Experimental Study on Performance of SF₆+N₂Mixed Gas Insulation

Abstract

Abstract. This paper designed and constructed a 126kV GIS partial discharge test platform, performed frequency breakdown tests and lighting impulse tests at temperature of -30~20 to SF 6 /N 2 gas mixture. The present experiment studied frequency breakdown tests in different temperatue and slightly inhomogeneous electric field, obtained change in frequency breakdown voltage as a function of temperature; Analysed positive and negative lightning impluse test in gas mixture, in which SF 6 had a propotion of 30%~60%, in different temperature. Results indicated 50% probability breakdown voltage variation in positive lightning impluse tests, and in a low temperature environment, the breakdown voltage increased at negative lightning impulse, the polarity effects varied with condition of pure SF 6 gas. The experimental results showed implement of SF 6 /N 2 mixed gas with 30% SF 6 supersedespure SF 6 gas, could effectively reduce the consume of SF 6 , and remit greenhouse efect.

SF6 Alternatifi Yalıtkan Gazların Çevresel ve Fizyokimyasal Özellikleri

“…Owing to these properties, the breakdown voltage is three times higher compared to air at the unit distance provided that the product of the pressure and electrode gap remains constant, approximately 89 kV/cm [8]. SF 6 gas is used in almost 80% of gas-insulated applications in transmission and distribution systems such as circuit breakers, disconnectors, busbars and transformers [9]. In addition to this extensive use in power systems, it also has a wide range of industrial uses such as laser and semiconductor technology, plasma physics, magnesium and aluminum casting [10][11].…”

“…With the use in the power system industry, the size of switching elements such as circuit breakers and sectionalizers is reduced, the areas required for substations are reduced and supply processes such as transportation and installation are simplified [12]. In addition to these advantages of SF 6 , its major disadvantages can be listed as follows,  Disruption of discharge characteristics for high pressure and wide electrode gaps in nonhomogeneous electric field configurations [9],  Partial liquefaction depending on the high pressure in cold climatic conditions [9],  The occurrence of corrosive and toxic decomposition products as a result of partial discharge and breakdown mechanisms [13,14],  Since it is a synthetic gas, its relatively high cost [9], and  As it is an important greenhouse gas, its use causes important environmental problems [15]. Global Warming Potential (GWP) value, which is one of the greenhouse gas indicators, is 23.500 times of CO 2 for 100-year period [16].…”