Transformer Bank Workshop
Three Phase Connections

Audience:		Electrical distribution line personnel, engineers, and line supervisors
Average Training Time:		90 to 180 minutes NOTE
Format/ Product Code:		CD-ROM (MPEG Video)/ TBCONMPG
Content Producer:		Mastery Technologies, Inc.

OVERVIEW
This course is the second course in the “Transformer Bank Workshop” series. All the the courses in this series use full-screen, full-motion video.
This “near hands-on” course uses clear and concise presentations and eighty-seven interactions to convey the knowledge of three-phase transformer bank connections your workers need to build and service a bank.
3-D animations help clarify sometimes difficult concepts. Your workers will actually practice with and test on life-like computer-simulated transformer banks. They will make all transformer bank connections with the mouse or touchscreen.
In this course your line personnel will learn how to make basic transformer bank connections. They’ll also learn when and why they’re used.
The course teaches how transformation is accomplished. Workers will learn to identify the various types of transformers and their main parts. They will also learn how series and parallel connections are used in transformations. Through computer simulation activities, workers will actually make delta and wye connections for the both primary and the secondary.
This course was produced in collaboration with Otter Tail Power Company and Gordon Solee, PE. The program is based on Mr. Solee’s popular and respected “Transformer Hands-On Workshop”.

TOPICS
The course presents interactive instruction covering the following topical areas:

The Transformer

• Nomenclature and Purpose
• Transformation
• Bushing Identification
• Polarity
• Transformer Current Capacity

Series and Parallel

• Secondary Windings
• Single-Phase Paralleling

Delta Connections

• Primary Delta
• Secondary Delta
• Sequence
• Secondary Voltages
• Mixed Polarity
• Open Bank
• Grounding The Secondary

Wye Connections

• Primary Wye
• Grounding
• Secondary Wye
• Sizing The Risers

PERFORMANCE OBJECTIVES
This course will measure mastery on each of the following performance objectives. Upon completion, workers will be able to...

Explain the turns ratio/voltage ratio

1. Determine the turns ratio from a nameplate voltage rating.
2. Correlate the number of turns on the primary and secondary coils to the related voltages.
3. Calculate the voltage ratio for a given winding.
4. Explain how the turns ratio of the transformer applies to current output.
5. Explain how the turns ratio of the transformer applies to voltage output.

Determine the polarity of a transformer

1. Connect the transformer for a polarity test.
2. Measure the voltages required for a polarity test.
3. Interpret the results of a set of voltage measurements to conclude the polarity.

State standards for polarity and bushing ID

1. Identify a subtractive polarity transformer based on its nameplate kVA rating.
2. Identify an additive polarity transformer based on its nameplate kVA rating.
3. Identify the polarity of a transformer based on the secondary bushing IDs.
4. Identify the H1 bushing.

Determine if a single-phase transformer is overloaded

1. Calculate current capacity for a single-phase transformer of a specific kVA rating.
2. Calculate the kVA load on a single-phase transformer.
3. Measure the actual load current on a single-phase transformer.

Connect secondary windings in series and parallel

1. Connect the transformer secondary coils in parallel for a four-bushing transformer.
2. Connect the multiple secondary windings in series for a four-bushing transformer.

Connect the primary in a delta

1. Identify the delta bus.
2. Connect a closed delta on the primary.
3. Roll the primary 120 degrees on a closed delta bank.
4. Connect an open delta on the primary.
5. Roll the primary 120 degrees on an open delta bank.

Connect the secondary in a delta

1. Connect the secondary 120/240 volt, three-phase, four-wire.
2. Connect the secondary 240 volt, three-phase, three-wire.
3. Connect the secondary 240 volt, three-phase, corner ground.
4. Connect the secondary 240/480 volt, three-phase, four-wire.
5. Connect the secondary 480 volt, three-phase, three-wire.
6. Connect the secondary 480 volt, three-phase, three-wire, corne ground.
7. Identify the power phase on a 120/240 volt, three-phase, four-wire bank.

Predict secondary voltages

1. Predict the voltage of a secondary line to ground connection.
2. Predict the voltage of a secondary line to line connection.

Connect the primary in a wye

1. Connect the primary wye ungrounded, source to H1.
2. Connect the primary wye ungrounded, source to H2.
3. Connect the primary wye grounded, source to H1.
4. Connect the primary wye grounded, source to H2.
5. Connect the primary open wye.

Connect the secondary in a wye

1. Connect a three-bushing secondary to provide 120/208Y volts, three-phase, four-wire.
2. Connect a two-bushing secondary to provide 277/480Y volts, three-phase, four-wire.

Predict secondary voltages

1. Predict the voltage of a secondary line to ground connection.
2. Predict the voltage of a secondary line to line connection.

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