46

Describe the
advantages of laminated structure of DC machine.

Advantages of laminated structure


47

Describe the
importance of time constant in the DC machine.

Lower the time constant of the
machine, faster its dynamic response


48

Describe the
effect of lamination on the time constant of DC machine.

The time constant of DC machine
reduces as the thickness of lamination decreases and vice versa.


49

Which are the
main factors affecting reactance voltage in the DC machine?

Factor affecting reactance voltage


50

How the
numbers of armature turns affect the reactance voltage?

Armature turns – Reactance voltage


51

Why the SCR
fed DC motor has more armature coil than the pure DC?

The SCR fed DC motor is de – rated due
to higher copper losses, higher iron losses and heating condition therefore
SCR fed DC motor has more armature coil than when it is fed through pure DC.


52

How the large
diameter of commutator affects the stability of the DC machine?

Diameter of commutator


53

Which are the
factors to be considered before selecting average flux density in the DC
machine?

Average flux density in air gap


54

Why the flux
density at the root of teeth is limited up to 2.2 weber / meter^{2}?

Flux density in the teeth


55

Describe the
effect of average flux density on the size of DC machine.

Relation between size of machine and
average flux density


56

Why the semi
closed machine has high value of ampere conductors per meter than that of closed
machines?

Ampere conductor per meter


57

Give reason :
The higher value of ampere conductors should used for high speed machines.

Relation between ampere conductors and
speed


58

Give reason :
The low value of ampere conductors should be used for high voltage machines.

Relation between ampere conductor and
voltage rating of machines


59

Which are the
factors to be considered while selecting ampere conductor per meter of the DC
machine?

Ampere conductor per meter


60

Describe the effect
of ampere conductors on the size of the DC machine.

Ampere conductors – Size of machine

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