1. Introduction to Plasma Processing SF 6 Circuit Breaker Student: Hosny, Ahmed A. Instructor: Prof. Kasra Etemadi

2. Outline …  Introduction  Why SF 6 Circuit Breakers?  Advantages/Disadvantages  How does it work?  Applications  Summary  References

3. Introduction  What Kind of Plasma do we deal with?

4. Introduction  What is Circuit Breakers (CBs)?  CB is one of the most essential safety mechanisms in electric networks.  Interrupt short circuit currents (~ 60kA, low pf ~ 0.1).  Fault clearance time is very important for power system stability and avoid equipment damage for itself and the rest of the network.

5. Introduction (Cont.)  CBs types  Oil circuit breakers  Vacuum circuit breakers  Magnetic Air Circuit Breakers  Air-blast circuit breakers  SF 6 circuit breakers Figure 2 SF6 partial interrupter unit.

6. Advantages/Disadvantages?  SF 6 has a dielectric strength of about two to three times that of air.  It is nontoxic.  It is nonflammable.  It is noncorrosive; it doesn’t react with other materials because it is inert gas. However, when it is heated to 5000C it decomposes and its decomposition products react with other materials.  It exhibits excellent properties for arc quenching. So, it used as an interrupting medium in circuit breakers instead of air or oil.

7. Applications  Gas-insulated switchgear (GIS) Figure 3 GIS layout