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LW34-40.5 Sulfur Hexafluoride (SF₆) Circuit Breaker
1. Basic Product Positioning
The LW34-40.5 outdoor sulfur hexafluoride (SF₆) circuit breaker is a three-phase AC 50Hz outdoor high-voltage electrical equipment. It is mainly suitable for the control and protection of 40.5kV power transmission and distribution systems, can be used as an interconnection circuit breaker, and is also compatible with working scenarios involving switching capacitor banks.
2. Core Product Features
Excellent Breaking Performance: Adopts a pressure-blast arc-extinguishing chamber with short arcing time, and the rated short-circuit breaking current can reach 40kA. It has a long electrical life—under-rated voltage, it can continuously break 31.5kA/40kA short-circuit current up to 21 times without maintenance or replacement of SF₆ gas.
High Operational Reliability: Equipped with a CT14-type spring operating mechanism, it features outstanding mechanical reliability with a mechanical life of over 3,000 operations (some specifications show a maximum of up to 10,000 operations). It has strong arc-extinguishing capability, can adapt to frequent operation conditions, and maintains stable insulation performance—no restriking occurs when switching 630A capacitor bank current.
Optimized Structural Design:
Flexible Current Transformer Configuration: Each unit can be equipped with up to 12 current transformers for users to choose from. Among them, LW34-40.5 and LW34C-40.5 can be equipped with 3–12 built-in current transformers, while LW34A-40.5 is compatible with external current transformers. The overall structure is simple and compact, with a long maintenance-free period and a low maintenance rate.
High-Quality Chassis Craftsmanship: Formed by cold-bending steel plates into a "U" shape and then welding, it has high mechanical strength and rigidity. It adopts an overall surface treatment process, featuring strong waterproof and dustproof capabilities, an attractive appearance, and excellent corrosion resistance.
Flexible Arrangement Modes: Offers two arrangement forms—indoor and outdoor. Each arrangement form can be divided into a circuit breaker compartment and a measurement & maintenance compartment. Each compartment consists of a fixed part and a movable part: the fixed part includes isolation plugs, earthing switches, and local operation control cabinets; the movable part uses a trolley as the base, integrating different electrical components into an electrically modular unit that can be moved as a whole. The movable part of the circuit breaker compartment is composed of a self-energized SF₆ circuit breaker, current transformers, and isolation plugs; the movable part of the measurement & maintenance compartment is composed of voltage transformers, surge arresters, and isolation plugs.
Convenient Operation & Maintenance: Equipped with a new MKZ-type SF₆ pointer density gauge. The pressure gauge reading is not affected by temperature changes, facilitating real-time monitoring of gas status and easy operation.
3. Compliance Standards
The product complies with the requirements of the national standard GB1984-89 AC High-Voltage Circuit Breakers and the International Electrotechnical Commission (IEC) standard IEC56 High-Voltage AC Circuit Breakers, and is compatible with general specifications in the power industry.
4. Main Technical Parameters Table
5. Summary of Core Advantages
Excellent breaking performance and high arc-extinguishing efficiency;
Long electrical life, reducing maintenance frequency;
Reliable insulation performance, adapting to complex working conditions;
Long mechanical life, suitable for frequent operations;
Safe and reliable operation with low maintenance workload;
Flexible structure, adapting to different installation and usage needs.
6. Frequently Asked Questions (FAQ)
Q1: Can the LW34-40.5 circuit breaker be installed in high-altitude areas?
A1: The standard model of the LW34-40.5 circuit breaker is designed for general altitudes, but customized versions can be provided to adapt to high-altitude environments (e.g., up to 4,000m) based on specific project requirements. It is recommended to confirm the altitude parameter with the supplier before purchase to ensure compatibility.
Q2: How often does the SF₆ gas in the circuit breaker need to be checked or refilled?
A2: The LW34-40.5 circuit breaker has a low annual gas leakage rate (≤0.3% typically) and can maintain stable gas pressure for a long time. Under normal operation, it is recommended to check the SF₆ gas pressure using the built-in MKZ-type density gauge every 6–12 months. Refilling is only required if the pressure drops below the rated value (0.45MPa at 20℃), which is rare under standard usage conditions.
Q3: Is the current transformer configuration of the LW34-40.5 customizable?
A3: Yes, it is highly customizable. Each unit can be equipped with 3–12 current transformers (built-in for LW34-40.5/LW34C-40.5, external for LW34A-40.5). The accuracy class (e.g., Class 0.2S, Class 0.5) and ratio of the current transformers can also be adjusted according to the user’s measurement and protection needs.
Q4: What should be done if the SF₆ density gauge shows abnormal pressure?
A4: First, confirm whether the pressure reading is indeed abnormal (note: the MKZ-type gauge is temperature-insensitive, so no temperature correction is needed). If the pressure is lower than the rated 0.45MPa, immediately stop using the circuit breaker, isolate it from the power system, and contact professional maintenance personnel to check for gas leaks. Do not attempt to refill SF₆ gas or disassemble the gauge without professional guidance.
Q5: Can the LW34-40.5 circuit breaker be used in harsh weather conditions (e.g., extreme cold, heavy pollution)?
A5: The standard model can withstand ambient temperatures from -30℃ to +40℃ and is suitable for air pollution levels up to Grade Ⅳ (per GB/T 5582). For extreme cold conditions (e.g., -40℃), a low-temperature customized version with modified seals and lubricants is available. For areas with severe pollution, additional anti-pollution coatings on the porcelain insulators can be provided to enhance performance.
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