About The Short Circuit Current Estimator

The Short Circuit Current Estimator calculates transformer full-load current and an approximate three-phase fault current from transformer kVA, secondary voltage, and impedance percent.

How to Use the Short Circuit Estimator Online

1. Enter transformer rating in kVA.
2. Enter secondary line-to-line voltage and transformer impedance percent.
3. Run the estimator to see full-load current, fault current, and fault level.

Choosing Options Correctly

This is a transformer-terminal approximation. Utility source strength, cable impedance, motor contribution, X/R ratio, grounding, and protective-device standards need formal study for final design.

Common Use Cases

• Estimate available fault current early in a design.
• Check order-of-magnitude interrupting ratings.
• Compare transformer impedance scenarios.

Quick FAQ

Is this acceptable for arc-flash or protection studies?
No. It is a simplified estimate and does not replace a formal short-circuit, coordination, or arc-flash study.

Where is the fault assumed?
The result typically represents a simplified fault at the point described by the transformer and impedance inputs, before detailed feeder effects.

What details are missing?
Cable impedance, motor contribution, utility available fault current, transformer X/R ratio, grounding, and protective device behavior may be missing.

Can I use it to choose equipment SCCR?
Use it only as an early check. Final equipment ratings need a qualified study and applicable code requirements.