Indal Handbook For Aluminium Busbar Hot -

Because aluminium expands and contracts, flat washers are useless in hot environments.

The INDAL Handbook does not forbid aluminium busbars from running hot, but it imposes strict conditions: indal handbook for aluminium busbar hot

Final engineering rule from INDAL: A hot aluminium busbar is not a failed busbar—provided the heat is uniform, the joint pressure is maintained, and the thermal expansion is managed. A single hot joint is a pending arc flash. Because aluminium expands and contracts, flat washers are

If you need the actual numerical tables from the original INDAL handbook (current ratings vs. cross-section vs. temperature), let me know and I can reconstruct those based on E91E alloy datasheets. Final engineering rule from INDAL: A hot aluminium

While often considered a "high frequency" issue, the INDAL handbook notes that at high currents (4000A+), the skin effect becomes a thermal problem. As the bar heats, the resistivity rises, pushing current toward the surface.

Solution prescribed: Instead of a single massive thick bar (e.g., 120x10mm), use multiple thinner bars (e.g., 120x5mm x 2) separated by a gap equal to their thickness. This reduces AC resistance and lowers the operating temperature by 15-20°C.