Transformer Current And Turn Ratio Calculator

Calculate primary and secondary full load currents, and turns ratio for single-phase or three-phase transformers.

Input Parameters

  • Transformer Rating: Maximum load capacity in VA, kVA, or MVA
  • Primary Voltage: Input voltage to the transformer
  • Secondary Voltage: Output voltage from the transformer
  • Phase Configuration: Single-phase or three-phase operation

Calculator Output

  • Primary Current: Current in primary winding (A)
  • Secondary Current: Current in secondary winding (A)
  • Turn Ratio: Primary to secondary voltage ratio

Transformer Equations

Turn Ratio:

\[a = \frac{N_1}{N_2} = \frac{V_1}{V_2} = \frac{I_2}{I_1}\]

Single-Phase Primary Current:

\[I_1 = \frac{S}{V_1}\]

Single-Phase Secondary Current:

\[I_2 = \frac{S}{V_2}\]

Three-Phase Primary Current:

\[I_1 = \frac{S}{\sqrt{3}V_1}\]

Three-Phase Secondary Current:

\[I_2 = \frac{S}{\sqrt{3}V_2}\]

Where:

  • \(a\): Turn ratio
  • \(N_1, N_2\): Number of turns in primary and secondary
  • \(V_1, V_2\): Primary and secondary voltages
  • \(I_1, I_2\): Primary and secondary currents
  • \(S\): Transformer rating (VA, kVA, or MVA)

Applications

Use this calculator to:

  • Design electrical circuits with transformers
  • Verify transformer operating limits
  • Prevent system overloads
  • Select appropriate transformers for your application
  • Ensure safety in electrical installations