Q. In a step-up transformer, which of the following is true?
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A.
The primary voltage is higher than the secondary voltage
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B.
The primary current is higher than the secondary current
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C.
The turns ratio is greater than one
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D.
The power output is less than the power input
Solution
In a step-up transformer, the turns ratio is greater than one, which results in a higher secondary voltage compared to the primary voltage.
Correct Answer:
C
— The turns ratio is greater than one
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Q. In a transformer, what does the term 'turns ratio' refer to?
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A.
The ratio of primary to secondary voltage
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B.
The ratio of primary to secondary current
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C.
The ratio of primary to secondary turns
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D.
The ratio of power input to output
Solution
The turns ratio of a transformer is the ratio of the number of turns in the primary winding to the number of turns in the secondary winding.
Correct Answer:
C
— The ratio of primary to secondary turns
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Q. In load flow studies, what is the significance of transformer tap changing?
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A.
It affects the power factor
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B.
It adjusts the voltage levels
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C.
It increases the load capacity
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D.
It reduces losses
Solution
Transformer tap changing is significant in load flow studies as it adjusts the voltage levels to maintain system stability and efficiency.
Correct Answer:
B
— It adjusts the voltage levels
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Q. What is the main advantage of using a three-phase transformer over three single-phase transformers?
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A.
Lower cost
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B.
Higher efficiency
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C.
Reduced size and weight
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D.
All of the above
Solution
A three-phase transformer is generally more efficient, cost-effective, and compact compared to using three separate single-phase transformers.
Correct Answer:
D
— All of the above
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Q. What is the main disadvantage of using a dry-type transformer?
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A.
Higher cost
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B.
Lower efficiency
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C.
Larger size
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D.
Limited voltage ratings
Solution
Dry-type transformers tend to be more expensive compared to oil-filled transformers, which can be a disadvantage in certain applications.
Correct Answer:
A
— Higher cost
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Q. What is the primary application of a distribution transformer?
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A.
To step up voltage for transmission
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B.
To step down voltage for consumer use
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C.
To isolate circuits
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D.
To convert AC to DC
Solution
Distribution transformers are primarily used to step down voltage levels for consumer use in residential and commercial applications.
Correct Answer:
B
— To step down voltage for consumer use
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Q. What is the primary purpose of a transformer protection relay?
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A.
To increase transformer efficiency
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B.
To prevent transformer overheating
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C.
To detect faults and isolate the transformer
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D.
To improve voltage regulation
Solution
Transformer protection relays are designed to detect faults and isolate the transformer to prevent damage and ensure safety.
Correct Answer:
C
— To detect faults and isolate the transformer
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Q. What is the role of a transformer in renewable energy systems?
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A.
To convert DC to AC
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B.
To step up voltage for grid connection
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C.
To store energy
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D.
To regulate frequency
Solution
In renewable energy systems, transformers step up the voltage for grid connection, ensuring efficient transmission of generated power.
Correct Answer:
B
— To step up voltage for grid connection
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Q. Which of the following is a common application of a distribution transformer?
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A.
Power generation
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B.
Voltage stepping in transmission lines
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C.
Supplying power to residential areas
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D.
Industrial power supply
Solution
Distribution transformers are commonly used to supply power to residential areas by stepping down the voltage from the transmission lines.
Correct Answer:
C
— Supplying power to residential areas
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Q. Which type of transformer is commonly used for voltage regulation in distribution systems?
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A.
Isolation transformer
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B.
Auto transformer
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C.
Step-down transformer
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D.
Phase-shifting transformer
Solution
Auto transformers are often used for voltage regulation in distribution systems due to their ability to adjust voltage levels efficiently.
Correct Answer:
B
— Auto transformer
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Q. Which type of transformer is used to connect two systems operating at different frequencies?
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A.
Step-up transformer
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B.
Step-down transformer
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C.
Phase-shifting transformer
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D.
Frequency converter transformer
Solution
Phase-shifting transformers are used to connect systems operating at different frequencies, allowing for controlled power flow.
Correct Answer:
D
— Frequency converter transformer
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