Problem + Hard 83-1    Source:  Question 2 of the 2nd exam of the School of Engineering - UFRGS - 1976.

In the Figure 83-1.1 the circuit is symmetrical, balanced and the phase sequence is inverse or BCA. It is known that the line voltage V_CB = 500∠0° V and the current I_A = 8.66∠65° A. Furthermore, it is known that V₁ = 450 V and V₂ < |V_CB|. Determine:

a) phase currents.

b) the values ​​of r, X₁ and X ₂.

c) the phase of V₁.

Problem + Hard 83-2    Source:  Question 3 of the 2nd exam of the School of Engineering - UFRGS - 1975.

In Figure 83-2.1 the circuit is symmetrical, balanced and the phase sequence is direct or ABC. It is known that V₁ = 346.1 V,   V₂ = 200 V   and   A = 20 A.   Determine:

a)  the values ​​of R, X and the line voltage.

b)  the power factor of the star circuit.