Product Introduction
The LW36-126T High Voltage AC SF6 Tank Circuit Breaker integrates the circuit breaker and current transformer into a single unit. The arc-extinguishing chamber is horizontally mounted inside a grounded aluminum alloy housing and is paired with a CT26-type spring operating mechanism. The design features fewer components, a simple and compact layout, and a robust, durable structure, meeting the requirements for oil-free switches. With excellent mechanical properties and high reliability, all critical components are processed using CNC machining centers. The bearings used are imported international brands (e.g., IKO, INA, SKF). The mechanical life can reach up to 10,000 operations.
This circuit breaker is suitable for outdoor high-voltage switchgear in three-phase 50Hz AC systems and is used for control and protection in 72.5 (126) kV power transmission and distribution systems. It can also be used for circuit breaker connections and for switching capacitor banks.
Structural Features
The circuit breaker uses a three-phase porcelain pillar single-break structure, with a spring-operated mechanism centrally arranged and linked across the three phases, giving it an elegant and compact appearance. SF6 gas serves as both the insulating and arc-quenching medium. During operation, the three poles of the circuit breaker are interconnected with SF6 gas, and a pointer-type density relay monitors the pressure and density of the gas.
Thanks to the use of the self-energy arc-extinguishing principle and optimization of the breaker’s mechanical system design, mechanical efficiency is greatly improved, reducing operating power to a minimum. The breaker has excellent interrupting performance and a long electrical life.
The installation base and support frame are made from high-quality steel plates, with the surface treated using hot-dip galvanizing. All exposed fasteners are made from high-strength materials, with either hot-dip galvanizing or stainless steel components. The mechanism box is made from stainless steel, providing excellent corrosion resistance and high mechanical reliability for frequent operation.
With the inherent high insulating strength of SF6 gas and optimal contact movement, the breaker is capable of interrupting capacitive currents without re-ignition. The external insulation is designed with a large creepage distance (>31mm/kV), ensuring excellent resistance to contamination, allowing it to operate safely in harsh environments.
The breaker also has a strong current-carrying capacity: under a current of 1.2 times the rated value (3150A × 1.2 = 3780A), temperature rise tests show a considerable safety margin. The product’s overall appearance is compact, making on-site installation and commissioning easy with minimal maintenance required.
Main Technical Parameters of Circuit Breaker
| No. | Parameter Name | Unit | Parameter Value |
| 1 | Rated voltage | kV | 126 |
| 2 | Rated power frequency withstand voltage (1min) | ||
| – Grounded | kV | K – 230 | |
| – Contact gap | kV | K – 265 | |
| 3 | Rated lightning impulse withstand voltage | ||
| – Grounded | kV | K – 550 | |
| – Contact gap | kV | K – 630 | |
| 4 | Power frequency withstand voltage of SF6 gas at zero gauge pressure (5min) | Hz | K – 95 |
| 5 | Rated frequency | Hz | 50 |
| 6 | Rated current | A | 3150 |
| 7 | First pole to clear factor | – | 1.5 |
| 8 | Rated short-circuit breaking current | kA | 40 |
| 9 | Rated short-circuit making current (peak) | kA | 100 |
| 10 | Rated short-circuit withstand current | kA | 40 |
| 11 | Rated peak withstand current | kA | 100 |
| 12 | Rated short-circuit duration | s | 4 |
| 13 | Rated out-of-step breaking current | kA | 10 |
| 14 | Short-line fault breaking current | kA | 90% lk, 75% lk |
| 15 | Rated line charging switching current | A | 31.5 |
| 16 | Rated operating sequence | – | O-0.3s-CO-180s-CO |
| 17 | Main circuit resistance | μΩ | ≤500 |
| 18 | Rated SF6 gas pressure (20℃ gauge pressure) | MPa | 0.5 |
| 19 | Alarm/minimum function pressure (20℃ gauge pressure) | MPa | 0.45±0.03 |
| 20 | SF6 gas annual leakage rate | – | <0.5% |
| 21 | Gas moisture content (V/V) | ppm | ≤150×10⁻⁶ |
| 22 | Mechanical life | Times | 10000 |
| 23 | Radio interference level | μV | ≤500 |
| 24 | Creepage distance | mm | 3906/3150 |
| 25 | Weight of SF6 gas per unit | kg | 15 |
| 26 | Weight of each circuit breaker | kg | 2200 |
