ELECTRICAL NETWORK ANALYSIS

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Akash Thahrani• K-13ME05

Mehran university of engineering & technology• Shaheed Z A Bhutto campus Khairpur Mir’s

Introduction to Single-Phase

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Defination A single-phase electric power supply is the

distribution of alternating current electric power where all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors. A single-phase power supply has two hot legs or conductors, which have a sine wave that are 180 degrees apart.

Single-phase comes to the home with two wires: active and neutral. The neutral wire is connected to earth (water pipe, earth stake, etc.) at the switchboard.

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Introduction to Three-Phase

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Definitions

4 wires› 3 “active” phases, A, B, C› 1 “ground”, or “neutral”

Color Code› Phase A Red› Phase B Black› Phase C Blue› Neutral White or Gray

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Basic Three-Phase Circuit

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What is Three-Phase Power?

Three sinusoidal voltages of equal amplitude and frequency out of phase with each other by 120°. Known as “balanced”.

Phases are labeled A, B, and C. Phases are sequenced as A, B, C

(positive) or A, C, B (negative).

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Three-Phase Power

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How are the sources connected?

(a) shows the sources (phases) connected in a wye (Y).› Notice the fourth

terminal, known as Neutral.

(b) shows the sources (phases) connected in a delta (∆).

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