Enter any two known values across primary and secondary voltage and turns — the rest solve automatically using the turns ratio relationship.
An ideal transformer relates primary and secondary voltage to the number of turns on each winding. The voltage ratio follows the turns ratio.
Vp / Vs = Np / Ns, where Vp and Vs are primary and secondary voltages and Np and Ns are the corresponding winding turns.
If a transformer has 230 V on the primary and 23 V on the secondary, the voltage ratio is 10:1. If the secondary has 100 turns, an idealized calculation gives about 1,000 primary turns.
Real transformers have winding resistance, leakage reactance, losses and voltage regulation. Therefore, measured load voltage may differ from the ideal turns-ratio calculation. Never use the calculator alone to determine safe operating limits.
Does a step-up transformer increase current? Ideally, increasing voltage reduces available current for the same apparent power, subject to transformer losses.
Can two voltage values determine the ratio? Yes. Vp/Vs directly gives the ideal voltage ratio.
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