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Questions and Answers
Where is Dr. Philip Yaw Okyere currently teaching?
Where is Dr. Philip Yaw Okyere currently teaching?
- Kwame Nkrumah University of Science and Technology, Kumasi (correct)
- University of Cape Coast, Cape Coast
- L’Institut National Polytechnique de Grenoble (INPG), France
- University of Ghana, Accra
What is the title of the course Dr. Philip Yaw Okyere is teaching?
What is the title of the course Dr. Philip Yaw Okyere is teaching?
- Electrical Machines
- Power Electronics
- Electromechanical Energy Conversion and Transformers (correct)
- Power Systems
Where did Dr. Philip Yaw Okyere pursue his postgraduate studies?
Where did Dr. Philip Yaw Okyere pursue his postgraduate studies?
- Kwame Nkrumah University of Science and Technology, Kumasi
- University of Cape Coast, Cape Coast
- L’Institut National Polytechnique de Grenoble (INPG), France (correct)
- University of Ghana, Accra
What is Dr. Philip Yaw Okyere's current position?
What is Dr. Philip Yaw Okyere's current position?
What is the degree Dr. Philip Yaw Okyere graduated with in 1979?
What is the degree Dr. Philip Yaw Okyere graduated with in 1979?
Where can Dr. Philip Yaw Okyere be contacted?
Where can Dr. Philip Yaw Okyere be contacted?
What is the credit value of the course EE 162?
What is the credit value of the course EE 162?
What is Dr. Philip Yaw Okyere's field of specialization?
What is Dr. Philip Yaw Okyere's field of specialization?
What is the equivalent of the secondary terminal voltage on no load?
What is the equivalent of the secondary terminal voltage on no load?
What is the relationship between the current in the primary and the current in the secondary?
What is the relationship between the current in the primary and the current in the secondary?
What is the voltage to be applied to the primary to obtain the rated current in the secondary when the secondary terminal voltage is 240 V?
What is the voltage to be applied to the primary to obtain the rated current in the secondary when the secondary terminal voltage is 240 V?
What is the load power factor angle?
What is the load power factor angle?
What is the voltage across the equivalent leakage impedance?
What is the voltage across the equivalent leakage impedance?
What is the input power factor?
What is the input power factor?
What is the primary current when the secondary terminal voltage is 240 V?
What is the primary current when the secondary terminal voltage is 240 V?
What is the phase angle between the primary voltage and current?
What is the phase angle between the primary voltage and current?
What is the relationship between V1,2 and V1,1 when the number of turns and cross section remain the same?
What is the relationship between V1,2 and V1,1 when the number of turns and cross section remain the same?
What is the unit of hysteresis loss WH?
What is the unit of hysteresis loss WH?
How does the hysteresis loss change with frequency?
How does the hysteresis loss change with frequency?
What is the relationship between the eddy-current loss and frequency?
What is the relationship between the eddy-current loss and frequency?
What is the purpose of the phasor diagram on no load?
What is the purpose of the phasor diagram on no load?
What is the total iron loss in the transformer core at 60 Hz?
What is the total iron loss in the transformer core at 60 Hz?
What is the hysteresis loss at 25 Hz in Example 6?
What is the hysteresis loss at 25 Hz in Example 6?
What is the eddy-current loss at 50 Hz in Example 6?
What is the eddy-current loss at 50 Hz in Example 6?
What is the primary application of a delta-star connection?
What is the primary application of a delta-star connection?
What is the main use of a star-delta connection?
What is the main use of a star-delta connection?
What is the problem that can occur in a star-star connection if the secondary load is unbalanced?
What is the problem that can occur in a star-star connection if the secondary load is unbalanced?
What is the purpose of connecting the neutral of the primary and the neutral of the source together in a star-star connection?
What is the purpose of connecting the neutral of the primary and the neutral of the source together in a star-star connection?
Which of the following connections is economical for high-voltage transformers?
Which of the following connections is economical for high-voltage transformers?
What is the characteristic of a delta-star connection that allows it to provide a four-wire supply?
What is the characteristic of a delta-star connection that allows it to provide a four-wire supply?
What is the type of connection that has no secondary neutral and cannot provide a four-wire supply?
What is the type of connection that has no secondary neutral and cannot provide a four-wire supply?
What is the common application of a delta-star connection in distribution service?
What is the common application of a delta-star connection in distribution service?
What is the primary reason for using high-grade grain-oriented steel in transformer core?
What is the primary reason for using high-grade grain-oriented steel in transformer core?
What is the main purpose of laminating the transformer core?
What is the main purpose of laminating the transformer core?
What is the advantage of core-type construction in transformer?
What is the advantage of core-type construction in transformer?
Why are the transformer windings carefully insulated from each other and from the core?
Why are the transformer windings carefully insulated from each other and from the core?
What is the purpose of adding 3 to 4% silicon to the transformer core?
What is the purpose of adding 3 to 4% silicon to the transformer core?
What type of transformer construction has the primary and secondary windings distributed over both core legs?
What type of transformer construction has the primary and secondary windings distributed over both core legs?
What is the purpose of polarity tests on a transformer?
What is the purpose of polarity tests on a transformer?
What is the main advantage of using iron as the core material in transformer?
What is the main advantage of using iron as the core material in transformer?
Flashcards
Dr. Philip Yaw Okyere's current teaching location
Dr. Philip Yaw Okyere's current teaching location
Kwame Nkrumah University of Science and Technology, Kumasi
Course taught by Dr. Okyere
Course taught by Dr. Okyere
Electromechanical Energy Conversion and Transformers
Dr. Okyere's postgraduate study location
Dr. Okyere's postgraduate study location
L’Institut National Polytechnique de Grenoble (INPG) in France
Dr. Okyere's academic title
Dr. Okyere's academic title
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Dr. Okyere's undergraduate degree in 1979
Dr. Okyere's undergraduate degree in 1979
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Dr. Okyere's field of specialization
Dr. Okyere's field of specialization
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Credit value of course EE 162
Credit value of course EE 162
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Equivalent of secondary terminal voltage on no load
Equivalent of secondary terminal voltage on no load
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Primary and secondary current relationship
Primary and secondary current relationship
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Voltage applied to primary for rated secondary current
Voltage applied to primary for rated secondary current
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Load power factor angle
Load power factor angle
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Voltage across equivalent leakage impedance
Voltage across equivalent leakage impedance
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Input power factor
Input power factor
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Primary current at secondary voltage of 240 V
Primary current at secondary voltage of 240 V
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Phase angle between primary voltage and current
Phase angle between primary voltage and current
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Relationship between V1,2 and V1,1
Relationship between V1,2 and V1,1
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Unit of hysteresis loss (WH)
Unit of hysteresis loss (WH)
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Hysteresis loss change with frequency
Hysteresis loss change with frequency
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Eddy-current loss relationship with frequency
Eddy-current loss relationship with frequency
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Purpose of phasor diagram on no load
Purpose of phasor diagram on no load
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Total iron loss in transformer core at 60 Hz
Total iron loss in transformer core at 60 Hz
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Hysteresis loss at 25 Hz in Example 6
Hysteresis loss at 25 Hz in Example 6
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Eddy-current loss at 50 Hz in Example 6
Eddy-current loss at 50 Hz in Example 6
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Primary application of delta-star connection
Primary application of delta-star connection
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Main use of star-delta connection
Main use of star-delta connection
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Star-star connection problem with unbalanced load
Star-star connection problem with unbalanced load
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Purpose of connecting neutrons in star-star connection
Purpose of connecting neutrons in star-star connection
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Economical connection for high-voltage transformers
Economical connection for high-voltage transformers
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Characteristic of delta-star for four-wire supply
Characteristic of delta-star for four-wire supply
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Connection with no secondary neutral
Connection with no secondary neutral
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Common application of delta-star in distribution service
Common application of delta-star in distribution service
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Reason for using high-grade grain-oriented steel
Reason for using high-grade grain-oriented steel
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Main purpose of laminating the transformer core
Main purpose of laminating the transformer core
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Advantage of core-type construction in transformer
Advantage of core-type construction in transformer
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Reason for insulation in transformer windings
Reason for insulation in transformer windings
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Purpose of adding silicon to transformer core
Purpose of adding silicon to transformer core
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Type of construction with distributed windings
Type of construction with distributed windings
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Purpose of polarity tests on a transformer
Purpose of polarity tests on a transformer
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Main advantage of iron as core material
Main advantage of iron as core material
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Study Notes
Transformer Parameters and Calculations
- A transformer is rated 10 kVA, 2400/240 V, 60 Hz, with parameters Rm = 80 kΩ, Xm = 35 kΩ, Re1 = 8.4 Ω, and Xe1 = 13.7 Ω for the approximate equivalent circuit.
- To obtain the rated current in the secondary, a voltage needs to be applied to the primary, which can be calculated using the given parameters.
Phasor Diagrams and Power Factor
- The input power factor can be calculated using the phase angle between V1 and I1.
- The load power factor angle can be calculated using the cosine inverse of the load power factor.
Transformer Construction and Design
- Power transformers are designed to approach the characteristics of an ideal transformer.
- The core is made of iron and forms a closed magnetic circuit to attain high permeability and a small magnetizing current.
- High-grade grain-oriented steel with a narrow hysteresis loop is used to reduce hysteresis loss.
- The core is laminated with 3-4% silicon added to increase the resistivity of the steel and reduce eddy current loss.
Magnetic Circuits and Windings
- Two main forms of magnetic circuits are used: core-type and shell-type arrangements.
- The primary and secondary windings are distributed over both core legs to reduce the amount of copper and minimize copper losses.
- The transformer windings are carefully insulated from each other and from the core.
Polarity Tests and Connections
- The four terminals of a single-phase transformer can have either additive or subtractive polarity.
- Common connections include delta-delta, delta-star, star-delta, and star-star connections, each with its own application and characteristics.
Iron Losses and Eddy Currents
- Hysteresis loss and eddy current loss can be calculated using the area of the hysteresis loop and the frequency of operation.
- The total iron loss in a transformer core can be calculated by summing the hysteresis loss and eddy current loss.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Calculate the voltage and current in a transformer's equivalent circuit using given parameters. This quiz is for electrical engineering students.
