Transformers MCQs (Part-8)

What is the primary cause of magnetizing current in a transformer?

A Voltage imbalance
B High frequency
C Magnetic flux
D Load condition

What is inrush current in a transformer?

A High starting current
B Continuous current
C Low-frequency current
D Zero current

What is the purpose of transformer protection systems?

A Prevent overheating
B Increase efficiency
C Control voltage
D Detect faults

Which fault is most commonly detected by a differential protection relay in transformers?

A Inrush current
B Overload
C Short circuit
D Ground fault

What is the main function of a Buchholz relay in transformer protection?

A Control voltage
B Detect gas accumulation
C Measure temperature
D Detect oil level

What is the effect of inrush current on a transformer?

A Prevents fault detection
B Increases efficiency
C Causes transformer heating
D Reduces magnetizing current

How can inrush current be reduced in a transformer?

A Apply pre-magnetization
B Use smaller transformers
C Increase voltage
D Use resistors

What is the impact of magnetizing current on transformer operation?

A Decreases load capacity
B Increases efficiency
C Increases core losses
D Decreases power loss

Which protection device is used to prevent transformer from overloads?

A Differential relay
B Buchholz relay
C Oil pump
D Thermal relay

What is the role of the primary winding in the magnetizing current of a transformer?

A Control frequency
B Create magnetic field
C Generate voltage
D Generate heat

Why is a transformer’s magnetizing current typically small?

A High voltage
B High resistance
C Low flux density
D Low frequency

What is the function of an overcurrent relay in transformer protection?

A Detect overload conditions
B Prevent short circuits
C Control voltage
D Reduce inrush current

What happens when a transformer experiences a short circuit fault?

A Magnetizing current decreases
B Voltage increases
C Inrush current reduces
D Excessive current flows

What does the differential protection scheme of a transformer detect?

A Internal faults
B Temperature rise
C Voltage fluctuations
D Ground faults

How does an over-voltage relay protect transformers?

A Detects short circuits
B Disconnects the transformer under excessive voltage
C Prevents overheating
D Measures load current