EEE 360 Energy Conversion and Transport

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

2. Lecture 10 360 Chapter 5 Transformers

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

4. 5.3.1 Ideal Transformer 360 Chapter 5 Transformers

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 5.23 Current, voltages and flux in an unloaded ideal transformer 360 Chapter 5 Transformers

6. Transformers 5.3.1 Ideal transformer • Loaded transformer Figure 5.24 Currents and fluxes in a loaded ideal transformer 360 Chapter 5 Transformers

7. Transformers 5.3.1 Ideal transformer • Turn ratio is: • The input and output complex powers are equal 360 Chapter 5 Transformers

8. Transformers 5.3.1 Ideal transformer Figure 5.25 Equivalent circuit of an ideal transformer 360 Chapter 5 Transformers

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 360 Chapter 5 Transformers

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 360 Chapter 5 Transformers

11. 5.3.2 Real transformer Transformer 360 Chapter 5 Transformers

12. Transformers 5.3.1 Real transformer Figure 5.30 Leakage flux in the real transformer 360 Chapter 5 Transformers

13. Transformers Figure 5.31 Equivalent circuit of a real transformer 360 Chapter 5 Transformers

14. Transformers Figure 5.32 Modified equivalent circuit of a real transformer 360 Chapter 5 Transformers

15. 5.3.4 Determination of transformer parameter by measurement 360 Chapter 5 Transformers

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 360 Chapter 5 Transformers

17. Transformers Short Circuit Test Figure 5.35 Equivalent circuit for short circuit test, measurement at the secondary side Figure 5.36 Simplified equivalent circuit for short circuit test 360 Chapter 5 Transformers

18. Transformers 5.3.1 Short Circuit Test Primary and secondary impedances are combined Figure 5.37 Simplified circuit for calculation of series impedance 360 Chapter 5 Transformers

19. Transformers Short circuit test evaluation 360 Chapter 5 Transformers

20. Transformers Open circuit test Figure 5.38 Equivalent circuit for open circuit test, measurement at the primary side. Figure 5.39 Simplified equivalent circuit 360 Chapter 5 Transformers

21. Transformers Open circuit test evaluation 360 Chapter 5 Transformers

22. Transformers Equivalent circuit obtained by measurement Figure 5.40 Equivalent circuit for a real transformer resulting from the open and short circuit tests. 360 Chapter 5 Transformers

23. Exercises using MAT CAD 360 Chapter 5 Transformers