China Busbar Suppliers - Customized Copper Busbars for Medium-Voltage Switch Cabinets, Factory Direct Solutions
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
01
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.
02
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).
03
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.
Q
What surface treatments are available for copper busbars and what are their benefits?
A
Common surface treatments include silver plating, tin plating, and nickel plating. Silver plating improves conductivity and reduces contact resistance, making it ideal for high-current applications. Tin plating offers better corrosion resistance and solderability. Nickel plating provides superior hardness and oxidation resistance for demanding environments.
Q
How should copper busbars be sized for a specific application?
A
Sizing is based on the rated current, short-circuit withstand capacity, ambient temperature, and installation conditions. The current density is typically 1.5–2.5 A/mm² depending on the application. Thermal expansion gaps (3–5mm) must also be considered during installation to prevent mechanical stress.
Q
What standards do copper busbars need to comply with for medium-voltage cabinets?
A
For domestic use, copper busbars should comply with GB/T 5585.1-2005 (material standard) and GB/T 7251.1-2023 (switchgear assembly standard). For international projects, IEC 61439-2 is the applicable standard, ensuring compatibility with global medium-voltage cabinet requirements.
Q
How do you prevent overheating of copper busbars during long-term operation?
A
Overheating can be prevented by selecting the correct cross-sectional area based on current load, ensuring proper ventilation design within the cabinet, applying high-quality surface treatment to reduce contact resistance, and conducting regular inspections of connection joints to detect any signs of oxidation or loose connections.
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