Free Power System Short-Circuit Calculator — Looking for Engineering Feedback
I’m building a set of free engineering calculators for electrical design, and this is my second tool:
IEC 60909 Short-Circuit Current Calculator
https://ieccalc.com/002/
I made it because short-circuit calculations are often reduced to one final number, while in real projects the most important part is understanding what stands behind that number.
This calculator tries to make the calculation process more transparent and closer to real engineering practice.
It can calculate:
- 3-phase short-circuit current;
- 2-phase short-circuit current;
- 1-phase-to-earth fault current;
- peak short-circuit current;
- maximum and minimum short-circuit conditions;
- fault levels at different busbars in the network.
I also added modelling for different parts of the network, because a real short-circuit calculation is not only “source + transformer + one cable”.
The calculator allows the user to build a simple network model with different elements, for example:
- utility grid / external source;
- transformers with impedance and vector group influence;
- cable sections with length, cross-section, conductor material and resistance assumptions;
- overhead line sections;
- parallel cables or parallel paths;
- downstream busbars where fault current needs to be checked;
- different earthing arrangements for earth-fault current calculations.
For me, this was important because in real projects the fault current changes significantly from one point to another. The value at the main LV switchboard, at a distribution board, at the end of a long feeder, or after another transformer can be completely different.
So the idea is not just to calculate one “nice” short-circuit value, but to help engineers understand how the network impedance affects the result at each point.
One of the main things I wanted to include is the difference between maximum and minimum short-circuit conditions.
In many projects engineers focus mainly on the maximum fault current for equipment withstand checks, but the minimum fault current is often just as important for:
- protection operation;
- breaker tripping time;
- cable thermal withstand verification;
- fault detection sensitivity.
The calculator also includes sequence-network logic, so earth faults are not treated as a simplified version of a 3-phase fault.
Another thing I’m working on is report generation. The tool can export a DOCX report, and my goal is to make the report useful for real engineering review — not just a screenshot of results, but a structured explanation of assumptions, formulas, inputs and calculated values.
Everything runs directly in the browser, so project data is not uploaded anywhere.
This is still a work in progress, and I would genuinely appreciate feedback from engineers working with IEC 60909, protection studies, LV/MV systems or substation design.
I’m especially interested in feedback about:
- calculation logic;
- missing practical features;
- earth-fault modelling;
- report structure;
- what would make this genuinely useful in real projects.
Tool link:
https://ieccalc.com/002/