**Answer:**

**Given Data:**
- Alternator rating: 500 KVA
- Voltage rating: 1100 V
- Frequency: 50 Hz
- Connection: Y-connected
- Stator resistance: 0.1 Ω/phase
- Synchronous impedance: 1.5 Ω/phase
- Load power factor: Unity (1)

**Induced EMF per Phase:**

The induced EMF per phase can be calculated using the formula:

E = V + I(Zs + Rs)

Where,
E = Induced EMF per phase
V = Voltage rating per phase (line voltage/√3)
I = Load current per phase
Zs = Synchronous impedance per phase
Rs = Stator resistance per phase

Since the alternator is supplying full load at unity power factor, the load current per phase can be calculated using the formula:

I = S / (V * √3)

Where,
S = Apparent power (500 KVA)
V = Voltage rating per phase (1100 V)

Substituting the values, we get:

I = 500000 / (1100 * √3)
I ≈ 268.12 A

Substituting the values of V, I, Zs, and Rs into the induced EMF formula, we get:

E = 1100 + 268.12 * (1.5 + 0.1)
E = 1100 + 268.12 * 1.6
E ≈ 1544.48 V

Therefore, the induced EMF per phase for this condition is approximately 1544.48 V.

**Explanation:**

- The alternator rating of 500 KVA represents the maximum power that the alternator can supply.
- The voltage rating of 1100 V indicates the line-to-line voltage of the alternator.
- The frequency of 50 Hz represents the number of cycles per second the alternator produces.
- The Y-connected 3-phase alternator has its windings connected in a Y-shaped configuration.
- The stator resistance of 0.1 Ω/phase represents the resistance of each phase winding in the stator.
- The synchronous impedance of 1.5 Ω/phase represents the impedance of each phase winding in the stator.
- The alternator is supplying full load at unity power factor, which means the load is purely resistive.
- The induced EMF per phase is calculated using the formula E = V + I(Zs + Rs), where V is the voltage rating per phase, I is the load current per phase, Zs is the synchronous impedance per phase, and Rs is the stator resistance per phase.
- The load current per phase is calculated using the formula I = S / (V * √3), where S is the apparent power and V is the voltage rating per phase.
- Substituting the values into the formulas, we can calculate the induced EMF per phase as approximately 1544.48 V.