22. The total power consumed by a balanced three-phase load is 3, 000 Watts at 80 % power factor. Two wattmeters WA and WB are connected to the line. What is the reading of WA?
A. 2, 150 Watts B. 2, 000 Watts C. 1, 500 Watts D. 2, 500 Watts
REE - September 2008
23. In a balanced three-phase 230 V circuit, the line current is 90 A. The power is measured by two-wattmeter method. If the power factor is 100 % and the line current is the same, what is the reading on each wattmeter?
A. 25.6 kW B. 30.4 kW C. 17.9 kW D. 20.7 kW
24. The two-wattmeter method is applied to a three-phase, three-wire, 100 V, ABC system with the meters in lines B and C, WB = 836 Watts and WC = 224 Watts. What is the impedance of the balanced delta-connected load?
A.10∠45° Ω B. 10∠ - 45° Ω C. 20∠ - 45° Ω D. 20∠45° Ω
REE - September 2009
25. A three-phase, wye-connected system with 240 V per phase is connected to three loads: 10 ohms, 18.79 + j6.84 ohms, 9.83 - j6.88 ohms to phases A, B, and C, respectively. Find the current in phase C with phase sequence ACB.
A. 1.74 + j19.92 A B. -1.74 + j19.92 A
C. -1.74 - j19.92 A D. 1.74 - j19.92 A
26. Three impedances Zab = 4 - j3 ohms, Zbc = 3 + j4 ohms, and Zca = 10 + j0 ohms are connected in delta across a 220 Volts, three phase balanced source. The total power of the circuit is __________.
A. 1, 839 W B. 18, 392 W C. 1, 936 W D. 1, 849 W
27. A three-phase, four-wire system has the following unbalanced loads: Za = 10 + j10 Ω , Zb = 13 - j2 Ω , Zc = 7.5 + j10 Ω . Determine the total power delivered to the load if the line voltage is 208 V.
A. 4.48 kW B. 1.48 kW C. 2.49 kW D. 2.90 kW
REE - April 2005
28. A 3-phase 4-wire system has the following unbalanced loads: Z1 = 10 + j5 Ω , Z2 = 8 + j4 Ω , and Z3 = 20 + j0 Ω . The line to neutral voltage of the system is 120 Volts. What is the reading of the wattmeter in watts in Z3?
A. 900 B. 720 C. 1, 000 D. 1, 050