precisely

store the data in real time

and calculate the unit surface conductivity of insulator. Experimental results of both artificial pollution tests and natural pollution tests indicate a negative exponential relationship between the unit surface conductivity and flashover voltage of contaminated insulators. Being applied to site pollution severity tests

the proposed system can obtain the unit surface conductivity efficiently

and the predicted flashover voltage based on unit surface conductivity is close to its real value.