The LW38-40.5kV Outdoor SF6 Circuit Breaker leverages the unique physical properties of sulfur hexafluoride (SF6) gas to achieve superior arc extinction and insulation performance. As both the arc-quenching and insulating medium, SF6 enables this breaker to deliver reliable protection for 40.5kV transmission and distribution systems, particularly in applications demanding high breaking capacity and fast response times.
The arc extinction process in the LW38 utilizes the exceptional electronegativity of SF6 gas. When an arc forms between the separating contacts, the SF6 molecules capture free electrons, forming heavy negative ions that rapidly recombine. This unique mechanism quenches the arc within milliseconds, achieving opening times ≤0.06s and full breaking time ≤0.078s. This fast interruption minimizes fault energy and reduces stress on downstream equipment.
SF6's dielectric strength is approximately 2.5 times that of air at the same pressure, allowing for a compact interrupter design while maintaining high insulation margins. The LW38 achieves a lightning impulse withstand voltage of 185/215 kV and a power frequency withstand voltage of 95/119 kV, ensuring reliable operation even under transient overvoltage conditions. The sealed SF6 chamber maintains consistent dielectric performance regardless of external atmospheric conditions, a critical advantage for outdoor installations in polluted or humid environments.
The breaker's design includes precise gas management features. It operates at a rated SF6 pressure of 0.45 MPa (gauge at 20°C) , with defined alarm pressure of 0.42 MPa and lockout pressure of 0.4 MPa. The leakage rate ≤1%/year ensures long-term reliability with minimal gas replenishment. For high-altitude applications up to 3000m, the breaker's insulation level can be adjusted to compensate for reduced air density, maintaining full performance where standard equipment would derate.
Therefore, the LW38's SF6 technology delivers the high-speed interruption and dielectric robustness required for critical outdoor transmission applications. Putai also supports customization and the supply of related medium-voltage accessories to meet system integration needs. For detailed technical consultation on SF6 breaker application, contact our engineering team.
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