In 10kV power distribution systems, two types of circuit breakers are commonly used: vacuum circuit breaker and SF6 circuit breaker.
These two types of circuit breakers differ in their structure, operating principles, and purpose, but both are important protection and control devices in power distribution systems. Vacuum circuit breakers utilize a vacuum bubble to extinguish arcs, resulting in a low current cutoff value. In vacuum circuit breakers, the contacts are sealed in a vacuum tube, effectively suppressing arc formation and ensuring the circuit breaker's performance and lifespan.
SF6 circuit breakers utilize SF6 gas for arc extinguishing and insulation, boasting a high current cutoff value. SF6 gas possesses excellent insulation and arc extinguishing properties, enabling arc extinguishing under high voltage and high current conditions. Here, we introduce these two types of circuit breakers. We hope this will provide a deeper understanding of these two types for those in the electrical industry.
Vacuum circuit breaker
The contacts of a vacuum circuit breaker interrupt the circuit within a highly vacuumed arc-extinguishing chamber. The insulating and arc-extinguishing medium used is a highly vacuumed air. Ionizable materials are essentially absent from the arc-extinguishing chamber. Under all circumstances, when the contacts separate, the arc path between them consists solely of the metal vapor of the contact material.
The advantages of vacuum circuit breakers include a small contact gap and fast actuation; short arcing time and rapid arc extinguishing; small size, light weight, fire and explosion resistance, and suitability for frequent operation.
Representative products include ABB's VD4 series and Schneider's HVX12 series vacuum circuit breakers.
SF6 Circuit breaker
Sulfur hexafluoride circuit breakers use sulfur hexafluoride gas as both an insulating and arc-extinguishing medium. Sulfur hexafluoride has excellent insulation and arc-extinguishing capabilities, with insulation approximately 2.5 to 3 times greater than air. Most SF6 circuit breakers utilize an arc-extinguishing principle based on a combination of thermal expansion and compressed gas blowing. This technology has been widely and maturely applied in high-voltage switchgear. It offers smooth interruption characteristics, preventing current chokes and thus preventing switching overvoltages, which can reduce the life of capacitor banks.
After a SF6 circuit breaker is opened, its contacts experience minimal burnout, extending maintenance cycles and making it suitable for frequent operation. Representative products include ABB's HD4 series SF6 gas circuit breakers and Schneider's FP12 series SF6 gas circuit breakers.
Selection of vacuum circuit breakers and SF6 circuit breakers
When selecting a circuit breaker, it's important to consider the specific requirements and operating conditions of the distribution system. For example, vacuum circuit breakers can be chosen for applications requiring frequent operation and low current cutoff values; SF6 circuit breakers can be chosen for applications requiring high current interruption and high current cutoff values.
In summary
Both vacuum circuit breaker and SF6 circuit breaker are commonly used in 10kV distribution systems. Choosing the right type based on specific requirements ensures safe and stable operation of the distribution system.
Shaanxi West Power Tongzhong Electrical Co., Ltd.
Our address
Nanpo Village, Chencang Avenue Jintai District Baoji City, Shaanxi Province, China.
Phone Number
+86 18091767067(WhatsApp/Wechat/Telegram)
