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Distribution Fault Study Builder

Radial Network · Multi-Bus Fault Level Schedule

Build a simple radial distribution network — utility source, transformers, cables and buses — and calculate three-phase prospective fault current at each bus in the network. Add elements in sequence from source to load; each bus element captures the fault level at that point, producing a fault-level schedule useful for switchgear rating verification and protection coordination.

CALCULATOR

Fault Study Builder

NETWORK (SOURCE → LOAD)
⚡ UTILITY SOURCE
Transformer
Bus (Fault Point)
FAULT LEVEL SCHEDULE
Main Switchboard (0.415kV)
FAULT CURRENT
13.38 kA
FAULT LEVEL
9.62 MVA

Results for guidance only. Verify against current standards and manufacturer data.
Not a substitute for engineering judgement or a licensed professional.

Methodology

Elements are added in series from utility source to load, matching the physical network topology. Each transformer and cable contributes its impedance (converted to per-unit on the common MVA base) to a running cumulative total. Each Bus element captures the fault level at that specific point by calculating fault current from the cumulative impedance up to that point — producing a full schedule showing how fault level reduces moving from source to load.

Assumptions & Limitations

  • Radial network only — does not support parallel paths, ring configurations, or multiple sources
  • Motor contribution to fault current is not currently included
  • Magnitude-only impedance calculation — X/R ratio and asymmetrical peak current are not derived
  • This tool builds a foundation for future functionality: saved projects, N-1 scenarios, and protection coordination

Related Calculators

AusElectrical.tools
Built with reference to AS/NZS 3000, AS/NZS 3008, AS/NZS 1359
Results for guidance only — not a substitute for engineering judgement
Does not reproduce copyrighted Standards Australia material. Always consult current standards for compliance.