EEE 360 Energy Conversion and Transport George G

EEE 360 Energy Conversion and Transport George G. Karady & Keith Holbert Chapter 5 Transformers 9/15/2020 360 Chapter 5 Transformers 1

Lecture 12 9/15/2020 360 Chapter 5 Transformers 2

5. 4 Three-phase transformer 9/15/2020 360 Chapter 5 Transformers 3

Transformers Figure 5. 46 Very large three-phase network transformer. 9/15/2020 360 Chapter 5 Transformers 4

Transformers Figure 5. 47 A three-phase wye-delta transformer with three-legged iron core. 9/15/2020 360 Chapter 5 Transformers 5

Transformers Usual connections for three-phase transformers 9/15/2020 360 Chapter 5 Transformers 6

5. 4. 1 Wye / Wye connection 9/15/2020 360 Chapter 5 Transformers 7

Transformers 5. 41. Wye/wye Figure 5. 48 Wye connected three-phase transformer 9/15/2020 360 Chapter 5 Transformers 8

Transformers Figure 5. 49 Three-phase network supplies a load through a transformer. Figure 5. 50 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. 9/15/2020 360 Chapter 5 Transformers 9

5. 4. 2 Wye / Delta connection 9/15/2020 360 Chapter 5 Transformers 10

Transformers Figure 5. 52 Wye-delta connected transformer , 5. 4. 2 9/15/2020 360 Chapter 5 Transformers 11

Transformers Figure 5. 52 Wye-delta connected transformer , currents and voltages 9/15/2020 360 Chapter 5 Transformers 12

Transformers Figure 5. 53 Single-phase equivalent circuit of a wye-delta transformer. 9/15/2020 360 Chapter 5 Transformers 13

5. 4. 3 Delta / Wye connection 9/15/2020 360 Chapter 5 Transformers 14

Transformers Figure 5. 54 Delta-Wye connected transformer 9/15/2020 360 Chapter 5 Transformers 15

5. 4. 4 Delta / Delta connection 9/15/2020 360 Chapter 5 Transformers 16

Transformers Figure 5. 55 Delta-Delta connected transformer 9/15/2020 360 Chapter 5 Transformers 17

Transformers Table 5. 1 Three-phase Transformer Relations Transformer Connect ion Primary and Secondary Voltage Phase Relation Phase S hi ft * 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 Zero AB and ab Windings Placed on the Same Leg * 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. 9/15/2020 360 Chapter 5 Transformers 18

5. 4. 7 Equivalent circuit parameters 9/15/2020 360 Chapter 5 Transformers 19

Transformers Figure 5. 56 Open circuit test for three-phase transformer parameter measurement 9/15/2020 360 Chapter 5 Transformers 20

Transformers Open circuit test 9/15/2020 360 Chapter 5 Transformers 21

Transformers Open circuit test 9/15/2020 360 Chapter 5 Transformers 22

Transformers Figure 5. 56 Short circuit test for three-phase transformer parameter measurement 9/15/2020 360 Chapter 5 Transformers 23

Transformers Short circuit test 9/15/2020 360 Chapter 5 Transformers 24

Transformers Short circuit test 9/15/2020 360 Chapter 5 Transformers 25

Exercises using MAT CAD 9/15/2020 360 Chapter 5 Transformers 26

Transformers Figure 5. 61 One-line diagram of delta-wye connected transformer supplies two balanced loads through a transmission line. 9/15/2020 360 Chapter 5 Transformers 27