[sijijosek]

What happens when a SF6 Circuit Breaker is operated (closed or opened ) without any SF6 gas inside it ?

[KISS]

From here, Sulfur hexafluoride, SF6, Physical properties, safety, MSDS, enthalpy, material compatibility, gas liquid equilibrium, density, viscosity, flammability, transport properties , it's an insulating dialectric.

From here: SF6 Gas Properties

It's used both as an isulator and for extinguishing an electric arc.

From here, I'll let you use the material between your ears to draw any other conclusions.

[Newton1Law]

This question could use a little more information from "sijijosek", such as, the operation is on a fully energized circuit breaker or the operation is on a fully deenergized cirucit breaker. If the first case is what is planned, the circuit breaker will most likely fail electrically and substain damage both electrically and mechanically. If the second case is planned, some SF-6 circuit breakers may be operated without sustaining mechanical damage, but most will be damaged without the SF-6 gas to act as a buffer.

[sajithstya]

If it is in the fault condition or in loaded condition it will be flash

[singhh]

Further to elaborate this question as I understood is "what impact would be if SF6 circuit breaker will operate without SF6 gas ?"

Ans:- In Practical condition there are always some protections for monitoring the gas pressure e.g. In 220 kV SF6 breaker 6-7 bar is the normal working pressure and if it reaches up to 5 bar then there will an alarm for "gas pressure low" and further to this if it reduces below 4.5 bar the breaker will trip & get locked out.

As SF6 gas acts as arc quenching & insulating medium. So during operation without SF6 gas, due to arcing phenomenon while operating the moving contact there maximum chances of failure of thermal insulation of breaker which will result into flash over.
Hope I have answered what best I could.
Thanks
Harpreet Singh

[cupidbraveheart]

The answers before was very helpful its just if the pressure in the cb become below 5 bar in 220 kv it will block or trip in case of block u have to un load that cb and then switch it of