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SF6 Extinguishing Characteristics And Function
Dec 07, 2017

    SF6 gas is colorless, odorless, non-toxic inert gas, with good insulation properties, and will not deteriorate. It is about 5 times the proportion of air. At standard atmospheric pressure, it is liquefied at -62 C. The insulation strength is greatly influenced by the electrode, 2 to 3 times the air in the uniform electric field, and the insulation strength of the transformer is equal to the transformer oil at 3 atmospheric pressure. At 12 atmospheric pressure, it is liquefied at 0 degrees. The physical properties of it.

The arc in the gas is a conduction phenomenon formed by molecular dissociation, and the main heat free mode is in the arc discharge channel. When the temperature of the gas is above 4000-6000K, the phenomenon of heat free conduction begins to occur. The electrical conductivity of SF6 and air with the variation of temperature difference is small, the 4000K was not free, but in the metal vapor arc electrode in the presence of free hot starting temperature of actual will be the first to about 3000K, so the conductive lower limit temperature switching arc 3000K in general, so the conductive lower limit temperature switching arc in general near 3000.

The extinction process of arc is the combination of arc gap free products (ions and electrons), which eliminates the gap, and makes the gap return to the state of insulating medium.

Arc extinguishing action

The compound effect of 1:SF6

Some high temperature arc products in SF6 may be combined at the moment of arc suppression, and the dielectric strength of the remaining arc column can be quickly restored to a certain degree of initial stage.

The cooling effect of 2:SF6

SF6 is a good cooling medium, and its cooling effect is good, it can reduce the arc temperature effectively, which is beneficial to the extinguishing of the arc.

3:SF6 has the ability to adsorb electrons

A can reduce electron density, reduce conductance, and cause the arc to die out. Because B SF6- migration speed is slower than that of electrons, SF- and SF+ can easily synthesize SF6, which is also conducive to the extinction of electric arc.