Effect of Magnetic Field Strength and Admixture Gas on Current Interrupting Capability of a CO₂ Rotary-Arc Type of Load-Break Switch

Abstract

Gas load-break switches adopting SF 6 as quenching media have been used in power-distribution systems. However, SF 6 is a greenhouse gas and thus it is desirous to use an environmentally benign gas as the quenching medium. On the basis of the previous research results, the CO 2 has been found to be candidate as the alternative quenching-gas for the load-break switches.Some of the load-break switches employ arc-extinguishing method called a rotary-arc type. This type of load-break switch has a ring-electrode and an interrupting arc runs on the inner surface of the ring electrode, owing to application of magnetic flux. This type of load-break switch is considered to have various factors affecting the interrupting capability: (a) material of the ring electrode; (b) strength of magnetic flux; (c) admixture of other gas to CO 2 and (d) gas pressure.Until now, we have investigated the effect of the above item (a) on the arc behavior and on the interrupting capability. As the next stage, the first purpose of the present research is related to the item (b), being to measure how great rate an arc rotational velocity and a current-interrupting capability increases with the strength of the magnetic flux. The second aim of this research is related to the item (c), being to find out effect of CO 2 mixtures on the currentinterrupting capability.

SF6 Alternatifi Yalıtkan Gazların Çevresel ve Fizyokimyasal Özellikleri

“…Stable molecules and noble gases in the atmosphere are often used as pure or gas mixtures in search of an alternative to SF 6 due to their almost no greenhouse effects, they can be used in cold climates without risk of liquefaction independent of pressure and low costs [23][24][25]. The relative dielectric coefficient of dry air, N 2 , N 2 O, CO 2 , O 2 , H 2 , Ar, He and Ne gases, which are frequently used in the literature among non-synthetic gases, varies between 0.37-0.40, 0.34-0.43, 0.44-0.50, 0.33-0.37, 0.20-0.22, 0.04-0.10, 0.02-0.06 and 0.01-0.02 ranges, respectively, see Table 1.…”

“…This feature can also be improved by applying a magnetic field in the perpendicular direction to the electric field that causes the breakdown [23,26]. Dry air, N 2 and CO 2 insulating medium switching and Gas Isolated System (GIS) designs are used by important manufacturers in the industry as transmission and distribution system equipment [2,4,25,27]. In applications where these gases are used in GIS and circuit breakers, important technical parameters such as rated voltage, rated normal current, short circuit breaking current and rated filling pressure range between 24-175 kV, 800-3150 A, 16-40 kA and 1.3-7.7 bar, respectively [4].…”