9.1 The single-line diagram of a three-phase power system is shown in Figure 9.17. Equipment ratings are given as follows: Synchronous generators: GI 1000 MVA 15 kV G2 1000 MVA 15 kV G3 500 MVA 13.8 kV 13.8 kV G4 750 MVA Transformers: TI 1000 MVA T2 1000 MVA T3 500 MVA T4 750 MVA Transmission lines: 1-2 765 kV 1-3 765 kV 2-3 765 kV XX₂ = 0.18, X, -0.07 per unit X=X₂-0.20, X, 0.10 per unit XX₂ = 0.15, X, = 0.05 per unit X-0.30, X₂= 0.40, X, 0.10 per unit 15 kV A/765 kV Y 15 kV A/765 kV Y 15kV Y/765kVY 15 kV Y/765 kVY X = 0.10 per unit X = 0.10 per unit X = 0.12 per unit X= 0.11 per unit Χ = 50 Ω, X = 150 Ω X = 40 Ω, X = 100 Ω X = 100 Ω Χ, " 40 Ω, Line 1-3 Line 1-2 T₂ Line 2-3 The inductor connected to Generator 3 neutral has a reactance of 0.05 per unit using generator 3 ratings as a base. Find fault current occurs at bus 3 if: 1- L-G fault actual 2- L-L-G fault 3- L-L fault base. using a 1000-MVA, 765-kV base in the zone of line 1-2 25 ase والمسيرا FI Pr

9.1 The single-line diagram of a three-phase power system is shown in Figure 9.17. Equipment ratings are given as follows: Synchronous generators: GI 1000 MVA 15 kV G2 1000 MVA 15 kV G3 500 MVA 13.8 kV 13.8 kV G4 750 MVA Transformers: TI 1000 MVA T2 1000 MVA T3 500 MVA T4 750 MVA Transmission lines: 1-2 765 kV 1-3 765 kV 2-3 765 kV XX₂ = 0.18, X, -0.07 per unit X=X₂-0.20, X, 0.10 per unit XX₂ = 0.15, X, = 0.05 per unit X-0.30, X₂= 0.40, X, 0.10 per unit 15 kV A/765 kV Y 15 kV A/765 kV Y 15kV Y/765kVY 15 kV Y/765 kVY X = 0.10 per unit X = 0.10 per unit X = 0.12 per unit X= 0.11 per unit Χ = 50 Ω, X = 150 Ω X = 40 Ω, X = 100 Ω X = 100 Ω Χ, " 40 Ω, Line 1-3 Line 1-2 T₂ Line 2-3 The inductor connected to Generator 3 neutral has a reactance of 0.05 per unit using generator 3 ratings as a base. Find fault current occurs at bus 3 if: 1- L-G fault actual 2- L-L-G fault 3- L-L fault base. using a 1000-MVA, 765-kV base in the zone of line 1-2 25 ase والمسيرا FI Pr

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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8
Why do non-linear loads such as computers, electronic ballasts and welding machines cause a three-phase distribution system to have distorted waveforms known as harmonics?
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.
X 0.1j Z12 = 0.1 j Z23 = 0.1 j 0.2 j KAY 02) 0.1j Load 1 Load 2 Load 3 Consider the single line diagram shown in the figure. All impedances are expressed in per unit on a common 100 MVA base. The generator transient reactance =0.5 j. The Bus 1 prefault voltage (1 + 0.0 j). If a bolted three phase fault occur at bus 1. The magnitude of fault current is: Select one O a. 5.8 pu b. 7.5 pu c. less than 5.8 pu O d. 11.6667 pu e. greater than 12.0 pu
2) The power system consists of generators, motors, transformers, and transmission lines. The ratings are as follows: G1: 3-phase generator 25 MVA, 11 KV, X = 20% M1: 3-phase motor M2: 3-phase motor T1:3 single phase transformers T2: 3-phase transformer Line: 15 MVA, 13 KV, X = 25% 7.5 MVA, 13 KV, X = 25% Single phase transformer rating 30 MVA, 6.9/69 KV X = 10% Three phase transformer rating 30 MVA, 13.8/69 KV X = 10% Χ - 50 Ω = Τι G₁ 2. Line Figure 1. 3 T2 Σ M₁ Δι M2 Find the reactance (X) in p.u. units, given the base value of 25 MVA, 11 KV.
Q2\ The one-line diagram of a simple power system is shown in figure below. All impedances are expressed in per unit (pu) on a common MVA base. All resistances and shunt capacitances are neglected. The generators are operating on no load at their rated voltage. A three-phase fault occurs at bus 1 through a fault impedance of Zf = j0.08 per unit. Using Thevenin's theorem obtain the impedance to the point of fault and the fault current in per unit. Determine the bus voltages and line currents of generators during fault. X₁ = = 0.1 XT-0.1 3 1 to ojo XL=0.2 2 040 X₁ = 0.1
The steady-state voltage drop between the load and the sending end of the line seen in (Figure 1) is excessive Suppose that V-4950/0° V (rms). A capacitor is placed in parallel with the 192 kVA load and is adjusted until the steady-state voltage at the sending end of the line has the same magnitude as the voltage at the load end, that is, 4950 V (rms). The 192 kVA load is operating at a power factor of 0.8 lag. Part A Calculate the size of the capacitor in microfarads if the circuit is operating at 60 Hz. In selecting the capacitance, use the value that results in the lowest possible power loss in the line. Express your answer in microfarads to three significant figures. ▸ View Available Hint(s) Figure 1 of 1 202 1100 192 kVA 0.8 lag ΜΕ ΑΣΦ. 11 vec C= 22.8 Submit Previous Answers Incorrect; Try Again; 5 attempts remaining Provide Feedback ? F
In the following power system M ilio YA T₂ L47 YA 5 ΔΥ synchronous generators G₁,G₂ and synchronous motor M all have the same per-unit impedances Xo=0.05, X₁=X₂=0.7 The three transformers T₁, T₂, T3 are identical with X=0.1pu. Finally, the three transmission lines L47, L57, L67 are identical with per-unit impedances X₁=0.2, X₁=X₂=0.1 Pre-fault all voltages are 1 pu. Then the a phase at bus 6 faults to ground (through zero impedance). What is the magnitude of the per-unit fault current? उह 4 7 L 67 L 57 Y
Figure below shows a power system. The rating of generators and transformers are:G1:25MVA, 6.6KV, jO.2 p.u. G2:15MVA, 6.6KV, jo.15 p.u. G3:30MVA, 13.2KV, jo.15 p.u. T1: 30MVA, 6.6A- 115Y KV, jo.1 p.u.T2: 15MVA, 6.6A- 115Y KV, jo.1 p.u. T3:single phase units each rated 10MVA, 69/ 6.9 KV, jo.1 p.u. Find te reactances in p.u, take a base of 30MVA, 6.6 KV in the circuit of G1 .=.XG1 G2} 4 A lubu T2 T1 T3 G1 G3 j120 2 j90 N
For the system shown in figure, voltages V2, V3 and angles 82, 83 are calculated using Newton-Raphson method. shunt line charging admittances are neglected. All the values are given in per unit on 100MVA base. Calculate the complex power flows S12 and S32 in actual units. 1) Z12 = 0.01+ j0.02 Z3 = 0.02+ j0.04 PL G QL Slack bus V2 = 0.96L -1.67° V3 = 0.884 - 5.48° Vi=1.0/0° (estimated time to answer this question: 13 minutes)
Only need answers for the second question(9.16) at bus 1.
10. A three-phase transformer consists of a bank of single-phase transformers connected to form a Dd0 connection. A fault on one of the transformers causes it to be removed from the circuit, and the remaining two transformers are connected in an open-delta (V-V) connection. Show that the capacity of the open-delta connected transformers is 58% of the delta-connected transformers.