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Protective Conductor Adiabatic Check

Calculate the minimum protective-conductor area, selected-conductor withstand and I²t duty from user-provided fault current, clearing time and k coefficient.

Inputs

Fault duty and conductor data

Range: 1–1,000,000 A RMS

Use the fault current and fault type applicable to the protective-conductor duty. Keep the RMS basis consistent with the selected method.

Range: 0.0001–5 s

Use total clearing time for the relevant device and fault level, not only the relay pickup or intentional delay.

Range: 1–1,000 A√s/mm²

Illustrative entry only. Verify k for conductor material, insulation, initial/final temperatures and the applicable method; do not treat the default as an Australian standard value.

Range: 0.1–1,000 mm²

Enter the actual selected conductor cross-sectional area. Mechanical minimums and installation rules are separate checks.

Result

Area margin (mm2)
11.11
Current withstand margin (A)
2,857.4
Entered fault I²t duty (A²s)
20,000,000
Calculated minimum area (mm2)
38.89
Selected conductor current withstand (A RMS)
12,857.4
Adiabatic comparison
The selected area meets this adiabatic calculation using the entered k coefficient.

Formula

Calculation logic

Formula definitions and substituted values.

Before relying on the result

  • Estimating minimum conductor area for a known fault duty
  • Checking a selected conductor against a known I-squared-t duty
  • Compare the result with the applicable installation rules and the verified conductor and protection data.

Related calculators

Compare the result with the applicable installation rules and the verified conductor and protection data.