Question

A single-phase transformer is rated 110/440 V, 2.5 kVA. Leakage reactance measured from the low-tension side is 0.06 Ω. The per unit leakage reactance will be
1. 0.0062/unit
2. 0.0124/unit
3. 0.0496/unit
4. 0.1983/unit

Answer 1

Correct Answer - Option 2 : 0.0124/unit

p.u. value = Actual value/ base value

Z_base = V²/S

Voltage rating on low voltage side (V) = 110 V

VA rating (S) = 2.5 kVA

\({Z_{base}} = \frac{{{{110}^2}}}{{2500}}\)

Per unit value \( = \frac{{0.06 \times 2500}}{{{{110}^2}}} = 0.0124\)