Overview
The LW3-12 series outdoor high-voltage sulfur hexafluoride (SF6) circuit breakers are engineered for reliable operation in 12kV power distribution systems. Designed specifically for outdoor use, they utilize SF6 gas as both the arc-extinguishing and insulating medium, ensuring high performance with minimal maintenance requirements.
Featuring a compact modular design, the LW3 series delivers superior arc-quenching capability, excellent dielectric strength, and low operational effort. Its robust construction ensures an extended service life, reduced fire hazard, and a smaller installation footprint compared to conventional 10kV outdoor breakers, significantly enhancing system safety and reliability in demanding environments.
Model Designation
- L: Uses SF6 gas as the arc-extinguishing and insulating medium.
- W: Outdoor type, suitable for outdoor installations.
- 3: Series design number.
- 12: Rated voltage (kV).
- I / II / III: Operating mechanism types: I : Manual spring, II : Motorized spring (AC), III : Magnetic (DC).
- 400/630: Rated current (A).
- 6.3 / 8 / 12.5 / 16: Rated short-circuit breaking current (kA).
Construction
The breaker’s pole unit contains sealed SF6 gas chambers housing fixed and moving contacts. Terminal markings follow standard conventions: primary terminals labeled P1 and P2, secondary current transformer terminals marked S1 and S2 (where applicable). All units are factory-filled, hermetically sealed, and rigorously tested per IEC 60265-1 (1988) and GB 3804-1990 standards.
The enclosure is constructed from 304L stainless steel for exceptional corrosion resistance in harsh outdoor conditions. Safety Warning: Do not attempt to open or modify the SF6 gas compartment: gas handling must only be performed by certified personnel using approved recovery equipment.
Technical Parameters
Service Conditions
- Ambient temperature range: -30 degC to +40 degC
- Altitude: <=1,000 m above sea level
- Installation environment: Outdoor, standard atmospheric conditions per IEC 60265-1 and GB 3804-1990
Technical Data
| Parameter | Value |
|---|---|
| Rated voltage | 12 kV |
| Rated frequency | 50 Hz |
| Rated current | 400 A / 630 A |
| Rated short-circuit breaking current |
6.3 kA / 8 kA / 12.5 kA / 16 kA |
| Rated short-circuit making current (peak) |
16 kA / 20 kA / 31.5 kA / 40 kA |
| Rated short-time withstand current (3s) |
6.3 kA / 8 kA / 12.5 kA / 16 kA |
| Power frequency withstand voltage (1 min) |
42 kV (between phases and earth) 48 kV (across open contacts) |
| Lightning impulse withstand voltage |
75 kV (between phases and earth) 85 kV (across open contacts) |
| Mechanical endurance | : >=3,000 operations |
| SF6 gas pressure (at 20 degC, gauge) |
0.04 MPa |
Installation & Wiring
Installation Diagram
The LW3-12 SF6 circuit breaker features a standardized mounting footprint for easy integration into existing 12kV outdoor switchgear structures. Ensure adequate clearance for safe operation and maintenance access.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Total height | 1,850 |
| Width (per pole) | 320 |
| Depth | 580 |
| Pole center distance | 340 |
| Mounting hole pattern | 200 x 200 |
| Primary terminal height | 1,650 |
Selection & FAQs
Selection Guide
- Confirm a 12kV, 50Hz outdoor system and select 400A or 630A after continuous-load, ambient and conductor temperature-rise checks.
- Choose 6.3kA, 8kA, 12.5kA or 16kA breaking capacity above the prospective fault current and verify matching making and three-second withstand ratings.
- Select type I manual spring, type II AC motorized spring or type III DC magnetic operation to match local/remote control and auxiliary power.
- Confirm 0.04MPa SF₆ gauge pressure at 20°C, required monitoring provisions, sealed-for-life expectations and compliant gas-recovery support.
- Verify altitude derating above 1000m, mounting footprint, 340mm pole spacing, insulation clearances, terminal forces, foundation and grounding.
Frequently Asked Questions
Q1: What is the maximum short-circuit breaking current?
The rated short-circuit breaking current is up to 16 kA. Peak making current reaches 40 kA. Confirm your specific grid fault level with our engineering team.
Q2: Can this SF6 breaker be installed at 1,500 meters altitude?
Standard models are rated for altitudes up to 1,000 m. For installations above 1,000 m, derating applies. Contact us for altitude-specific technical adjustments.
Q3: How is the SF6 gas pressure specified for this model?
The nominal gauge pressure is 0.04 MPa at 20°C. This ensures optimal arc extinguishing and dielectric strength. Verify gas monitoring requirements with our technical team.
Q4: Which international standards does this circuit breaker comply with?
It complies with IEC 60265-1 and GB 3804-1990 standards. Performance values meet these requirements for 12kV outdoor applications. Factory test reports are provided upon request.
Q5: Are routine factory tests performed before shipment?
Yes, standard routine tests include power frequency withstand voltage and mechanical operation checks. Special type tests are subject to confirmation. Specify your project testing requirements during order placement.
Q6: Where is this 12kV outdoor circuit breaker typically applied?
It is designed for outdoor 12kV distribution networks and industrial power systems. It handles 400A to 630A rated currents in standard atmospheric conditions. Confirm environmental suitability for your site.
Q7: Is the mechanical endurance customizable for frequent switching?
The standard mechanical endurance is at least 3,000 operations. Custom configurations for higher operation frequencies are subject to confirmation. Discuss your specific switching duty cycle with our sales team.