A salient-pole generator without dampers is rated 20 MVA, 13.8 KV and has a direct-axis subtransient reactance of 0.25 per unit. The negative- and zero-sequence reactances are, respectively, 0.35 and 0.10 per unit. The neutral of the generator is solidly grounded. With the generator operating unloaded at rated voltage with E= 1/0° per unit, a single line-ta-ground fault occurs the machine terminals, which then have the following per unit voltages to ground: %3D an V=0; V= 1.013/-102.25 ;V= 1.013/102.25 park. Now, For subtransient conditions due the fault: 12, The negative sequence current in p.u is:

A salient-pole generator without dampers is rated 20 MVA, 13.8 KV and has a direct-axis subtransient reactance of 0.25 per unit. The negative- and zero-sequence reactances are, respectively, 0.35 and 0.10 per unit. The neutral of the generator is solidly grounded. With the generator operating unloaded at rated voltage with E= 1/0° per unit, a single line-ta-ground fault occurs the machine terminals, which then have the following per unit voltages to ground: %3D an V=0; V= 1.013/-102.25 ;V= 1.013/102.25 park. Now, For subtransient conditions due the fault: 12, The negative sequence current in p.u is:

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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Concept explainers

Fault Analysis

In an electrical engineering system, a fault is an abnormal electric current flowing through the system, and fault analysis is the study of these faults. For instance, a short-circuit is a fault where the live wire touches the ground or neutral wire. If a circuit is interrupted by a failure of a current-carrying wire then an open circuit fault occurs. The open-circuit faults are also called series faults. One or more phases or ground may be involved in a three-phase fault or may occur only between two phases. Current flows into the earth in case of a ground fault or earth fault. For most situations, the prospective short circuit current of a fault that is predictable can be calculated. To limit the loss of service because of a failure, the protective devices can detect fault conditions and operate circuit breakers and also other devices. All phases equally can be affected in a poly-phase system which is known as symmetric electrical fault. The asymmetric fault becomes more complicated to analyze if only some phases are affected. By using methods such as symmetrical components, the power system analysis of these types of faults is often simplified. The main objective of power system protection is to design, detect, and interrupt power system faults.

Question

A salient-pole generator without dampers is
rated 20 MVA, 13.8 KV and has a direct-axis
subtransient reactance of 0.25 per unit. The
negative- and zero-sequence reactances are,
respectively, 0.35 and 0.10 per unit. The neutral
of the generator is solidly grounded. With the
generator operating unloaded at rated voltage
with E = 1/0° per unit, a single line-ta-ground
fault occurs the machine terminals, which then
have the following per unit voltages to ground:
%3D
V,=0; V,- 1.013-102.25 ;V=
1.013/102.25
naik
Now, For subtransient conditions due the fault:
1,, The negative sequence current in p.u is:
Answer:

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