The traditional DC high voltage generator adopts open structure with large volume and weight

so it has to be disassembled for transportation and assembled for field test

leading to extra difficulty and time consumption. Although the high-stability DC high voltage generator with high frequency has much smaller volume and weight

it cannot achieve the voltage level of 1 200 kV at present. Therefore

this study adopted the closed gas insulation structure to design and develop a 1 200 kV compact DC high voltage generator

including optimization design of internal devices such as resistor and voltage-sharing silicon reactor

and electric field simulation of generator body. Its overall size was reduced by 30% and weight was reduced by 25%

compared with those of the traditional generator. The scheme of horizontal transportation and vertical use was adopted for the generator to greatly improve the efficiency of field operation. Third party testing for the DC high voltage generator was conducted in accordance with the national standards for gas insulation

and a leakage current test of the 1 000 kV arrester under 0.75 time of reference voltage was also conducted in Shanxi Jinzhong UHV substation. Both tests met the testing requirements. Therefore

the difficulty in conducting field test for whole UHV arrester is resolved successfully.