LW38-72.5KV Outdoor High-Voltage SF6 Circuit Breaker
LW38-72.5KV Outdoor High-Voltage SF6 Circuit Breaker is a three-phase AC SF6 circuit breaker designed for 72.5kV (66kV system) outdoor high-voltage power transmission and distribution applications. It uses SF6 gas as the arc-extinguishing and insulation medium, featuring reliable breaking performance, stable insulation capability, and excellent mechanical durability. The circuit breaker is widely used for transformer protection, transmission line switching, and power grid interconnection, providing safe and efficient operation in various outdoor environments.
Get a QuoteOverview
The LW38-72.5 is a three-phase AC 50Hz SF6 circuit breaker designed for outdoor high-voltage power transmission and distribution systems with a rated voltage of 72.5kV (suitable for 66kV systems). Utilizing SF6 gas as the arc-extinguishing and insulation medium, this circuit breaker provides reliable control and protection for power lines and transformers. It is especially suitable for regional power transmission and transformation applications requiring high breaking performance, excellent mechanical stability, and long-term operational reliability. The LW38-72.5 can be used as a primary protection circuit breaker or a power grid interconnection device.
Features
Advanced Arc Extinguishing Technology and Energy-Efficient Operation
The LW38-72.5 SF6 circuit breaker features an advanced self-energy arc-extinguishing system, with optional auxiliary pressure-blast technology available for specific configurations. During the interruption process, the energy generated by the arc is utilized to rapidly heat and expand the SF6 gas, generating a high-pressure airflow that effectively accelerates arc cooling and extinction.
By optimizing the interaction between thermal expansion and mechanical gas compression, the circuit breaker achieves fast and stable current interruption at zero crossing, with minimized arcing time and without current chopping. This effectively reduces transient overvoltage risks and improves the protection capability of connected power equipment.
The circuit breaker is equipped with a reliable CT20 spring operating mechanism, which provides high operating efficiency and reduced energy consumption. Compared with conventional pressure-blast circuit breakers, the operating energy demand is reduced by more than 30%, while mechanical vibration and operating noise are significantly improved.
With a fast-response operating mechanism, the opening time can be maintained within 55~65ms (DC operation), and the closing time is ≤100ms, meeting the requirements of modern power systems for rapid fault clearing and reliable protection.
High Electrical Performance and Long-Term Mechanical Reliability
Superior Short-Circuit Interruption Capability
Designed for demanding high-voltage power applications, the LW38-72.5 SF6 circuit breaker provides a rated short-circuit breaking current of 40kA. It is capable of performing 8 consecutive fault current interruptions without maintenance, ensuring stable operation under severe fault conditions.
The rated short-circuit making current reaches 100kA (peak value), providing strong closing capability during short-circuit faults. It is widely applicable to industrial power distribution networks, regional transmission systems, and substations with high fault current levels.
Durable Mechanical Structure
The LW38-72.5 adopts a single-break, three-pole linked structure together with a precision transmission mechanism. The optimized mechanical design enables a service life of up to 6,000 mechanical operations, ensuring long-term operational stability.
The extended mechanical endurance helps reduce maintenance frequency, improve equipment availability, and lower the overall lifecycle cost of power system operation.
Reliable SF6 Insulation System
The circuit breaker utilizes SF6 gas insulation technology with a rated gas pressure of 0.45MPa (gauge pressure at 20℃). The gas moisture content is controlled at ≤150ppm(v/v), ensuring excellent insulation reliability during long-term operation.
The equipment provides a rated lightning impulse withstand voltage of 200kV to ground and 220kV across the fracture. The power frequency withstand voltage reaches 140kV to ground and 160kV across the fracture, enabling dependable performance in complex electrical insulation environments.
Adaptability to Various Outdoor Operating Conditions
The LW38-72.5 outdoor SF6 circuit breaker is designed for reliable operation in challenging environmental conditions. The standard configuration supports an operating temperature range from -45℃ to +40℃ and withstands wind speeds up to 34m/s, making it suitable for applications in cold regions, dry areas, and other demanding outdoor environments.
The porcelain insulator design can be optimized with optional creepage distances of 25mm/kV or above, allowing the circuit breaker to meet pollution level III and higher requirements. This ensures stable insulation performance in industrial pollution zones, plateau areas, and other contaminated environments.
The standard version is suitable for installation at altitudes below 1,000 meters. For higher altitude applications, an enhanced version can be customized to maintain reliable insulation and switching performance under special geographic conditions.
Technical Data
| Item | Unit | Parameter | |
| Rated Voltage | kV | 72.5 | |
| Rated Current | A | 1600 / 2500 / 3150 | |
| Rated Frequence | Hz | 50 | |
| Rated Short-Circuit Breaking Current | kA | 40 | |
| Rated Short-Circuit Making Current (Peak) | 100 | ||
| Rated Short-Time Withstand Current (4s) | 40 | ||
| Rated Peak Withstand Current | 100 | ||
| Rated Out-of-Step Breaking Current | 10 | ||
| Rated Insulation Level | Lightning impulse (to ground) | kV | 200 |
| Lightning impulse (fracture) | 220 | ||
| Power frequency withstand voltage (to ground) | 140 | ||
| Power frequency withstand voltage (fracture) | 160 | ||
| SF6 Gas Parameters | Rated pressure (gauge pressure at 20℃) | Mpa | 0.45 |
| Gas replenishment pressure | 0.42 | ||
| PaLockout pressure | 0.4±0.01 | ||
| Annual gas leakage rate | % | ≤1 | |
| Moisture content | ppm(v/v) | ≤150 | |
| Operating Performance | Opening time | ms | 55-65DC / ≤60AC |
| Closing time | ≤100 | ||
| Close-open time | ≥120 | ||
| Rated operating sequence | / | Open—0.3s Close-Open—180s—Close-Open | |
| Mechanical Life | Times | ≥6000 | |
| Equipment Weight | kg | 800kg (without CT) / 1,000kg (with CT) | |
| SF6 Gas Filling Capacity | kg | 5 | |
Overall and mounting dimensions(mm)
Structural Design and Maintenance Advantages
Optimized Structure with High Reliability
The LW38-72.5 SF6 circuit breaker adopts a three-phase independent porcelain post structure with a single-break configuration. The three poles are mounted on a common base frame and mechanically synchronized through a reliable transmission linkage system, providing a compact layout, simplified structure, and reduced outdoor installation space.
The SF6 gas chambers of the three phases are interconnected through steel pipelines to maintain balanced gas pressure and stable insulation performance. The arc-extinguishing chamber integrates key components including fixed contacts, moving contacts, and arc nozzles. Through the optimized transmission mechanism inside the operating box, the moving contacts achieve precise vertical movement with high mechanical efficiency and reduced component wear.
According to application requirements, built-in current transformers (CT) can be integrated into the circuit breaker design for measurement and protection purposes. This integrated structure reduces the number of external components, improving overall system reliability and minimizing potential failure points.
Maintenance-Friendly Design for Long-Term Operation
Reliable SF6 Gas Monitoring and Management
The circuit breaker is equipped with an SF6 density monitor for continuous gas pressure supervision. When the gas pressure decreases to 0.42MPa, a gas replenishment warning is triggered. If the pressure further drops to 0.40MPa, the operating mechanism is automatically blocked to prevent insufficient insulation performance and reduced arc-extinguishing capability.
With an annual SF6 leakage rate of ≤1%, the equipment maintains a long gas service cycle, effectively reducing maintenance frequency and operation costs.
Internal Moisture and Decomposition Protection
A molecular sieve is installed inside the transmission box area to absorb moisture and low-fluoride decomposition products generated during SF6 operation. This helps reduce internal corrosion, maintain insulation reliability, and extend the service life of critical components.
Compatibility with Intelligent Substation Systems
The operating mechanism supports multiple AC and DC control voltage configurations, including closing coil options of AC220V, DC48V, DC110V, and DC220V. It can be integrated with bay control cabinets to achieve local and remote operation switching.
When combined with intelligent monitoring and protection systems, the LW38-72.5 enables condition monitoring and unattended substation operation, meeting the requirements of modern smart grid applications.
Typical Application Areas
66kV Regional Substations
As a primary switching and protection device in 66kV regional substations, the LW38-72.5 SF6 circuit breaker provides reliable interruption of short-circuit faults and operational control of transformer feeders and outgoing lines. It is suitable for key power transmission and distribution nodes in suburban and county-level power networks.
Industrial Power Distribution Systems
The circuit breaker meets the requirements of high-current and high-reliability industrial power systems, including applications in metallurgy, chemical processing, and large-scale manufacturing facilities. Its robust interruption capability and mechanical endurance allow reliable operation under frequent switching conditions and complex load variations.
Renewable Energy Grid Connection Systems
The LW38-72.5 is suitable for 66kV collector and step-up station outgoing circuits in wind power and photovoltaic projects. Its reliable fault interruption capability helps manage fluctuating renewable energy output and ensures stable connection between renewable power sources and the utility grid.
High-Altitude and Cold Climate Applications
With an operating temperature capability down to -45℃, the circuit breaker is suitable for cold and high-altitude regions. The optimized sealing system and operating mechanism design reduce the impact of low temperatures, ensuring stable switching performance during harsh winter conditions.
Applicable Standards and Quality Assurance
The LW38-72.5 SF6 circuit breaker complies with the requirements of GB1984 AC High-Voltage Circuit Breakers and the international standard IEC 56.
The product has successfully completed type tests and comprehensive factory inspections, verifying its electrical performance, mechanical endurance, insulation capability, and operational safety.
With compliance to widely recognized industry standards, the LW38-72.5 is suitable for mainstream 72.5kV power transmission and distribution systems in domestic and international markets.
