Copper Busbar For Medium-voltage Switch Cabinets
The Technical Specific for the copper busbar
Parameter category |
Standard type |
High-performance type |
Remark |
Material |
T2 Purple Copper (Cu ≥ 99.9%) |
T1 Anodic copper (Cu ≥ 99.95%) |
T1 has a higher conductivity and is suitable for high-frequency applications. |
Cross-sectional shape |
Rectangle/ Rounded Rectangle |
U-shaped/Tube-shaped/Special-shaped |
40.5kV preferred tubular busbar, with superior insulation performance |
Current density |
1.5 - 2.0 A/mm² (below 1250 A) |
2.0 - 2.5 A/mm² (Silver plating treatment) |
The greater the current, the lower the recommended density. |
Short-term withstand current |
31.5kA/1s~63kA/4s |
80kA/0.5s |
Select based on the system short-circuit capacity |
standards |
GB/T 5585.1-2005 GB/T 7251.1-2023 |
IEC 61439-2 |
Meet the international standards for medium-voltage cabinets |
The application for the copper busbar
1.Medium-voltage switchgear main busbar system
10-12kV metal-encased cabinets: Main busbar (80×8mm~125×10mm) connects each functional unit.
40.5kV air-insulated cabinets: Preferentially use tubular copper bars to enhance insulation performance and reduce local discharge.
Wind power / photovoltaic grid-connected cabinets: Double-layer copper bars (5mm thick ×2) can carry a current of up to 7000A, and require a ventilation design in conjunction.
2.Branching and Connecting System
Connection between circuit breakers and disconnectors: 60×6mm to 80×8mm copper strips, with short-term withstand capacity of ≥50kA
Connection strips for PT/CT: 30×4mm to 50×5mm, with high precision requirements to ensure measurement accuracy
Connection for cabinets: Special connecting copper strips are used, with reserved thermal expansion gap (3-5mm)
3.Special Applications
Generator outlet switch cabinet: U-shaped copper busbar, capable of withstanding high current (≥5000A) and electrodynamic force
Rail transit traction inverter: High-purity copper busbar, low-impedance design, reducing voltage drop
FAQ for the copper busbar
Q: Why are copper busbars used instead of aluminum busbars in medium voltage cabinets?
A: The conductivity of copper busbars is 1.6 times that of aluminum busbars. This results in lower resistance (40% less energy consumption), 2-3 times higher mechanical strength, and better corrosion resistance, making them suitable for the long-term stable operation of medium voltage cabinets.
Q: Why is it recommended to use tubular busbars in 40.5kV switch cabinets?
A: Tubular busbars have a hollow structure, large heat dissipation area, and small skin effect. They have a greater flow rate at the same cross-sectional area, a more uniform electric field distribution, better insulation performance, and are particularly suitable for high-voltage levels.
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