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Power System AnalysisLecture 33-Phase system

By

Nur Diyana Kamarudin

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Three Phase system Most countries use a,b, and c to denote the phases;

however R(Red), Y(Yellow) and B(Blue) is often alsoused.

Type of winding connection is called; Wye/star

connection and delta connection.

With the Wye system, the phase currents are equal tothe current in the lines.

The four wire system is of particular use for low voltagedistribution networks in which consumers aresupplied with a single-phase supply taken between aline and neutral.

This supply is often 230V or 240V and the line voltage is

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Balanced 3-phase system

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Balanced 3- No neutral current

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Advantages of 3 power

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Three phase- Wye connection

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Wye connection Line Voltages-PhasorDiagram

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Wye Connection, ctnd

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Delta Connection

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Three Phase example

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Three Phase example, ctnd

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Delta-Wye Transformation

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Delta-Wye Transformation proof

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Delta-Wye Transformation, ctnd

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Three Phase Transmission Lines