550kV Dead tank SF6 circuit breaker

1. Their core difference is arc-extinguishing media: Vacuum breakers use high vacuum (10⁻⁴~10⁻⁶Pa) for insulation and arc extinction; SF₆ breakers rely on SF₆ gas, which adsorbs electrons well to quench arcs.
2. In voltage adaptation: Vacuum breakers fit medium-low voltages (10kV, 35kV; some up to 110kV), rarely 220kV+. SF₆ breakers suit high-ultra high voltages (110kV~1000kV), mainstream for ultra-high voltage grids.
3. For performance: Vacuum breakers extinguish arcs fast (<10ms), have 63kA~125kA breaking capacity, suit frequent use (e.g., power distribution) with long life (>10,000 cycles). SF₆ breakers excel in stable large/inductive current breaking but work less frequently, needing insulation recovery time post-extinction.
4. Compared to SF6 gas circuit breakers, vacuum circuit breakers can achieve zero greenhouse gas emissions and are more environmentally friendly because the arc extinguishing device does not contain any gas

During the normal operation and interruption processes of a circuit breaker, SF₆ gas can decompose, producing various decomposition products such as SF₄, S₂F₂, SOF₂, HF, and SO₂. These decomposition products are often corrosive, toxic, or irritating, and therefore require monitoring.If the concentration of these decomposition products exceeds certain limits, it may indicate abnormal discharges or other faults within the arc quenching chamber. Timely maintenance and handling are necessary to prevent further damage to the equipment and to safeguard personnel health.

The leakage rate of SF₆ gas must be controlled at an extremely low level, typically not exceeding 1% per year. SF₆ gas is a potent greenhouse gas, with a greenhouse effect 23,900 times that of carbon dioxide. If a leak occurs, it can not only cause environmental pollution but also lead to a decrease in the gas pressure within the arc quenching chamber, affecting the performance and reliability of the circuit breaker.

To monitor the leakage of SF₆ gas, gas leakage detection devices are typically installed on tank-type circuit breakers. These devices help to promptly identify any leaks so that appropriate measures can be taken to address the issue.