A balanced three phase circuit is characterized as follows: Y-A connected; Source voltage in the b-phase is 150<135° V; Source phase sequence is negative sequence; Line impedance is 2+j3 2/4; Load impedance is 129+j171 /. a) Draw the single phase equivalent of the a-phase. b) Calculate the a-phase line current. c) Calculate the a-phase line voltage for the three phase load. d) Total power dissipated in the three phase load.

An unbalanced three-phase wye-connected and grounded load is connected to a balanced three- phase four-wire source. The load impedances Z, Z,, and Z, are given as 70 230°, 85L-40°, and 50 235° 2/phase, respectively, and the phase a line voltage has an effective value of 13.8 kV: use the line-to-neutral voltage of phase a as the reference and determine the following: The total power aelivered to the loads. 1025.795 kW 1035.795 kW 1055.795 kW None

An unbalanced three-phase wye-connected and grounded load is connected to a balanced three- phase four-wire source. The load impedances Z, Z, and Z, are given as 70 230°, 85 L-40°, and 50 235° 2/phase, respectively, and the phase a line voltage has an effective value of 13.8 kV: use the line-to-neutral voltage of phase a as the reference and determine the following: The line and neutral currents. 113.823 L-450 93.737 L-000 150.353 L-2700 113.823 L-60° 93.737 L-000 159.353 L-2850 113.823 L-300 93.737 L-800 150.353 L-275o None

2. A three-phase transmission line has parameters Xc-6 k 2, R-3.25 2 and X₁-25 92, and delivers 300 MW to a load with both ends of the line at 230 kV. Draw a pi equivalent per-phase circuit of the line. On a per-phase basis, calculate the active power delivered to the load, the reactive power of the line and the active power delivered by the source. Based on these calculations can the equivalent circuit be simplified further?

In a three-phase system the per-unit phase voltages are 100° , Vôn = 0.8Z180° Van 0.920° , Von = 0.92 - а What are the per-unit symmetrical components V0) and V)? Express in polar notation.

A three phase system cannot be obtained using two single phase source.  True  False

In Figure 1, the 3-phase source has a line-to-line voltage of 440 volts. The details of the impedances are the following: Z₁ = 36-j15; Z₂ = 40 + /300; Z₂ = 45+j60 ; Z₂ = 75 + jo ; Z5 = 50+j50; Z6 = 20+ j48 2. Determine the following: (a) Line currents: labi, and I (c) Line currents: lar, Ibr, and ICT; (b) Line currents: Iaz, Ibz, and Iczi (d) PT, QT, ST, and pft for the system; (e) W, and W, readings for 2-wattmeter method at lines a and b. Balanced 3-Phase ab-bc-ca source C Figure 1 →laT -Ibr -KT 1 lal ²3 ↓ Ibi 1 Ici la2 lb2 le2ܝ 150 1²₂ OND

The two three-phase loads in the figure are symmetrical. The first load (denoted with index 1) is Y-connected and the second load (denoted with index 2) is D-connected load. a) Determine the corresponding line current ID2 in the delta-connected load b) Determine the active current components: - of the IY1 current c) Determine the reactive current components: - of the IY1 current d) Calculate the total current IL , with which they load the feeding network e) Calculate theresulting cosφ

In a three-phase system, the per-unit symmetrical components of the phase currents are I0 = 0.5 , I9) = 120 , 12) = 0 What are the per-unit phase currents Ia, Ib, Ic? Express in polar notation.

Note: It is expected from student to develop impedance matrices ofthree phase power system. Develop impedance matrix (Z-bus) of power system network as shown in figure. [Values are given in per unit impedance.] j3 000 j2 14 12 j3 [000