Bus Bar Size Calculator
Determine optimal bus bar dimensions for electrical systems
Bus Bar Size Calculator
Compliant with IEC 60439 Standards (for busbar assemblies)
Results:
Calculated Current (A): 0.00
Required Area (mm²): 0.00
Current Density Used (A/mm²): 0.00
Recommended Dimensions (mm): N/A
How to Use the Calculator
Calculate by Current (Amps)
- Select "Current (Amps)" as the calculation mode.
- Enter the maximum continuous current (in Amps).
- Choose bus bar material (Copper/Aluminum) and temperature rise limit.
Calculate by Power (kW)
- Select "Power (kW)" as the calculation mode.
- Enter the power in kW, system voltage, and select system type (AC/DC, Single/Three Phase).
- For AC, input the Power Factor (PF).
- Choose bus bar material and temperature rise limit.
Understand Results
- The calculator will first determine the current (if kW is input).
- It then calculates the required cross-sectional area based on fixed current densities for Copper (1.4 A/mm²) and Aluminum (0.9 A/mm²).
- A recommended standard bus bar dimension is provided.
Bus Bar Fundamentals
What are Bus Bars?
Bus bars are metallic strips or bars, typically made of copper or aluminum, that conduct electricity within a switchgear, panel board, or busway enclosure. They are used to carry large currents and distribute power to various circuits.
Key Sizing Factors
- Current Carrying Capacity (Ampacity): The primary factor, determining the required cross-sectional area.
- Temperature Rise: Heat generated by current flow must be dissipated to prevent damage.
- Material: Copper has higher conductivity than aluminum, requiring smaller cross-sections for the same current.
- Short Circuit Withstand: Ability to handle momentary high currents during faults.
Key Formulas:
Required Area (mm²) = Current (A) / Current Density (A/mm²)
Current (A) from Power (kW):
AC Single Phase: I = (kW × 1000) / (V × PF)
AC Three Phase: I = (kW × 1000) / (√3 × V × PF)
DC: I = (kW × 1000) / V
Current density values are fixed at 1.4 A/mm² for Copper and 0.9 A/mm² for Aluminum for this calculator, based on common engineering practices for natural air cooling [^2][^3].
Calculation Formulas
Required Cross-sectional Area (A):
Area (mm²) = Current (A) / Current Density (A/mm²)
Current (I) from Power (kW):
AC Single Phase:
I = (kW × 1000) / (V × PF)
AC Three Phase:
I = (kW × 1000) / (√3 × V × PF)
DC Systems:
I = (kW × 1000) / V
Example Calculation
Calculate bus bar size for a 50kW, 400V, 3-Phase AC system (PF=0.8), Copper material:
Power (kW): 50 kW
Voltage (V): 400 V
System: AC Three Phase
Power Factor (PF): 0.8
Material: Copper
1. Calculate Current (I):
I = (50 × 1000) / (√3 × 400 × 0.8) ≈ 50000 / (1.732 × 400 × 0.8) ≈ 50000 / 554.24 ≈ 90.21 A
2. Calculate Required Area (Copper, Current Density = 1.4 A/mm²):
Area = 90.21 A / 1.4 A/mm² ≈ 64.44 mm²
A common copper bus bar size that meets this is 25mm x 3mm (75 mm²).