Electrical Systems

Three Phase Configurations

Load Connected in Star with Neutral Conductor

Line Voltages

Vab  =  Dummy Text Dummy Text °  V Vbc  =  Dummy Text Dummy Text °  V Vca  =  Dummy Text Dummy Text °  V
Load Impedances Dummy Text Dummy Text Dummy Text
Line Currents Ia  =  Dummy Text Dummy Text °  A Ib  =  Dummy Text Dummy Text °  A Ic  =  Dummy Text Dummy Text °  A

Complex Power

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Neutral Current

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In three phase circuit the source as well as load can both be connected either in star or delta. Here the source is star connected. The delta connected source is rarely used in practice.

  • Here all the three phase configurations are solved considering ABC phase sequence.

  • In all the configurations the source is star connected and balanced. Van is taken as reference. Hence the line voltages are, Vab= |Vl|∠30° Vbc= |Vl|∠-90° and Vca= |Vl|∠-210°.

  • Although here it is shown star connected source, actually for load side analysis mainly the source side line voltages and phase angles matter irrespective of star or delta connected source. The star or delta connection at source side decides the voltage and current rating of the source winding.

  • If the load is star connected with neutral conductor and Zl = 0 & Zn = 0 then the individual phases can be analysed. In addition if the load is balanced then solution of one phase can be extended to the other phases for obtaining balanced line currents. When balanced the total power will be thrice of power consumed in one phase. Similarly for the delta connected load.

  • For star connected balanced load the current in the neutral conductor is zero. So the neutral conductor can be removed without disturbing the line currents or power consumed in the load.

  • In general any three phase system star or delta connected with or without line/neutral impedance, can be solved by applying Kirchhoff law or Maxwell loop method. The process further simplifies if the delta connected load is transformed to equivalent star or Y connection.