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Transformer Voltage Regulation Calculator — Measured & R/X Method

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Calculation method Power-factor direction No-load secondary voltage (V) Comparable RMS voltage at the transformer secondary terminals.Loaded secondary voltage (V) Loaded RMS voltage at the same terminals.Resistance drop, %R Equivalent-circuit resistance drop in percent.Reactance drop, %X Equivalent-circuit reactance drop in percent.Load power factor Enter 0–1.Load (% rated) Approximation scales the full-load first-order result by load fraction.

Calculated result

4.545% regulation

Voltage change: 10 V

Positive regulation: secondary voltage falls from no-load to the entered loaded condition.

Measurement mode compares like-for-like RMS voltages at the same secondary terminals with primary voltage and tap position held constant.

Show the working

1. ΔV = 230 − 220 = 10 V.
2. Regulation = (230 − 220) ÷ 220 × 100 = 4.5455%.

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