Engineering calculator
Transformer secondary fault current
Three-phase symmetrical fault current at transformer secondary terminals, with optional source impedance.
Inputs
Results
- Fault current (infinite source)
- 26.67kA
- Fault current (with source)
- 24.69kA
- Fault level
- 18.52MVA
Isc = V / (√3 × (Zt + Zs)), Zt = Z% × V² / S, Zs = V² / Ssource
Safety-critical result — professional verification required
This is a screening estimate. It must not be used for design, equipment selection, protection settings or PPE without verification by a suitably qualified and competent engineer using a full study.
Assumptions
- Symmetrical RMS bolted three-phase fault
- Impedances added arithmetically (conservative)
- No motor contribution
Limitations
- Not a substitute for a full short-circuit study to IEC 60909
- Excludes DC offset / peak make current
- Earth-fault levels require sequence impedances
References: IEC 60909-0 · AS/NZS 3000
Provided for general information. Gridlinks Solutions accepts no liability for decisions made using this calculator without independent engineering verification.
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