T 2(3T₂(4)Machine 1FLYMachine 2Krossy147YAFor the three-phase power system with single-line diagram, equipment ratings and per-unitreactances are given as follows:Machines 1 and 2: 120 MVA, 10.5 kV, X = X2 = 0.2, X₁ = 0.03, X = 0.03;Transformers 1 and 2: 120 MVA, 11D/115Y kV, X₁= X2 = X0 = 0.05.Select a base of 120 MVA, 115 kV for the transmission line. On that base, the series reactances ofthe line are X1 X2 = 0.3 and Xo = 2X1 per unit. With a nominal system voltage of 115 kV at bus 3,machine 2 is operating as a motor drawing 40 MVA at 0.8 power factor lagging. Compute thefault current for single-line-to-ground fault at bus 3

Step 1: Step 2: Step 3: Step 4:

Answered: T 2 (3 T₂ (4) Machine 1 FLY Machine 2…

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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Three single-phase distribution transformers, each rated for 18 kVA, 20000/220 volts, are connected in a Dy three-phase bank. For convenience, at the factory, the OCT and the SCT were per- formed as per standards with the whole three-phase bank already connected and the measured values were as follows: Vline 381.051V, line 1.78436A, P30 = 372.414 W. Vline = 5656.85 V, Iline = 1.55885 A, P30 = 2160 W. Three phase bank of single phase transformer on a utility pole. 37.5 K (a) Find the single phase equivalent circuit referred to the low volt- age side. (b) Find the transformer regulation at the rated load and voltage and a power factor of 0.45 lagging (Neglect the excitation current). (c) Using the "load" model, what is the approximate transformer- bank's efficiency, n, under these conditions of load? (a) R2 X=2 Rsc=mXsc = mS (b) Vreg= (c) n = %
Two single phase transformers A and B with equal turns ratio have reactance of j3.2 and j19.2 referred to secondary. When operated in parallel, the load sharing of 100 kW at 0.8 pf lag between A and B transformers would respectively be a) 75 kw and 25kw b) 60 kw and 40 kw c) 20 kw and 80 kw d) 25 kw and 75 kw
8
3.8. Three identical 9-MVA, 7.2-kV/4.16-kV, single-phase transformers are con- nected in wye on the high-voltage side and delta on the low voltage side. The equivalent series impedance of each transformer referred to the high-voltage side is 0.12 + j0.82 S per phase. The transformer supplies a balanced three- phase load of 18 MVA, 0.8 power factor lagging at 4.16 kV. Determine the line-to-line voltage at the high-voltage terminals of the transformer.
2.5.3 A three phase power system has two generator connected in parallel to a transformer and subsequently to a 230 kV transmission line. The ratings for the components are given as below: Generator 1:10 MVA, reactance of 12%. Generator 2: 5 MVA, reactance of 8%. Transformer: 15 MVA, reactance of 6% Transmission line: impedance of 4+j60 2, for which the reactances in percentage are based on the ratings of the respective components. Obtain the reactance and impedance values of the components in the system in percentage, based on 15 MVA and rated voltage of the components.
1. A single-phase power system as shown in Figure 1 consists of a 240 V, 60 Hz generator supplying a load, Zod = 8 + j6 Q through a transmission line of impedance, Zne = 0.08 + j0.14 Q. Answer the following questions: (1) transformer, T; and T2. Determine the voltage at the load and transmission line losses without the (ii) Determine the voltage at the load and transmission line losses with the transformer, T, and T2. T1 T2 1:10 10:1 IG Zaine Zioad source Figure 1
A 4-bus three-phase power system consists of the following equipment: • Generator 1 connected to bus 1 with a rated power of 20MVA, rated voltage of 20 kV, and a series reactance of 0.4 p.u. • Generator 2 connected to bus 5, with a rated power of 12MVA, rated voltage of 10 kV, and a series reactance of 0.3 p.u. Transformer 1 connected between buses 1 and 2, is wye-wye connected with a rated power of 20 MVA, rated voltages 20/100 kV, and a series reactance of 0.1 p.u. • Transformer 2 connected between buses 4 and 5, is wye-wye connected with a rated power of 12 MVA, rated voltages 12/110 kV, and a series reactance of 0.15 p.u. • Transmission Line 2-3 connects buses 2 and 3 and had a series impedance of 50 + j75 ohms. • Transmission Line 3-4 connects buses 3 and 4 and had a series impedance of 40 + j80 ohms. • Load A connected to bus 3 and abosorbes20 MW and 10 MVAR. The voltage at bus 3 is 105 kV. 1) Draw the one-line diagram for the system. 2) Draw the per-unit, per phase…
6. In figure below the rating of reactance and various components are shown. A load of 50MW at p.f. lagging is taking from the 33kv substation which is to be maintained at 30kv. Calculate the terminal voltage of the synchronous machine (Vs) in pu, also represent the line and transformer in series reactance. The system is three phase system V6 11 kV 132 kV 132 kV 33 kV 50 MW Line 0.8 p.f. lagging j1000 50 MVA X 10% 50 MVA X 12% 30 kV
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.

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