SF6 for switch gear 1

[Bestboy]

I was in a medium course for the whole of last week and the trainer mentioned that SF6 filled-switchgear is by far the safest compared to vacuum and air filled. But he could not explain to us why the gas is so good in quenching a flash. I did not need a chemical-engineer-hectic-type-of-an-answer, just the basic.

 

[RalphChristie]

Here a actually quite a lot of info on this site (use the search engine on eng-tips.com) regarding SF6.

http://www.sayedsaad.com/substation/index_sf6.html

Gas properties of SF6
"Today there is no known dielectric and breaking agent combined better than SF6 gas"

http://www.panickker.net/article6.htm

Comparison between SF6 and Vacuum

Regards


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[itsmoked]

Has high thermal conductivity too (I think) which would help carry away the thermal energy required to keep an arc happy.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[bluemagic]

In some mediumvoltage switchgears SF6 gas only for insulation,they still use the vacuum interrupter to quech arc.

 

[dede61]

To itsmoked, SF6 has high thermal insulation capacity, it has been used in insulating double glas, also because it is a big molecule and therefore is easier to seal. If I'm not mistaken it was even used to fill car/truck tyres because of the reduced leaking possibility. Now all these applications are abandone due to the enviromental issues with SF6 gas.

 

[itsmoked]

dede61; I stand corrected.
Thanks!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[cuky2000]

For medium voltage applications SF6 or vacuum protective devices are close equivalent in term of performance, cost and applications.

The vacuum technology in the US by far is more popular than SF6 for MV application. Engineering preference in other part of the world favor the use of SF6.