Chapter 3

Phasors and Polarity

3.1 Introduction

Phasors and polarity are two important and useful tools in power system protection. They aid in understanding and analyzing the connections, operation, and testing of relays and relay systems. In addition, these concepts are essential in understanding power system performance during both normal and abnormal operation. Thus, a sound theoretical and practical knowledge of phasors and polarity is a fundamental and valuable resource.

3.2 Phasors

The IEEE Dictionary (IEEE 100) defines a phasor as “a complex number.” Unless otherwise specified, it is used only within the context of steady-state alternating linear systems. It continues: “the absolute value (modulus) of the complex number corresponds to ...

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