powerpoint ® presentation chapter 4 transformer connections voltage transformation three-phase...

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PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye Connections Wye-to-Wye Connections Wye-to-Delta Connections Delta-to-Delta Connections Open Delta Connections Delta Connection with High Leg to Ground Three-Phase Transformer Polarity

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Page 1: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

PowerPoint® Presentation

Chapter 4Transformer Connections

Voltage Transformation Three-Phase Circuits

Delta Connections Wye Connections

Delta-to-Wye Connections Wye-to-Wye

Connections Wye-to-Delta Connections

Delta-to-Delta Connections Open Delta

Connections Delta Connection with High Leg to Ground Three-Phase Transformer Polarity

Page 2: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

The low‑voltage winding of a standard distribution transformer connected to a single-phase circuit is normally made with two equal coils. These sections are arranged so that they may be connected in series or parallel.

Page 3: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Transformer polarity may be subtractive or additive.

Page 4: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

The polarity of a transformer may be determined using a known transformer or with AC voltage.

Page 5: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

A delta connection has the wires from the ends of each coil connected end-to-end to form a closed loop.

Page 6: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Studying the current in a delta-connected system at both 0° and 90° illustrates the current flow in a delta-connected system.

Page 7: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

A wye connection has one end of each coil connected together and the other end of each coil left open for external connections.

Page 8: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Studying the current in a wye-connected system at both 0° and 90° illustrates the current flow in a wye-connected system.

Page 9: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

A 3-phase delta-to-wye connection is often used for distribution where a four-wire secondary distribution circuit is required.

Page 10: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Three single-phase transformers may be connected in a wye-to-wye connection to form a 3-phase transformer.

Page 11: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

A wye-to-delta connection permits single-phase and 3-phase loads to be drawn simultaneously from the delta-connected secondary at the same voltage.

Page 12: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

In a wye-to-delta connection of three single-phase transformers, one unit may be disconnected from the circuit and service maintained with the secondary operating in open delta connection at 57.7% of normal bank capacity.

Page 13: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

In a delta-to-delta connection, the voltage of each transformer is equal to the 3-phase line voltage and the current in each of the transformers is only 57.7% of the line current.

Page 14: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Grounding one of the midpoints of the windings provides 240 V/120 V, single-phase, 3-wire service for lighting applications.

Page 15: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

An open delta connection makes 3-phase power available anywhere along the distribution line with the use of only two transformers rather than the usual three.

Page 16: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

A delta connection with a high leg to ground provides 240 V, 3-phase power to equipment and 120 V power for lighting and receptacles.

Page 17: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

The phase sequence on the secondary of a three-phase transformer is the same as the phase sequence on the primary.

Page 18: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Transformers are classified into connection groups according to their phase shift.

Page 19: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections

Page 20: PowerPoint ® Presentation Chapter 4 Transformer Connections Voltage Transformation Three-Phase Circuits Delta Connections Wye Connections Delta-to-Wye

Chapter 4Transformer Connections