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ElecToolsHQ

Primary Current Calculator

Calculate a transformer's primary current from its kVA rating and primary voltage (Ip = (kVA × 1000) ÷ Vp).

Formula

Ip = (kVA × 1000) ÷ Vp

Ip
Primary current, in amps
kVA
Transformer rating, in kilovolt-amps
Vp
Primary voltage, in volts

What this calculator does

Calculates the current drawn on a transformer's primary winding from its kVA rating.

Use cases

  • Size primary-side conductors and protection for a transformer
  • Check expected primary current against a measured reading
  • Estimate upstream demand from a transformer's kVA rating

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