Let's go through the problem based on the image you've uploaded:

Problem Overview:

The problem involves a transformer bank setup, where the primary is on the right side, and the voltage sources are in a positive sequence. The voltage across the primary is $V_{ab} = 13.8 \, \text{kV} \angle 0^\circ$. The transformer banks consist of single-phase transformers with an impedance $X_I = 1.0 \, \Omega$ (on the primary side), and the turns ratio of the transformer is given as $n = \frac{N_2}{N_1} = 10$.

Tasks:

(1) Per-phase circuit diagram with the transformer turns ratio noted:

• This requires a simplified per-phase circuit, where the turns ratio $n = 10$ needs to be indicated on the transformer model.
• The transformer has a Δ-Y (delta-wye) connection, so we need to reduce it to an equivalent per-phase circuit.

(2) Per-phase per-unit circuit diagram:

• Here, we're asked to convert the values into per-unit system. The base quantities for the left side (primary) are given as:
  • Voltage Base: $\sqrt{3} V_{\text{L-L}}$
  • Power Base: $3 \, \text{W}$ (total for the three-phase system).

I can proceed by drawing the equivalent per-phase circuit and calculating the per-unit values. Would you like me to walk through the solution step by step, including the per-unit system calculation?