Thermal Breakdown Phenomenon in High Temperature CO2 and Air under DC-Voltage Application

P.C. Almiron, Y. Yokomizu, and T. Matsumura (Japan)


Hot gas, Gas Circuit Breakers, Thermal breakdown, CO2, Breakdown voltage


Firstly, we theoretically studied the development of the thermal breakdown in the hot CO2 and air applied with the dc-voltage. Under an electric field strength of 900 V/mm and a temperature of 3,000 K, the temperature of CO2 increased gradually with time and rose abruptly at 500 s. In the case of air, it took 5 s for the temperature to abruptly rise. In other words, hot CO2 withstands a larger electrical field than hot air without inducing thermal breakdown. Secondly, the thermal breakdown occurrence was experimentally investigated for the high temperature CO2 and air. Experimental results show that the thermal breakdown in hot air occurs at lower voltages than that in hot CO2. For an electrical conductance of 1 mS, the thermal breakdown voltage was found to be 70 V for hot CO2 while 50 V for hot air in our experiments.

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