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 device for 126kV-class power systems, suitable for AC 50Hz power transmission and distribution networks. Its core features include using SF6 gas as both insulating and arc-extinguishing medium, adopting the self-energy arc-extinguishing principle, and matching with a spring operating mechanism, achieving strong breaking capacity, low operating energy, and high reliability.

I. Main Structure and Working Principle

This circuit breaker is an outdoor three-phase AC device. Each unit consists of three single-pole components mounted on the same crossbeam and one spring operating mechanism, with mechanical interlocking between the three poles. The upper part of each single pole is the arc extinguishing chamber, the middle part is the post insulator 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 build the air pressure required for arc extinguishing. This allows the use of a smaller-diameter pressure cylinder, significantly reducing the burden on the operating mechanism. During opening, the mechanism drives the moving contact system to move; the separation of moving and static contacts generates an arc, whose energy increases the pressure inside the pressure cylinder. Subsequently, high-pressure SF6 gas is ejected bidirectionally from the nozzle, rapidly extinguishing the arc. During closing, the moving parts move in reverse to return to the closed state, while SF6 gas is replenished into the pressure cylinder through the gas return device, preparing for the next opening operation.

The sealing system uses O-rings for static sealing. For dynamic sealing in the crank arm box, rotary seals paired with X-shaped sealing rings are used to reduce wear and leakage.

II. Rated Technical Parameters

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

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

SF6 gas parameters: At 20°C, the rated working pressure is 0.50MPa ± 0.015MPa. The gas replenishment alarm pressure is 0.45MPa ± 0.015MPa, and the circuit breaker locking pressure is 0.40MPa ± 0.015MPa. The annual leakage rate of SF6 gas 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 stroke of the moving contact is 148mm ± 4mm, and the contact stroke 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 lifespan can reach 6000 operations. The rated operation sequence is "opening - 0.3s - closing-opening - 180s - closing-opening".

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

III. Operating Environmental Conditions

Normal operating environments must comply with national standards, mainly including: ambient temperature range from -40°C to +40°C; altitude no more than 3000m; wind speed no more than 34m/s; seismic acceleration no more than 0.2g in the horizontal direction and no more than 0.1g in the vertical direction; air pollution level no more than Class Ⅳ in GB5582; installation location is outdoor. Some models may specify an altitude no more than 2000m and an ambient temperature range from -30°C to +40°C.

IV. Installation, Operation and Maintenance

Operators must carefully read the product manual before installation, use and maintenance. After installation, on-site tests are required, including mechanical characteristic adjustment, circuit resistance measurement, SF6 gas micro-moisture content detection, and sealing performance inspection. During daily use, close attention must be paid to the SF6 gas pressure status; timely gas replenishment is required when the pressure drops to the gas replenishment alarm value, and the circuit breaker must be prohibited from operation when the pressure drops to the locking pressure. Regular maintenance shall be carried out in accordance with the technical documents provided by the manufacturer.

V. Safety Specifications and Precautions

This circuit breaker is a high-voltage dangerous device, and all operations must strictly comply with safety regulations. When handling SF6 gas, relevant environmental and safety guidelines must be followed. If there are any questions about the equipment or more detailed information is needed, please contact the manufacturer directly.