Induction and Synchronous Machines MCQs (Part-12)

What is the primary function of cooling methods in induction motors?

A Increase power
B Improve efficiency
C Control temperature
D Reduce noise

Which of the following insulation materials is commonly used in electric motors?

A Paper
B Copper
C Varnish
D Rubber

What is the role of field windings in a synchronous motor?

A Reduce slip
B Control speed
C Generate torque
D Create magnetic field

What type of cooling method is most commonly used in large induction motors?

A Oil cooling
B Liquid cooling
C Water cooling
D Air cooling

What happens to the insulation material in motors when exposed to excessive heat?

A It hardens and cracks
B It becomes more conductive
C It lowers temperature
D It increases efficiency

What is the primary function of a ventilation system in an electric motor?

A Supply air to the rotor
B Prevent rust
C Increase the motor speed
D Cool the motor components

Which of the following is a common method of cooling used in synchronous generators?

A Water cooling
B Hydrogen cooling
C Air cooling
D Oil cooling

What is a disadvantage of using air cooling in induction motors?

A Low efficiency
B Ineffective for large motors
C Increases size
D High maintenance cost

Which cooling method is used in high-efficiency induction motors?

A Forced air cooling
B Oil immersion cooling
C Natural convection
D Water cooling

What is the impact of poor insulation on an electric motor?

A Increases speed
B Improves efficiency
C Increase torque
D Increases heating and reduce lifespan

What is the role of cooling fans in synchronous machines?

A Maintain rotor speed
B Dissipate heat from the motor
C Regulate voltage
D Increase excitation

How do liquid-cooled induction motors differ from air-cooled motors?

A Air-cooled motors are less expensive
B Liquid-cooled motors need more maintenance
C Liquid-cooled motors are more efficient
D Liquid-cooled motors are larger

What is a key feature of an epoxy resin used for motor insulation?

A High voltage resistance
B High thermal conductivity
C High flexibility
D Low cost

How does the cooling of an electric motor affect its performance?

A Cooling reduces current draw
B Cooling increases torque
C Cooling improves efficiency by preventing overheating
D Cooling reduces friction losses

What is the effect of improper ventilation in synchronous motors?

A Faster startup
B Reduced efficiency and overheating
C Higher torque
D Improved voltage regulation