Question 1

The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
A)Conduction
B)Convection
C)Radiation
D)All ofthe above

Accepted Answer

Electrical machines dissipate heat through conduction, convection, and radiation, as all these modes contribute to heat transfer from the machine to its surroundings.

Question 2

The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc.
A)conduction
B)convection
C)radiation
D)any ofthe above

Accepted Answer

Radiation is the mode of heat transfer that depends on the temperature of the body and its surface characteristics, such as color and roughness, without requiring any medium for the transfer.

Question 3

The mcrease in heat dissipation by air blasts is due to increase in
A)conduction
B)convection
C)radiation
D)any ofthe above

Accepted Answer

The increase in heat dissipation by air blasts is primarily due to an increase in convection, as moving air enhances the heat transfer from a surface by replacing the warmed air with cooler air more efficiently.

Question 4

On which of the following variables heat convected depends ?
A)Power density
B)Temperature difference between heated surface and coolant
C)Thermal resistivity, density, specific heat
D)All ofthe above

Accepted Answer

Heat convection depends on various factors including power density, which affects the rate of heat generation; temperature difference between the heated surface and the coolant, which drives the heat transfer; and properties of the medium such as thermal resistivity, density, and specific heat, which influence how heat is absorbed and transferred through the medium.

Question 5

Which ofthe following methods is used for air cooling of turbo-alternators ?
A)One sided axial ventilation
B)Two sided axial ventilation
C)Multiple inlet system
D)All ofthe above

Accepted Answer

All the mentioned methods (one sided axial ventilation, two sided axial ventilation, and multiple inlet system) are used for air cooling of turbo-alternators.

Quiz 1: Design Considerations and Materials for Electrical Machines

The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?

The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc.

The mcrease in heat dissipation by air blasts is due to increase in

On which of the following variables heat convected depends ?

Which ofthe following methods is used for air cooling of turbo-alternators ?