LW36-126kV/1600A Outdoor High-voltage Sulfur Hexafluoride Circuit Breaker

The LW36-126 outdoor self-energy high-voltage sulfur hexafluoride circuit breaker is a key control and protection equipment used in 126kV voltage grade power systems, suitable for AC 50Hz power transmission and distribution networks. Its core feature is the use of SF6 gas as the insulation and arc extinguishing medium, and the application of the self-energy arc extinguishing principle, combined with a spring operating mechanism, to achieve strong breaking capacity, low operating power and high reliability.

I. Main Structure and Working Principle

This circuit breaker is an outdoor three-phase AC equipment, each unit consists of three single poles mounted on the same crossbeam and a spring operating mechanism, with mechanical linkage between the three poles. The upper part of the single pole is the arc extinguishing chamber, the middle part is the post porcelain bushing, and the lower part is the crank arm box.

The arc extinguishing chamber adopts the self-energy principle, which uses the arc's own energy to establish the air pressure required for arc extinguishing, so a smaller diameter pressure cylinder can be used, significantly reducing the load on the operating mechanism. During opening, the mechanism drives the moving contact system to move, the moving and static contacts separate to generate an arc, the arc energy increases the pressure in the pressure cylinder, and then the high-pressure SF6 gas is ejected bidirectionally from the nozzle to quickly extinguish the arc. During closing, the moving parts move reversely to return to the closed state, and at the same time, SF6 gas is supplemented into the pressure cylinder through the air return device to prepare for the next opening.

The sealing system uses O-rings for static sealing, and the dynamic sealing in the crank arm box adopts rotary sealing combined with X-type sealing rings to reduce wear and leakage.

II. Rated Technical Parameters

Basic electrical parameters: The rated voltage is 126kV, and the rated frequency is 50Hz. The rated current is commonly 3150A. The rated short-circuit breaking current is 40kA, and the rated peak withstand current and rated short-circuit closing current are both 100kA (peak value).

Insulation level: Under the condition of an altitude of 2000m, the 1min power frequency withstand voltage (dry test/wet test) between poles or between pole and ground is 230kV/260kV (effective value), and the lightning impulse withstand voltage (peak value) is 550kV/622kV. When the SF6 gas pressure is zero, it can still withstand a 5min power frequency withstand voltage of 95kV.

SF6 gas parameters: At 20℃, the rated working pressure is 0.50MPa±0.015MPa. The air supply alarm pressure is 0.45MPa±0.015MPa, and the circuit breaker locking pressure is 0.40MPa±0.015MPa. The annual SF6 gas leakage rate is required to be no more than 1%, and the gas moisture content is no more than 150ppm (volume ratio).

Mechanical and operating characteristics: The total travel of the moving contact is 148mm±4mm, and the contact travel is 25mm±3mm. The typical opening time is 28ms±5ms, and the closing time is no more than 110ms. The opening speed and closing speed are 4.8m/s±0.5m/s and 2.8m/s±0.5m/s respectively. The mechanical life can reach 6000 times. The rated operating sequence is "Open - 0.3s - Close-open - 180s - Close-open".

Other parameters: The main circuit resistance is no more than 45μΩ. The total weight of the circuit breaker (including the mechanism) is about 1400kg, and the total weight of SF6 gas is about 6kg. The control circuit power is usually DC220V or DC110V.

III. Operating Environment Conditions

The normal operating environment must comply with national standards, mainly including: the ambient temperature range is -40℃ to +40℃; the altitude does not exceed 3000m; the wind speed is no more than 34m/s; the seismic acceleration is no more than 0.2g in the horizontal direction and no more than 0.1g in the vertical direction; the air pollution level does not exceed Grade IV in GB5582; the installation site is outdoors. Some models may specify that the altitude does not exceed 2000m and the ambient temperature is -30℃ to +40℃.

IV. Installation, Operation and Maintenance

Operators must carefully read the product manual before installation, use and maintenance. On-site tests shall be carried out after installation, including mechanical characteristic adjustment, loop resistance measurement, SF6 gas micro-moisture content detection and sealing performance inspection, etc. In daily use, close attention shall be paid to the SF6 gas pressure status. When the pressure drops to the air supply alarm value, it shall be supplemented in time, and when it drops to the locking pressure, the circuit breaker will be prohibited from operating. Regular maintenance shall be carried out in accordance with the technical documents provided by the manufacturer.

V. Safety Specifications and Notes

This circuit breaker belongs to high-voltage dangerous equipment, and any operation must strictly comply with safety regulations. When handling SF6 gas, corresponding environmental protection and safety guidelines must be followed. If you have any questions about the equipment or need more detailed information, please directly contact the manufacturer.