XGN2-12 Box-Type Fixed AC Metal-Enclosed Switchgear

I. Structural Features

1. Metal-enclosed box-type structure: The cabinet frame is fabricated from welded angle steel or assembled from C-section and G-section profiles. The interior comprises four independent compartments—the circuit breaker chamber, busbar chamber, cable chamber, and relay chamber—separated by steel plates or metal enclosures.

2. Dual-side maintenance design: The switchgear permits maintenance from both sides. The front facilitates servicing of secondary relay components, operating mechanisms, mechanical interlocks, transmission components, and circuit breakers. The rear allows maintenance of main busbars and cable terminations. Lighting is provided within both the circuit breaker compartment and cable compartment.

3. Inspection windows and illumination: Operational status of key internal components can be monitored through inspection windows and lighting fitted to the door panels.

4. Earthing Design: A grounding copper busbar runs parallel to the cabinet width beneath the front door, ensuring secure and reliable equipment earthing.

II. Electrical Performance

1. Insulation Performance: Phase-to-phase and phase-to-ground air insulation distances exceed 125mm. Support insulators (or bushings) with increased creepage distances are employed throughout the cabinet, providing high insulation strength and stability.

2. Complies with domestic and international standards including GB3906 ‘3-35kV AC Metal-Enclosed Switchgear’ and IEC60298 ‘AC Metal-Enclosed Switchgear and Control Gear’, meeting Class I design requirements for severe conditions.

3. Five-prevention interlocking functions: Comprehensive anti-misoperation features include:
   - Preventing load-breaking/closing of isolating switches
   - Preventing erroneous tripping/closing of circuit breakers
   - Preventing entry into live compartments
   - Preventing closing of earthing switches under load
   - Preventing closing of earthing switches with live conductors
4. Mandatory mechanical interlocking mechanisms are employed between main switches, isolating switches, earthing switches, and cabinet doors to ensure safe and reliable operation.

5. Circuit Breakers and Isolating Switches: The main switch employs ZN28A-12 series vacuum circuit breakers, while isolating switches utilise GN30-12 rotary or GN22 series high-current isolating switches, supporting frequent operation.

6. Rotary isolating switches ground the conductor in the open position, creating a ‘metallic separation’ to ensure maintenance personnel safety.

7. Cable Entry/Exit Methods: Supports both overhead cable entry/exit via cabinet top and cable entry/exit via cabinet base.

8. Operating Mechanisms: Includes electromagnetic and spring-storage types to meet diverse user requirements.

III. Normal Operating Conditions
1. Ambient Air Temperature: -15°C to +40°C.
2. Altitude: 1000 metres and below.
3. Humidity conditions: Daily average relative humidity ≤95%, daily average water vapour pressure ≤2.2kPa; monthly average relative humidity ≤90%, monthly average water vapour pressure ≤1.8kPa.
4. Seismic intensity: ≤8 on the Mercalli scale.
5. Suitable for locations free from significant contamination by corrosive or flammable gases.
Note: Special requirements may be addressed through consultation with the company.