Why SF6 gas are used in Sf6 breakers ?

Why SF6 gas are used in Sf6 breakers ?

 

WordSF6 or greenhouse emission gas molecules area unit combined by one sulfur and 6 gas atoms. This gas was 1st complete within the year of 1900 within the laboratories of the Faculte DE Pharmacie DE, in Paris.

In the year of 1937, General Electrical Company 1st complete that SF6 gas i.e. greenhouse emission gas is used as insulation.

After Second war, i.e. within the middle of twentieth century, quality of mistreatment greenhouse emission gas as AN insulation in electrical system was rising terriblyquickly.

Allied Chemical Corporation and Pennsalt were the primary yank industries, WHO began to supply this gas commercially in 1948. throughout 1960, mistreatment of greenhouse emission gas in high voltage switchgear became well-liked. because the demand of this gas was increasing several makers in Europe and America started manufacturing SF6 gas in massive scale, throughout that point.

At the start fluoride gas solely used for insulating purpose within the electrical system. however shortly it had been complete that this gas has tremendous arc extinctionproperty. Hence, this gas conjointly began to be utilized in electrical fuse as arc extinction medium.

World’s 1st SF6 gas insulated sub-station was established in Paris within the year of 1966. fluoride medium voltage circuit breakers embarked on market from 1971.

Producing of greenhouse emission Gas

SF6 or greenhouse emission gas commercially is factory-made by reaction of gas (obtained by electrolysis) with sulfur.

During method of manufacturing of this gas, different by merchandise like SF4, SF2, S2F2, S2F10 are created in little percentages. Not solely these byproducts impurities like air, moisture, carbon dioxide are gift within the gas, throughout production. of these byproducts and impurities area unit filtered at completely different stages of purification to induce pure and refine final product.

Chemical Properties of fluoride Gas

For examine chemical properties of fluoride gas, we have a tendency to 1st introduce structure of this molecule. during this gas, molecule, one sulphur atom is enclosed by six gas atoms.

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sulfur atomfluorine atom

The sulfur has number of sixteen. That means, it's two electrons in 1st energy state, eight electrons in second energy state and rest vi electrons in third energy state. Electronic configuration of sulphur atom is two, 8, 6 i.e. 1S2 2S2 2P6 3S2 3P4.

The atomic number {9|chemical element|element|gas|halogen} atom has number 9. The electronic configuration of gas is 1S2 2S2 2P5.

Each sulphur atom in SF6 molecule creates bond with vi gas atoms. during this method sulfur atom gets total vi valence bonds, i.e. vi combine of electrons at its outer shell, and every flourine atom gets eight electrons in its outer most shell.

N. B. : Here we will observe that, in greenhouse emission external shell of sulphur atom has twelve electrons rather than eight electrons. which means here sulfur doesn'tconform general positional representation system rule of atomic structure that states that, a stable atom needs eight electrons at its outmost shell. this can be not ANexceptional case. Some parts in third amount and below will kind compound that exceed eight electrons in its outer most shell.

The molecular structure of this gas is shown below,

molcular structure

In this method greenhouse emission absolutely satisfy stable structural condition. The effective radius of AN fluoride molecule is two.385 A. This exceptional electronic configuration and structure of this gas create SF6 very stable. The gas is stable with none decomposition in its molecular structure up to 500oC. it's extremely non ignitible. binary compound and Cl cannot react with this gas. It conjointly doesn't react with acid.

The SF6 gas is one in every of the heaviest gases. Density of this gas at 20oC at one gas pressure, is about 6.139 kg/m3 that is regarding five times on top of air at same conditions. relative molecular mass of this gas is 146.06.

The variation of pressure with temperature is linear for greenhouse emission and it's little among the service temperature, i.e. from - twenty five to + 50oC.

The meter heat of this gas is additionally high. it's around three.7 times quite that of air which is why this gas has conjointly tremendous cooling impact in electrical instrumentation. The thermal physical phenomenon of this gas isn't terribly high it's even below air. Still it's quite appropriate for cooling impact in electrical fuse. it's as a result of, throughout dissociation of greenhouse emission molecules round the spark, these molecules absorb high quantity of warmth. This heat is then free once the molecules reform at the edge of the arc. This method helps to transfer heat from hot season to chill season terribly quickly.

That is why; this gas has wonderful cooling impact at hot temperature though the thermal physical phenomenon of SF6 isn't terribly high.

Electrical Properties of SF6 Gas

SF6 gas is extremely negative. thanks to high negativity, it absorbs free electrons that created thanks to arcing between contacts of electrical fuse. Combination of free electrons with molecules produces significant and large ions, that have terribly low quality. thanks to absorption of free electrons and low quality of ions fluoride has terribly wonderful insulator property. insulator strength of greenhouse emission gas is regarding two.5 times quite that of air.press theme for your adult site. In this by adding video importor you can use the