Question

For developing per-unit equivalent circuits of single-phase three-winding transformer, a common ${\mathit{S}}_{\mathbf{b}\mathbf{a}\mathbf{s}\mathbf{e}}$is selected for all three windings, and voltage bases are selected in proportion to the rated voltage of the windings.

(a) True

(b) False

Short answer

Answer

Therefore, the correct option is (a) True.

Step-by-step solution

 Check the statement for power base.

The MVA power base ($S_{base}$) for entire system is always common.

Suppose that, for an ideal transformer, HV is high-voltage side and LV is low voltage side.

For this HV and LV sides, the $S_{base}$will be same.

Check statement for voltages bases.

Single line diagram is drawn for the single-phase system, by converting the balanced three-phase system.

Consider, $V_{HV}$and $V_{LV}$are the rated voltage of HV and LV windings of transformer.

The base voltage for HV winding of transformer will be $H_{HV}$and for LV winding, the base voltage will be $V_{LV}$.

Therefore, the base voltages are selected in proportion to the rated voltage.

Hence, correct option is (a) True.