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Transformer Inrush Current Calculator — Rated Amps & Energization Estimate

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Transformer rating (kVA) Use nameplate apparent-power rating.Energized winding voltage (V) Line-to-line voltage for three-phase.Transformer phase Inrush multiple (× rated current) Prefer manufacturer or study data; this is intentionally editable.

Calculated result

902.11 A estimated inrush

Rated current: 90.21 A

Entered inrush multiple: 10 × rated current

Equivalent energization apparent power: 750 kVA

This is a screening estimate, not a waveform peak, duration model, fault current or protective-device setting.

Show the working

1. Rated current = 75 × 1000 ÷ (√3 × 480) = 90.211 A.
2. Estimated inrush = 90.211 × 10 = 902.11 A.
3. Equivalent apparent power = √3 × 480 × 902.11 ÷ 1000 = 750 kVA.

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