Electrical Machines (Part-7)

What is the primary cause of copper losses in electrical machines?

A Friction
B Hysteresis
C Resistance of windings
D Eddy currents

What is the role of insulation in electrical machines?

A Increase efficiency
B Prevent electrical faults
C Prevent overheating
D Improve cooling

What type of loss is minimized by using laminated cores in electrical machines?

A Eddy current loss
B Hysteresis loss
C Copper loss
D Mechanical loss

How does the efficiency of an electrical machine relate to losses?

A Efficiency is unaffected by losses
B Efficiency increases with losses
C Efficiency depends on torque
D Efficiency decreases with losses

What is the primary function of the cooling system in electrical machines?

A To enhance torque
B To reduce vibration
C To prevent overheating
D To increase speed

What happens when the core of an electrical machine overheats?

A Insulation breaks down
B Torque increases
C Efficiency improves
D Speed increases

What is the main cause of mechanical losses in electrical machines?

A Copper resistance
B Friction in bearings
C Eddy currents
D Hysteresis

How does the temperature affect the performance of an electrical machine?

A Torque increases with higher temperature
B Performance remains constant
C Efficiency decreases with higher temperature
D Performance improves with higher temperature

What is the effect of higher ambient temperature on an electrical machine?

A Increases speed
B Improves insulation
C Increases torque
D Increases losses

What is the function of a heat sink in an electrical machine?

A To reduce noise
B To increase efficiency
C To improve cooling
D To increase speed

What happens to the insulation resistance of a motor as it ages?

A Remains constant
B Decreases
C Becomes more efficient
D Increases

Which type of loss is a result of the mechanical movement of the rotor?

A Hysteresis loss
B Eddy current loss
C Friction loss
D Copper loss

What effect does increasing the supply voltage have on the efficiency of an electrical machine?

A Increases torque
B No effect
C Increases efficiency
D Decreases efficiency

Which of the following is NOT a method of cooling for electrical machines?

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

What is the primary source of energy losses in electrical machines operating under normal conditions?

A Copper losses
B Friction losses
C Electrical losses
D Core losses