SF6 Circuit breaker
SF6 circuit breaker is widely used in power systems of 72.5kV and above. The following are its core points:
1. Basic working principle
Arc extinguishing principle:
SF6 gas decomposes into low-conductivity plasma under high arc temperature, which can quickly absorb arc energy and achieve current interruption (arc extinguishing time is only 10~20 milliseconds).
Insulation principle:
SF6 has a dielectric strength three times that of air and can maintain stable insulation performance under high voltage.
2. Core features
1) Advantages
✅ Ultra-high arc extinguishing capability (can break short-circuit current of more than 63kA)
✅ Compact structure (suitable for GIS gas insulated switchgear)
3. Typical structure
Arc extinguishing chamber: SF6 gas sealed cavity, containing moving and static contacts.
Operating mechanism: Spring/hydraulic mechanism drives the contacts to open and close.
4. Step-by-step analysis of the working process
Take the compressed air SF6 circuit breaker as an example (the most common type):
Step Action Description Physical Process
|
Process |
Aection description |
physical process |
|
① Closed state |
The moving and fixed contacts are in close contact, and the current is normally conducted. |
The SF6 gas maintains a high pressure (0.4~0.6MPa) to ensure insulation. |
|
② Opening trigger |
The operating mechanism (spring/hydraulic) pulls the insulating pull rod, and the contacts begin to separate. |
Mechanical energy is converted into kinetic energy of contact movement. |
|
③ Arc generation |
At the moment of contact separation, the current is concentrated at the last contact point, generating a high-temperature arc (5000~15000K) |
SF6 gas is heated by the arc and decomposed into conductive plasma. |
|
④ Compressed air arc extinguishing |
The moving contact drives the compressed air piston to compress the SF6 gas, and the high-pressure airflow blows longitudinally to the arc. |
High-speed SF6 airflow cools the arc, takes away the charged particles, and accelerates plasma recombination(→SF6 regeneration) |
|
⑤ Current zero crossing arc extinguishing |
When the AC current naturally crosses zero, the strong electronegativity of SF6 absorbs free electrons and blocks. |
the arc from reigniting Dielectric recovery strength > The system restores voltage and the arc is completely extinguished. |
|
⑥ Complete opening |
The contacts are completely separated, and the break is filled with high-voltage SF6 gas to form a reliable insulation. |
The insulation strength of the break is restored to the rated value |
5. Application scenarios
High-voltage substation (110kV~1000kV)
Wind power/photovoltaic booster station (collection system protection)
Industrial high-current power distribution (such as steel mills, electrolytic aluminum)
6. Key selection parameters
1. Rated voltage (such as 126kV, 252kV)
2. Short-circuit breaking capacity (such as 31.5kA, 40kA)
3. Gas pressure range (usually 0.4~0.6MPa)
4. Mechanical life (≥10,000 times)
LW25-126 Outdoor high voltage procelain SF6 Circuit breaker
LW25-126 outdoor high voltage porcelain SF6 circuit breaker produced by Shaanxi West Power Tongzhong Electrical Co., Ltd. is an outdoor, three-phase AC 50Hz high voltage electrical equipment. It is primarily used to protect transmission and distribution lines and can also be used as a tie breaker. This circuit breaker features a three-phase mounted on one frame, with no provision for single-phase operation.
LW25-126 outdoor high voltage porcelain SF6 circuit breaker has many advantages:
1.Superior Breaking Capability
When interrupting magnetizing current, the overvoltage is less than twice the operating voltage. Additionally, when interrupting charging current, there is no re-striking or re-ignition occurs.
2.Reliable Insulation
The properties of SF6 gas remain stable over time, protecting the insulating and conductive components from oxidation and ensuring stable temperature operation.
3.Minimal Maintenance:
The circuit breaker features a modular structure with advanced technology, reduced components, and excellent mechanical performance, and requires almost no maintenance.
contact us
Please feel free to contact us as per following information:
Email: xdtz04@westpowerelectric.com
Website: https://www.xdtzelectrical.com/
Tel:+86 917 3661109
Mobilephone(whatsapp ): +86 18091765882
