Some manufacturer websites (Prysmian, Nexans, Southwire) offer free non-adiabatic calculation tools. However, verify they follow IEC 60949 explicitly.
The standard models the thermal behavior of a cable during a short circuit based on energy balance. During a fault, the temperature of the conductor rises rapidly. The rate of this rise depends on:
Over-sizing cables because of conservative adiabatic calculations is expensive. For example, a 240 mm² cable might pass adiabatic tests, but a 185 mm² cable could handle the same fault under non-adiabatic rules. The difference can save thousands of dollars per kilometer. iec 949 pdf work
From the cable manufacturer’s datasheet (often a PDF), extract:
The phrase "IEC 949 PDF work" represents a critical engineering task: ensuring cables survive short circuits using non-adiabatic methods. By obtaining the correct PDF (IEC 60949), understanding the formulas, and using the right tools (spreadsheets or software), you can size cables more efficiently, save project costs, and maintain compliance. During a fault, the temperature of the conductor
The calculation is rooted in the conservation of energy. The electrical energy input during the fault time must equal the thermal energy absorbed by the conductor material. This relationship can be expressed as:
$$ \int_0^t_f I^2(t) , dt = K^2 S^2 $$
Where:
For very short fault durations (typically less than 5 seconds), the standard often employs an adiabatic approximation. This assumes that all heat generated in the conductor remains within the conductor during the fault because there is insufficient time for heat to transfer to the insulation or surroundings. The difference can save thousands of dollars per kilometer