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 10
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3. Figure 5.22 Single phase transformer construction
Transformers
Figure 5.22 Single phase transformer construction
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360 Chapter 5 Transformers

4. 5.3.1 Ideal Transformer
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5. Transformers 5.3.1 Ideal transformer
Winding resistances are zero, no leakage inductance and iron loss
Magnetization current generates a flux that induces voltage in both windings
Fig Current, voltages and flux in an unloaded ideal transformer
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360 Chapter 5 Transformers

6. Transformers 5.3.1 Ideal transformer Loaded transformer
Figure Currents and fluxes in a loaded ideal transformer
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7. Transformers 5.3.1 Ideal transformer Turn ratio is:
The input and output complex powers are equal
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8. Figure 5.25 Equivalent circuit of an ideal transformer
Transformers
5.3.1 Ideal transformer
Figure Equivalent circuit of an ideal transformer
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9. Transformers 5.3.1 Ideal transformer
Transferring impedances through a transformer
Figure 5.26 Thévenin equivalents of transformer circuit
a) Original circuit with ideal
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10. Transformers 5.3.1.1 Transferring impedances through a transformer
Figure 5.26 Thévenin equivalents of transformer circuit
b) Equivalent circuit when secondary impedance is transferred to primary side and ideal transformer eliminated
(c) Equivalent circuit when primary source is transferred to secondary side and ideal transformer eliminated
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11. 5.3.2 Real transformer Transformer
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12. Transformers 5.3.1 Real transformer
Figure Leakage flux in the real transformer
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13. Transformers Figure 5.31 Equivalent circuit of a real transformer
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14. Transformers
Figure Modified equivalent circuit of a real transformer
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15. 5.3.4 Determination of transformer parameter by measurement
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16. Transformers
5.3.4 Determination of transformer parameter by measurement
Open circuit test
Provides magnetizing reactance and core loss resistance
Obtain components are connected in parallel
Short circuit test
Provides combined leakage reactance and winding resistance
Obtain components are connected in series
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17. Transformers Short Circuit Test
Figure Equivalent circuit for short circuit test, measurement at the secondary side
Figure Simplified equivalent circuit for short circuit test
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18. Transformers 5.3.1 Short Circuit Test
Primary and secondary impedances are combined
Figure Simplified circuit for calculation of series impedance
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19. Transformers Short circuit test evaluation 11/28/2018
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20. Transformers Open circuit test
Figure Equivalent circuit for open circuit test, measurement at the primary side.
Figure 5.39 Simplified equivalent circuit
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21. Transformers Open circuit test evaluation 11/28/2018
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22. Transformers Equivalent circuit obtained by measurement
Figure 5.40 Equivalent circuit for a real transformer resulting from the open and short circuit tests.
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23. Exercises using MAT CAD
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