Two three-phase transformers are realized using single-phase transformers as shown in the figure. The phase difference (in degree) between voltages V₁ and V₂ is _______.

A balanced (positive sequence) three-phase AC voltage source is connected to a balanced, star connected load through a star-delta transformer as shown in the figure. The line-to-line voltage rating is 230 V on the star side, and 115 V on the delta side. If the magnetizing current is neglected and $${\overline{\mathrm I}}_\mathrm s=100\angle0^\circ$$, then what is the value of $${\overline{\mathrm I}}_\mathrm p$$ in Ampere?

For a single phase, two winding transformer, the supply frequency and voltage are both increased by 10%. The percentage changes in the hysteresis loss and eddy current loss, respectively are

The parameters measured for a 220V/110V, 50 Hz, single-phase transformer are:

Self inductance of primary winding = 45 mH
Self inductance of secondary winding = 30 mH
Mutual inductance between primary and secondary windings = 20 mH

Using the above parameters, the leakage (L_l1 , L_l2) and magnetizing (L_m) inductances as referred to primary side in the equivalent circuit respectively, are