A 20-MVA, 13.8-kV generator has a direct-axis subtransient reactance (X") of 0.25 per unit. The negat and zero-sequence reactances are, respectively, 0.35 and 0.10 per unit. The neutral of the generator is solidly grounded. Determine: 1. The subtransient current in the generator when a three-phase fault occurs at the generator terminals. 2. The subtransient current in the generator when a single line-to-ground fault occurs at the generator terminals.

A 20-MVA, 13.8-kV generator has a direct-axis subtransient reactance (X") of 0.25 per unit. The negat and zero-sequence reactances are, respectively, 0.35 and 0.10 per unit. The neutral of the generator is solidly grounded. Determine: 1. The subtransient current in the generator when a three-phase fault occurs at the generator terminals. 2. The subtransient current in the generator when a single line-to-ground fault occurs at the generator terminals.

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

Synchronous Generator

In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.

Salient Pole Rotor

Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.

Question

A 20-MVA, 13.8-kV generator has a direct-axis subtransient reactance (X") 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.
Determine:
1. The subtransient current in the generator when a three-phase fault occurs at the generator
terminals.
2. The subtransient current in the generator when a single line-to-ground fault occurs at the
generator terminals.

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Step 2: 1.Find the Sub-transient current for 3 phase fault.

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Step 3: 2. Find the Sub-transient current for SLG fault.

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