1. Energy Conversion and Transport George G. Karady & Keith Holbert
EEE 360
Energy Conversion and Transport
George G. Karady & Keith Holbert
Chapter 5
Transformers
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360 Chapter 5 Transformers

2. Lecture 12
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360 Chapter 5 Transformers

3. 5.4 Three-phase transformer
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4. Transformers Figure 5.46 Very large three-phase network transformer.
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5. Transformers
Figure 5.47 A three-phase wye-delta transformer with three-legged iron core.
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6. Transformers Usual connections for three-phase transformers 11/12/2018
360 Chapter 5 Transformers

7. 5.4.1 Wye / Wye connection
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8. Transformers
5.41.Wye/wye
Figure Wye connected three-phase transformer
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360 Chapter 5 Transformers

9. Transformers
Figure Three-phase network supplies a load through a transformer.
Figure Equivalent circuit of the wye-wye transformer system of Figure 5.49.
Figure 5.51 Single-phase equivalent circuit for phase A of the three-phase wye-wye transformer system of Figure 5.50.
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10. 5.4.2 Wye / Delta connection
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11. Transformers Figure 5.52 Wye-delta connected transformer , 5.4.2
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12. Transformers
Figure Wye-delta connected transformer , currents and voltages
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13. Transformers
Figure Single-phase equivalent circuit of a wye-delta transformer.
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14. 5.4.3 Delta / Wye connection
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15. Transformers Figure 5.54 Delta-Wye connected transformer 11/12/2018
360 Chapter 5 Transformers

16. 5.4.4 Delta / Delta connection
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17. Transformers Figure 5.55 Delta-Delta connected transformer 11/12/2018
360 Chapter 5 Transformers

18. Table 5.1 Three-phase Transformer Relations
Transformers
Table 5.1 Three-phase Transformer Relations
Transformer Connection
Primary and Secondary Voltage Phase Relation
Phase Shift*
Windings Placed on the Same Leg
Wye-Wye
VAN is in phase with Van
Zero
A and a
Wye-Delta
VAN is in phase with Vab
30°
A and ab
Delta-Wye
VAB is in phase with Van
–30°
AB and a
Delta-Delta
VAB is in phase with Vab
AB and ab
* Note: Phase shift lead between line-to-line voltages, VAB and Vab, and line-to-neutral voltages, VAN and Van, and line currents, IA and Ia.
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360 Chapter 5 Transformers

19. 5.4.7 Equivalent circuit parameters
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20. Transformers
Figure Open circuit test for three-phase transformer parameter measurement
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21. Transformers
Open circuit test
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22. Transformers
Open circuit test
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23. Transformers
Figure Short circuit test for three-phase transformer parameter measurement
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24. Transformers
Short circuit test
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25. Transformers
Short circuit test
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26. Exercises using MAT CAD
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27. Transformers
Figure One-line diagram of delta-wye connected transformer supplies two balanced loads through a transmission line.
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