Busbar / Copper Bar Selection
Estimate required busbar cross-section from rated current, material, parallel bars, and ambient temperature; recommend standard copper/aluminum sizes and check current density.
Key points
Busbar / Copper Bar Selection: Estimate required busbar cross-section from rated current, material, parallel bars, and ambient temperature; recommend standard copper/aluminum sizes and check current density. Formula: A_req = I/(J·n·temperature factor) | J_Cu ≈ 3 A/mm², J_Al ≈ 2 A/mm². Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. Busbar ampacity depends strongly on section, number of bars, spacing, mounting, ambient temperature, altitude, and surface treatment; this tool uses current density. Parallel busbars have significant AC proximity and skin effects; do not add currents linearly—use manufacturer multi-bar tables.
Inputs
A_req = I/(J·n·temperature factor) | J_Cu ≈ 3 A/mm², J_Al ≈ 2 A/mm²Calculation model (updates with parameters)
| Required busbar cross-section | 221.1 mm² | I/(J·n·Temperature系数) |
| Recommended busbar size | 40×6 | 铜排，1 根Shunt |
| Actual cross-section | 240 mm² × 1 | 按常用Rectangle母排档bits取整 |
| Actual current density | 2.76 A/mm² | 建议铜 ≤4、铝 ≤2.5 A/mm²（自然冷却） |
| Estimated ampacity | 684 A | A·J·Temperature系数×Shunt降额 |
| Temperature derating factor | 95 % | 以 30°C 为基准 |
| Parallel derating factor | 1.00 × | 多根Shunt按 0.9 估算，实际查厂家表 |
Engineering notes
- Busbar ampacity depends strongly on section, number of bars, spacing, mounting, ambient temperature, altitude, and surface treatment; this tool uses current density.
- Parallel busbars have significant AC proximity and skin effects; do not add currents linearly—use manufacturer multi-bar tables.
- Busbars also need short-circuit dynamic (peak force) and thermal (I²t) checks; support insulator spacing must be verified for the fault current.
FAQ
- What is Busbar / Copper Bar Selection for?
- Estimate required busbar cross-section from rated current, material, parallel bars, and ambient temperature; recommend standard copper/aluminum sizes and check current density.
- What is the formula for Busbar / Copper Bar Selection?
- Core formula: A_req = I/(J·n·temperature factor) | J_Cu ≈ 3 A/mm², J_Al ≈ 2 A/mm². The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using Busbar / Copper Bar Selection?
- Busbar ampacity depends strongly on section, number of bars, spacing, mounting, ambient temperature, altitude, and surface treatment; this tool uses current density. Parallel busbars have significant AC proximity and skin effects; do not add currents linearly—use manufacturer multi-bar tables. Busbars also need short-circuit dynamic (peak force) and thermal (I²t) checks; support insulator spacing must be verified for the fault current.