Transformer Inrush - Ip Estimate

Transformer energising inrush current 6–12× rated - basis for relay pickup and breaker withstand.

TransformerInrushProtection

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

I_{inrush} = k \cdot I_n

Symbol	Meaning	Unit
$I_n$	Rated current	A
$k$	Inrush multiplier

Source: IEEE C57.91

Transformer energising inrush current 6\u201312\u00d7 rated - basis for relay pickup and breaker withstand.