EEE 360 Energy Conversion and Transport

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# EEE 360 Energy Conversion and Transport - PowerPoint PPT Presentation

EEE 360 Energy Conversion and Transport. George G. Karady &amp; Keith Holbert Chapter 5 Transformers. Lecture 10. Transformers. Figure 5.22 Single phase transformer construction. 5.3.1 Ideal Transformer. Transformers. 5.3.1 Ideal transformer

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Presentation Transcript

EEE 360

Energy Conversion and Transport

George G. Karady & Keith Holbert

Chapter 5

Transformers

360 Chapter 5 Transformers

Lecture 10

360 Chapter 5 Transformers

Transformers

Figure 5.22 Single phase transformer construction

360 Chapter 5 Transformers

5.3.1 Ideal Transformer

360 Chapter 5 Transformers

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

Transformers

5.3.1 Ideal transformer

Figure 5.24 Currents and fluxes in a loaded ideal transformer

360 Chapter 5 Transformers

Transformers

5.3.1 Ideal transformer

• Turn ratio is:
• The input and output complex powers are equal

360 Chapter 5 Transformers

Transformers

5.3.1 Ideal transformer

Figure 5.25 Equivalent circuit of an ideal transformer

360 Chapter 5 Transformers

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

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

5.3.2 Real transformer Transformer

360 Chapter 5 Transformers

Transformers

5.3.1 Real transformer

Figure 5.30 Leakage flux in the real transformer

360 Chapter 5 Transformers

Transformers

Figure 5.31 Equivalent circuit of a real transformer

360 Chapter 5 Transformers

Transformers

Figure 5.32 Modified equivalent circuit of a real transformer

360 Chapter 5 Transformers

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

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

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

Transformers

Short circuit test evaluation

360 Chapter 5 Transformers

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

Transformers

Open circuit test evaluation

360 Chapter 5 Transformers

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