Q1) A three-phase 1OMVA, 11 kV generator with a solidly earth neutral "solidly grounded", this generator supplies a feeder, the relative impedance(positive, negative and zero sequence) of the generator and the feeder are as follows: A fault from one phase to earth (SLG) occurs at the far end of the feeder, determine the voltage of the faulty phase at the terminal of the generator. Generator Feeder Positive sequence impedance(:1) Negative sequence impedance(22) Zero sequence impedance (ZO) j1.2 j1.0 jo.9 j1.0 j0.4 j3.0

Q1) A three-phase 1OMVA, 11 kV generator with a solidly earth neutral "solidly grounded", this generator supplies a feeder, the relative impedance(positive, negative and zero sequence) of the generator and the feeder are as follows: A fault from one phase to earth (SLG) occurs at the far end of the feeder, determine the voltage of the faulty phase at the terminal of the generator. Generator Feeder Positive sequence impedance(:1) Negative sequence impedance(22) Zero sequence impedance (ZO) j1.2 j1.0 jo.9 j1.0 j0.4 j3.0

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

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A three-phase, 100-MVA, 20-kV generator is connected to a three-phase, 100-MVA, 20-kV motor through a transmission line. The reactances of the generator and motor are 0.25 and 0.20 per unit, respectively. The line reactance is 0.10 per unit. The motor is taking 50 [MW] at 0.8 power factor leading at rated voltage. Suppose a three-phase short circuit occurs at the generator terminals, determine the transient currents in the generator and motor as well as the short-circuit current.
7. System Model and Per Unit T1 Line T2 BE 31.25miles 3 Impedance Load R1+jXL-0.1+j0.5 p.u. 30 MVA 30 MVA 13 kV X-0.1 p.u. 14 kV 13/220 kV X-0.2 p.u. 35 MVA * Transformer T2 is composed of "three single-phase" transformers, each rated 40/3 MVA, 132.8:14 kV with a leakage reactance of 0.1 per unit. (a) Fill in the appropriate base values. Gen. G Trans. Ti Line Trans. T: Load New MVA Base New KV Base (b) Calculate the impedance values. Gen G Trans. T1 Line Trans. T2 Load p.u. Impedance
A synchronous generator and motor are rated for 30,000 kVA, 13.2kV and both have sub-transient reactance of 20%. The line connecting them has a reactance of 10% on the base of machine ratings. The motor is drawing 20,000kW at 0.8 pf leading. The terminal voltage of the motor is 12.8kV. When a symmetrical three-phase fault occurs at motor terminals, find the sub transient current in generator, motor and at the fault point.
Three single-phase two-winding transformers, each rated 3 kVA, 220/110volts, 60 Hz, with a 0.10 per-unit leakage reactance, are connected as athree-phase extended D autotransformer bank, as shown in Figure 3.36 (c).The low-voltage D winding has a 110-volt rating. (a) Draw the positive sequencephasor diagram and show that the high-voltage winding has a479.5-volt rating. (b) A three-phase load connected to the low-voltageterminals absorbs 6 kW at 110 volts and at 0.8 power factor lagging. Drawthe per-unit impedance diagram and calculate the voltage and current atthe high-voltage terminals. Assume positive-sequence operation.
Figure shows a generator connected to a metropolitan system (infinite bus) through highvoltage lines. The numbers on the figure indicate the reactances in p.u. Breakers adjacent to afault on both sides are arranged to clear simultaneously. Determine the critical clearing anglefor the generator for a 3-phase fault at the point P when the generator is delivering 1.0 p.u.power. Assume that the voltage behind transient reactance is 1.2 p.u. for the generator andthat the voltage at the infinite bus is 1.0 p.u.
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A star connected neutral grounded 3-phase synchronous generator consists of 0.1 p.u of sub transient reactance ,0.3 p.u of transient reactance and 0.5 p.u of leakage reactance.The zero sequence reactance of the synchronous reactance is None of the above 0.5 p.u 0.7 p.u 0.6 p.u
A 3-phase generator (30 MVA, 13.8 KV, 0.15) supplies two motors (rated at 20 MVA, 12.8 KV, 20%, and 10 MVA, 12.8 KV, 20%, respectively) through a step-up transformer - transmission line - step- down transformer arrangement. The 3-phase transformers are rated at 35 MVA, 13.2 KV-A/115 KV-Y with 10 % leakage reactance. The line reactance is 80 ohms. Draw the equivalent per unit reactance diagram by selecting 30 MVA, 13.8 KV in the generator circuit. Also, calculate the current supplied by the source and the currents of each motor
A generator is connected through a 20 MVA, 13.8 / 138 kV step up transformer, to a transmission line. At the receiving end of the line a load is supplied through a step down transformer of 10 MVA, 138 / 69 kV rating. A 0.72 p.u. load, evaluated, on load side transformer ratings as base values of 10 MVA and 69 kV in load circuit, the value of the load (in per unit) in generator circuit will be
Q1. Three single-phase two winding transformers, each rated 400 MVA, 13.8kV/199.2kV, leakage reactance of 0.10 pu are connected to form a three phase transformer bank. Winding resistance and exciting current are neglected. The high voltage windings are star connected. A three-phase load operated under balanced positive sequence conditions on the high voltage side absorbs 1000 MVA at 0.9pf lagging, a phase voltage of 199.2/0°kV. Determine the phase voltage at the low voltage bus if the low-voltage windings are also star connected.
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