Problem 85-1    Source:   Adapted of the Example 11.6 - page 270 - NILSSON, James W. & RIEDEL, Susan A. - Book: Circuitos Elétricos- 5ª Edição - LTC Editora - 1999.

In the circuit of the Figure 85-01.1 we have V_fase = 120 V   and   Z_A = Z_B = Z_C = 8 + j6. Calculate:

a) The reading in the two wattmeters;

b) Check that the total power measured by wattmeters is equal to the power supplied to the load.

Problem 85-2    Source:   Adapted from the Exercise 11.13 - page 271 - NILSSON, James W. & RIEDEL, Susan A. - Book: Circuitos Elétricos- 5ª Edição - LTC Editora - 1999.

Use the two wattmeter reading of the previous problem to calculate the total reactive power received by the load.

Problema 85-3    Source:   Adapted from the Exercise 22.8 - page 677 - BOYLESTAD, Robert L. - Book: Introdução à Análise de Circuitos - 10ª Edição - Ed. Prentice Hall - 2008.

In the circuit shown in the figure below, V_AB = 208∠0°, V_BC = 208∠-120°, V_CA = 208∠120°, Z_AB = 10 Ω, Z_BC = 15 + j20 Ω and Z_CA =12 - j12 Ω. This unbalanced load, connected in the delta configuration, has two wattmeters connected as shown in the figure below. Find:

a)  the modulus and the angle of the phase currents.

b)  the modulus and the angle of the line currents.

c)  the reading of wattmeters.