Sulfur hexafluoride circuit breakers protect electrical and distribution systems by interrupting electric currents, when tripped by a . Instead of oil, air, or a vacuum, a sulfur hexafluoride circuit breaker uses (SF6) gas to cool and quench the arc on opening a circuit. Advantages over other media include lower operating noise and no emission.
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When was the first SF 6 circuit breaker made?
The first high-voltage SF 6 circuit breaker with a high short-circuit current capability was produced by Westinghouse in 1959. This circuit breaker in a grounded tank (called a dead tank), could interrupt 41.8 kA under 138 kV (10,000 MV·A) and 37.6 kA under 230 kV (15,000 MV·A).
Why are SF 6 circuit breakers so popular?
The achievement around 1983 of the first single-break 245 kV and the corresponding 420 kV to 550 kV and 800 kV, with respectively 2, 3, and 4 chambers per pole, led to the dominance of SF 6 circuit breakers in the complete range of high voltages. Several characteristics of SF 6 circuit breakers can explain their success:
How many kV can a SF 6 circuit breaker interrupt?
The first high-voltage SF 6 circuit breaker built in 1956 by Westinghouse, could interrupt 5 kA under 115 kV, but it had six interrupting chambers in series per pole.
How does SF 6 breaker work?
SF 6 gas is electronegative and has a strong tendency to absorb free electrons. The contacts of the breaker are opened in a high-pressure flow of sulfur hexafluoride gas, and an arc is struck between them. The gas captures the conducting free electrons in the arc to form relatively immobile negative ions.