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Current carrying capacity of busbar

Description

Calculate the maximum continuous current-carrying capacity of busbars based on material, size, environment, and installation conditions.

Supports:

  • Copper / Aluminum materials
  • Rectangular / Round busbars
  • Ambient temperature and temperature rise
  • Ventilation (open air, enclosed, forced)
  • Installation position (horizontal, vertical, stacked)
  • Surface finish (unpainted, dark painted)
  • Parallel busbars

Key Formula

I = K × √(A × ΔT) × f₁ × f₂ × f₃

Where:
K: Material factor (Cu≈1.0, Al≈0.6)
A: Cross-sectional area (mm²)
ΔT: Allowable temperature rise (°C)
f₁: Ventilation factor
f₂: Position factor
f₃: Surface factor

Example

Copper rectangular busbar, 100×10mm, ambient 35°C, ΔT=30°C, open air, horizontal, unpainted
→ Current capacity ≈ 2800 A

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