Recommended Outdoor Tubular Busbars

Aluminium tubular busbars are generally recommended for outdoor high-voltage applications due to their high strength-to-weight ratio, corrosion resistance, and efficient current-carrying capacity.

Material and Alloy Selection

For outdoor installations, aluminium alloys are preferred over copper for new high-voltage busbars because they offer lighter weight, high stiffness, and good corrosion resistance, which reduces structural load on support insulators and gantry steelwork . Commonly used alloys include 6101B T6 for higher mechanical strength and 6101B T7 for higher electrical conductivity, depending on whether mechanical or electrical performance is prioritized . Copper may still be used for extensions to existing copper busbar systems .

Design Considerations

Key parameters for selecting tubular busbars include:

• Outer diameter and wall thickness: Determines mechanical strength and thermal performance.
• Current rating: Typical continuous current ratings for aluminium busbars are 1250A or 2000A, with higher ratings available for cast resin or bespoke systems .
• Environmental conditions: Outdoor exposure to wind, ice, UV, and corrosive atmospheres should be considered. Aluminium naturally forms a protective oxide layer, and anodizing or surface treatments can extend service life beyond 30 years .
• Span between supports: Tubular busbars provide high section modulus and moment of inertia, allowing spans of 8–15 meters without excessive sag or vibration .

Fittings and Connections

• Open terminal systems should use fittings compliant with ENA TS 41-11 for aluminium or ENA TS 41-16 for copper .
• Current-carrying clamps: Fixed fittings require at least two complete clamps for mechanical stability, while sliding fittings use clamps based on current rating .
• Copper-to-aluminium connections require precautions to prevent electrochemical corrosion .

Alternative Systems

• Cast resin busbars (e.g., Vertiv™ PowerBar) are suitable for outdoor applications up to 1000V, with IP68 protection, chemical resistance, and ratings up to 6300A. They are maintenance-free and can be customized to fit complex layouts .

Practical Recommendations

1. Use aluminium tubular busbars for new outdoor high-voltage substations due to their mechanical and thermal advantages.
2. Select alloy grade based on the balance between mechanical strength and electrical conductivity.
3. Ensure fittings and clamps comply with relevant ENA standards to maintain safety and reliability.
4. Consider environmental protection such as anodizing or resin encapsulation for harsh outdoor conditions.
5. Verify current rating and span to prevent thermal overload and mechanical failure. By following these guidelines, outdoor tubular busbars can achieve long service life, high reliability, and efficient power distribution in substations and transmission structures .