SHORT-CIRCUIT CHAIN ANALYSIS

FaultChain: Short-Circuit Protection & I²t Calculator

Calculate prospective short-circuit current along a radial circuit and check protective-device breaking capacity. Use the free single-path calculator below, or open Pro for a graphical distribution model, cable thermal checks and protection charts.

FREE CALCULATOR

Single upstream path

General source fault level, one protective device and one cable. Use it for a quick check.

Inputs

3φ radial

Line voltage

Prospective Icc at source

Source X/R Protective device Rated current

Breaking capacity

Cable material Cross-section One-way length

Conductor temperature

°C

Cable reactance

Ω/km

Use project/manufacturer data when known. The default is a screening assumption.

Prospective current is calculated from source and cable impedance.

How to use the short-circuit protection calculator

Start with the prospective fault current at the source, system voltage and source X/R ratio. Enter the cable material, cross-section, one-way length, temperature and reactance. The free calculator estimates the three-phase fault current at the cable end and checks the entered protective-device breaking capacity.

Need a transformer-terminal starting estimate? Use the transformer short-circuit calculator. Read fault current, breaking capacity and equipment SCCR explained before interpreting the result.

Peak let-through current and I²t in Pro

The Pro workspace separates prospective RMS fault current, natural peak current and an entered current-limiting cut-off point. It also provides cable thermal-energy check. Built-in generic presets are not verified manufacturer curves: use applicable manufacturer data and record the source for each device.

For the meaning of the energy comparison and the data it requires, read the I²t and fuse let-through energy guide. For conductor selection with ampacity, derating and voltage-drop checks, use the IEC cable sizing calculator.

For curve interpretation and the boundary between TCC review, selectivity, cascading and SCCR, use the Protection Coordination and TCC guide.

What does the result establish?

It helps identify numerical conflicts in the entered model. It does not establish verified selectivity, cascading or a certified equipment SCCR. Generic time-current bands and user-entered points require review against the applicable manufacturer combination data and project requirements.

Review the FaultChain calculation method, catalogue coverage and data provenance, and Free and Pro options.

Navigate: mouse wheel zooms at the cursor · drag empty canvas or middle-drag to pan · Fit restores the overview. Right-click a component for actions; select a node or cable for the fault location.

No calculation

FAULT LOCATION—

PROSPECTIVE I''k—

NATURAL PEAK ip—

EQUIVALENT Z—

Calculate to evaluate thermal energy and current limitation.

No calculation yet.

Node	Voltage	R	X	I''k	Natural ip	Cut-off ip

Use Calculate all to evaluate every fault node and component assessment.

Node	I''k	Natural ip	Cut-off ip	Nearest protection	Cable thermal	Status

Calculate a fault to populate device checks.

Protection TCC / thermal checkLog-log view · generic bands and user-referenced points are reference data

No fault result

Calculate a fault or select a protection device to inspect its curve data.

TCC and coordination results are calculation aids only. Generic curves are not manufacturer curves. Selectivity/cascading is never asserted as verified without manufacturer coordination data.

Fault-current profileI''k and natural ip by node

Calculate a fault to plot the node profile.

Current limitationNatural peak vs entered cut-off point

Calculate to evaluate entered current-limiting data.

Cable thermal energyAdiabatic k²S² check against entered/estimated fault energy

Calculate to evaluate cable thermal energy.

Verification required: Results are calculation aids and are not guaranteed to be error-free or suitable for a specific project. Independently verify inputs, outputs, applicable standards, manufacturer data and project requirements before design release, procurement or installation.