Selection of number of poles in dc machines

How is the number of poles selected in a DC machine?

• a) Based on the speed requirement

• b) Based on the torque requirement

• c) Based on the power requirement

• d) Based on the voltage requirement

What is the typical range of poles in DC machines?

• a) 2-4

• b) 4-8

• c) 8-12

• d) 12-20

What is the advantage of using a DC machine with more poles?

• a) Higher efficiency

• b) Higher power output

• c) Smaller size

• d) Lower cost

What is the disadvantage of using a DC machine with more poles?

• a) Higher cost

• b) Lower efficiency

• c) Lower power output

• d) Larger size

How does increasing the number of poles affect the speed of a DC machine?

• a) Speed decreases

• b) Speed increases

• c) Speed remains the same

• d) Speed cannot be determined

In a DC machine, if the number of poles is doubled, what happens to the armature current?

• a) Doubles

• b) Halves

• c) Remains the same

• d) Cannot be determined

What is the effect of increasing the number of poles on the commutation process in a DC machine?

• a) Improved commutation

• b) Worsened commutation

• c) No effect on commutation

• d) Cannot be determined

Which type of DC machine is typically used for high-speed applications?

• a) Shunt DC machine

• b) Series DC machine

• c) Compound DC machine

• d) Permanent magnet DC machine

What is the typical range of poles in a permanent magnet DC machine?

• a) 2-4

• b) 4-8

• c) 8-12

• d) 12-20

In a DC machine, if the number of poles is decreased, what happens to the armature reaction?

• a) Increases

• b) Decreases

• c) Remains the same

• d) Cannot be determined