Transformers MCQs (Part-3)

Which of the following is a primary function of a step-down transformer?

A To increase the voltage
B To decrease the voltage
C To reduce the current
D To regulate the frequency

What does a transformer’s impedance mainly consist of?

A Resistance and capacitance
B Resistance and reactance
C Resistance and voltage
D Voltage and current

Which type of transformer is used to maintain voltage stability and prevent power loss in long-distance transmission?

A Step-up transformer
B Step-down transformer
C Isolation transformer
D Autotransformer

What is the primary purpose of the cooling system in oil-filled transformers?

A To increase the insulation resistance
B To prevent the transformer from overheating
C To enhance the transformer’s magnetic field
D To regulate the voltage

Which of the following is the best insulating material for transformers?

A Wood
B Oil
C Air
D Water

What type of transformer is typically used to convert high-voltage AC to low-voltage AC for household appliances?

A Distribution transformer
B Isolation transformer
C Power transformer
D Autotransformer

Which test is used to evaluate the copper losses in a transformer?

A Open-circuit test
B Short-circuit test
C Load test
D Insulation test

What is the purpose of an earthing transformer?

A To increase the voltage
B To provide a neutral point in an electrical system
C To step down the voltage
D To protect the transformer from overcurrent

Which type of transformer is commonly used for protection against electrical shocks in critical systems?

A Step-up transformer
B Isolation transformer
C Power transformer
D Autotransformer

What is the typical frequency of operation for most transformers?

A 20 Hz
B 50 Hz or 60 Hz
C 100 Hz
D 200 Hz

What is the main advantage of using a dry-type transformer over an oil-filled transformer?

A Higher efficiency
B Reduced risk of fire
C Smaller size
D Easier installation

What is the main function of transformer protection devices?

A To reduce energy losses
B To protect against overloading, short circuits, and faults
C To regulate voltage
D To increase transformer efficiency

Which of the following losses occur in the core of a transformer?

A Copper loss
B Core loss (hysteresis and eddy current loss)
C Dielectric loss
D All of the above

What happens when the transformer experiences inrush current during startup?

A The voltage increases significantly
B The transformer experiences a brief surge of high current
C The transformer becomes inefficient
D The transformer becomes overloaded

What is the purpose of load testing a transformer?

A To determine the transformer’s core losses
B To determine the efficiency and temperature rise under load conditions
C To measure the insulation strength
D To measure the impedance of the transformer

What is the role of harmonics in transformer operation?

A Harmonics improve the transformer’s efficiency
B Harmonics increase transformer losses and cause overheating
C Harmonics reduce voltage regulation
D Harmonics have no effect on transformer performance

Which of the following transformers is commonly used in industrial applications to isolate different circuits?

A Power transformer
B Isolation transformer
C Step-up transformer
D Autotransformer

What does the “no-load loss” of a transformer refer to?

A Losses due to the resistance of the windings when no load is connected
B Losses caused by core magnetization and eddy currents when no load is connected
C Losses that occur only during load operation
D Losses due to the heating of the oil in oil-filled transformers

What is the role of insulation in transformers?

A To increase the efficiency of the transformer
B To provide safety by preventing electrical faults
C To store electrical energy
D To reduce the size of the transformer

What is a common fault in transformers?

A Overvoltage
B Overheating
C Low current
D Short circuit