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Protective Relaying, 4th Edition
book

Protective Relaying, 4th Edition

by J. Lewis Blackburn, Thomas J. Domin
February 2014
Intermediate to advanced
695 pages
21h 31m
English
CRC Press
Content preview from Protective Relaying, 4th Edition

2

Fundamental Units

Per-Unit and Percent Values

2.1 Introduction

Power systems operate at voltages for which kilovolt (kV) is the most convenient unit for expressing voltage. Also, these systems transmit large amounts of power, so that kilovolt-ampere (kVA) and megavolt-ampere (MVA) are used to express the total (actual or apparent) three-phase power. These quantities, together with kilowatts, kilovars, amperes, ohms, flux, and so on, are usually expressed as a per unit or percent of a reference or base value. The per-unit and percent nomenclatures are widely used because they simplify specification and computations, especially when different voltage levels and equipment sizes are involved.

This discussion is for three-phase electric systems ...

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Publisher Resources

ISBN: 9781439888124