Transformer Turns Ratio Calculator

The primary winding full load current is calculated using the formula: Ip = S / (√3 × Vp) for three-phase transformers, or Ip = S / Vp for single-phase transformers, where S is the transformer rating and Vp is the primary voltage.

The secondary winding full load current is calculated as: Is = S / (√3 × Vs) for three-phase transformers, or Is = S / Vs for single-phase transformers, where S is the transformer rating and Vs is the secondary voltage.

The turns ratio is calculated as the ratio of primary voltage to secondary voltage: Turns Ratio = Vp / Vs. This ratio also equals the ratio of primary turns to secondary turns (Np:Ns).

A step-up transformer increases voltage from primary to secondary (turns ratio > 1), while a step-down transformer decreases voltage (turns ratio < 1). The type is determined by comparing primary and secondary voltages.

Voltage units (V, kV, MV) must be consistent in calculations. The calculator automatically converts units to ensure accurate results. Always verify that primary and secondary voltages are in appropriate units for your application.

Single-phase and three-phase transformers use different current calculation formulas. Three-phase calculations include the √3 factor, while single-phase calculations do not. This significantly affects the full load current results.

Choose VA for small transformers (under 1000 VA), kVA for medium transformers (1-1000 kVA), and MVA for large power transformers (above 1000 kVA). The rating represents the apparent power capacity of the transformer.

Turn ratio calculations are highly accurate for ideal transformers. In real transformers, small variations may occur due to factors like winding resistance, leakage inductance, and core losses, but the calculated ratio provides an excellent approximation.