Product Introduction
The LW8(A)-40.5 outdoor AC SF6 circuit breaker is a three-phase AC 50 Hz outdoor high-voltage electrical device that uses SF6 gas as both the arc-extinguishing and insulating medium. It adopts a compressed air arc-extinguishing structure, providing strong breaking capacity. It is widely used in power systems with a rated voltage of 40.5 kV for switching rated currents and short-circuit currents in substations and power plants. It can also be used as a link circuit breaker and for switching capacitor banks. The internal current transformers are used for measurement and protection, making this breaker an ideal product for modernization and upgrades.
Structural Features
The circuit breaker features a compact, floor-mounted, outdoor tank-type structure equipped with a CT14 spring operating mechanism. The mechanism is integrated with the main body, ensuring simple installation, easy commissioning, and reliable operation, making it suitable for frequent operations. Its lifespan exceeds 3,000 operations.
It adopts a compressed air arc-extinguishing structure with strong breaking capability, capable of interrupting a 40 kA fault current up to 12 times, setting a domestic record. The sealing performance is highly reliable, using imported sealing gaskets. The dynamic seal features a “Y”-shaped sealing ring with a spring pressure compensation structure.
The secondary wiring board for the current transformer is supplied by a joint venture, ensuring an annual leakage rate of less than 0.5%. The internal current transformers use microcrystalline alloy materials with high magnetic permeability, achieving an accuracy class of 0.2 or 0.2s. Based on user requirements, up to 12 current transformers can be included. The circuit breaker is capable of no-reignition operation in no-load long lines up to 50 km.
Main Technical Parameters of Circuit Breaker
| No. | Parameter Name | Unit | Parameter Value |
| 1 | Rated voltage | kV | 40.5 |
| 2 | Rated current | A | 1600 / 2000 |
| 3 | Rated insulation level | kV | 95 (Grounded) / 185 (Contact gap) |
| 4 | Rated short-circuit breaking current | kA | 25 / 31.5 |
| 5 | Rated out-of-step breaking current | kA | 7.9 / 10 |
| 6 | Different-phase ground fault breaking current | kA | 27.4 / 34.8 |
| 7 | Rated breaking current of single capacitor bank | A | 400 |
| 8 | Rated operating sequence | – | O—0.3s—CO—180s—CO* |
| 9 | SF6 gas rated pressure (20℃ gauge pressure) | MPa | 0.45 |
| 10 | Opening time (rated voltage) | ms | 30 ≤ t ≤ 40 |
| 11 | Closing time (rated voltage) | ms | 60 ≤ t ≤ 80 |
| 12 | Rated short-circuit making current (peak) | kA | 63 / 80 |
| 13 | Rated short circuit duration | s | 4 |
| 14 | Rated short-time withstand current | kA | 25 / 31.5 |
| 15 | Rated peak withstand current | kA | 63 / 80 |
| 16 | Mechanical life test | Times | 10,000 |
| 17 | Accumulated breaking times (31.5kA/40kA short-circuit) | Times | 20 |
| 18 | Rated current cumulative breaking times | Times | 2000 |
| 19 | SF6 gas annual leakage rate | % | ≤0.5 |
| 20 | SF6 gas trace moisture content | ppm (V/V) | ≤150×10⁻⁶ |
| 21 | External insulation leakage specific distance | mm/kV | ≥25 / ≥31** |
| 22 | Circuit breaker weight | kg | 1000 |
