The Development Of Electrical Test System For Insulation Gases At Ambient And Low Temperature

Because of the high liquidus temperature and extremely high Global Warming Potential （GWP） index, the application of SF₆ is being restricted gradually. In order to solve the superconducting transmission and cryogenic insulation problems in extremely cold area of circuit breaker and to reduce the use of SF₆, it is necessary to research electrical characteristics of the substitutes for SF₆ and their mixtures at ambient and low temperature. An electrical test system for insulation gases at ambient and low temperature is developed in this paper, the main contributions are as follows:1. The structure and cryogenic system of the electrical test system has been designed, which can provide relatively stable platform of low temperature and sealing for the test of gas insulation. The results show that the negative pressure of the system can be kept at below 0.1 Pa and the positive pressure can be sealed at 0.8MPa. Using liquid nitrogen as the refrigerant, the temperature of the gases in the gas test chamber can be cooled below 120K. In addition, the distance of the electrode can be adjusted in sealing condition.2. The temperature monitoring and control system, which can accurately monitor temperature of 4 positions in real time, including high voltage electrode and the upper end, the middle and the bottom of the gas test chamber. The system can also store multiple data for later processing. The temperature-controlled precision of the test gas is plus or minus 2K, and the time of temperature-maintain is not less than 30 minutes.3. Using the developed electrical test system to carry out the research of electrical performance of gases under ambient and low temperature ranges respectively. SF₆/N₂ mixtures have been chosen in the research at ambient temperature to carry out the AC breakdown test, changing the pressure of the gases and the proportion of SF₆, while N₂ has been used for the low temperature research, changing the pressure and temperature.The developed system can be effectively applied in gas electrical performance test at both ambient and low temperature, helping to carry out the researches of electrical performance of a variety of insulating gases, and the results has important guiding significance to effectively solve the superconducting transmission and cryogenic insulation problems in extremely cold area of circuit breakers and to reduce the use of SF₆, building a green, environmentally friendly and low-consumption electric power system.