SF₆ circuit breakers Workflow breakdown
SF₆ automatic isolating switches utilise the high dielectric strength of the gas to interrupt the current.
When the contacts open, an arc is formed, and the high temperature of the arc causes the SF₆ molecules to decompose into oxygen and fluorine atoms.The fluorine atoms rapidly capture free electrons, forming heavy negative ions that move slowly, which greatly reduces the conductivity of the gap.
At the same time, the breaker is equipped with a puffer or self‑blast arc‑blowing mechanism that produces a high‑speed gas flow during the opening operation, forcibly sweeping away and cooling the charged particles in the arc. This allows the dielectric strength across the gap to recover quickly at the instant of current zero, thereby successfully quenching the arc.
vacuum circuit breakers Workflow breakdown
Unlike SF₆ breakers, vacuum circuit breakers do not rely on "gas blowing" at all.
The pressure inside their interrupter chamber is extremely low (about 10⁻² to 10⁻⁴ Pa), approaching a true vacuum. When the contacts part, the arc is formed solely from metal vapour. Because the vacuum medium has an extremely high dielectric recovery speed (up to tens of kV/μs), and the vapour particles rapidly diffuse outward and condense on the arc shield, the dielectric strength across the gap recovers instantaneously after current zero, and the arc extinguishes naturally.
The entire process involves no gas flow; instead, it relies on the vacuum's own excellent insulation properties and diffusion capability.
Summarize
Although the arc‑quenching mechanisms of the two types of breakers are fundamentally different, both can effectively interrupt short‑circuit currents.
Vacuum circuit breakers, with no risk of gas leakage and easy maintenance, are widely used in medium‑voltage distribution networks, while SF₆ breakers, owing to their high interrupting capacity, are mostly employed in high‑voltage and extra‑high‑voltage transmission systems.
Against the backdrop of the "dual carbon" goals, environmentally friendly vacuum circuit breakers are gradually replacing some SF₆ equipment, becoming an important choice for green power grids.
Shaanxi West Power Tongzhong Electrical Co., Ltd.
Our address
Nanpo Village, Chencang Avenue Jintai District Baoji City, Shaanxi Province, China.
Phone Number
+86 18091766017(WhatsApp/Wechat/facebook)
