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Different connections of windings in transformers

  • Different connections of windings in transformers

    In general, building distribution transformers are star- connected on the low voltage side to eliminate circulating triplen harmonics (3rd, 9th, 15th etc.) in a delta-connected three-phase winding. The high voltage side is almost always delta connected.

     

    There are many possible variations of winding connections of transformers. These variations can affect the magnitude of the voltages but more particularly they change the phase shift between the primary and secondary windings. There are about 20 different connections possible if the use of zig- zag earths on transformers with delta windings is included, but the most common winding connections for standard distribution transformers are:

    • DY11
    • DY1
    • DY5
    • DY7

     

    DY11 is the most commonly used connection for distribution transformers: it gives a 30o phase shift between primary and secondary. See Fig. 8 for the corresponding vector diagrams and an explanation of phase shift symbols and phase shift values.

    In general, building distribution transformers are star- connected on the low voltage side to eliminate circulating triplen harmonics (3rd, 9th, 15th etc.) in a delta-connected three-phase winding. The high voltage side is almost always delta connected.

     

    There are many possible variations of winding connections of transformers. These variations can affect the magnitude of the voltages but more particularly they change the phase shift between the primary and secondary windings. There are about 20 different connections possible if the use of zig- zag earths on transformers with delta windings is included, but the most common winding connections for standard distribution transformers are:

    • DY11
    • DY1
    • DY5
    • DY7

     

    DY11 is the most commonly used connection for distribution transformers: it gives a 30o phase shift between primary and secondary. See Fig.  for the corresponding vector diagrams and an explanation of phase shift symbols and phase shift values.

     

    Reference:  ELEC9713 Industrial and Commercial Power Systems

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