As explained by Electrical Installation Wiki in their article “Sizing of Busbar Trunking Systems (Busways)”, selecting the right busbar trunking system is a simplified process compared to traditional cable distribution. Unlike cables, busways do not require adjustments for insulation materials, installation methods, or grouping correction factors, making their selection more straightforward.
Key Considerations for Busbar Sizing
- Rated Current Capacity – The busbar cross-section is predetermined by the manufacturer based on rated current, assuming 35°C ambient air temperature and three loaded conductors. The absorbed current (In) must be calculated considering the layout and the connected loads.
- Ambient Temperature Adjustments – If the operating temperature exceeds 35°C, a correction factor must be applied. Manufacturers provide these factors to ensure accurate sizing. For example, Schneider Electric’s high-power busbars (up to 4000 A) require specific correction values.
- Neutral Current Considerations – When 3rd harmonic currents are present, the neutral conductor may carry significant current, leading to increased power losses. Proper busway selection should account for this factor to maintain efficiency and prevent overheating.
- Trunking System Layout – The positioning of current consumers, power source location, and available mounting options determine the layout. Common configurations include:
- Single distribution lines covering a 4 to 6-meter area
- Tap-off units with integrated protection devices for power distribution
- A single feeder supplying multiple loads with varying power requirements
Efficient Busbar Trunking System Planning
Once the layout is finalized, the total absorbed current (In) is calculated as the sum of all load currents (IB), adjusted by a clustering coefficient (kS):
In=∑(IB×kS)In = \sum (IB \times kS)In=∑(IB×kS)
This accounts for the fact that not all connected loads operate simultaneously or at full capacity, allowing for an optimized busbar design that balances efficiency and cost-effectiveness.
Future-Proofing Electrical Systems with Busbar Solutions
Properly sizing a busbar trunking system ensures efficient power distribution, reduced energy losses, and long-term reliability. With advantages like scalability, simplified installation, and enhanced safety, busbars are quickly replacing traditional cabling in modern industrial and commercial power systems.
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Article with all rights reserved, courtesy of Electrical Installation Wiki.
