Between d.c generators and a.c generators

[neduet]

Hi friends

Between d.c generators and a.c generators only difference is commutator which rectified a.c to d.c. or any thing other.
What need of d.c generator? Because I never see anywhere d.c generator

thanks a lot

 

[harroxelas]

Well, for one, the field on a dc generator is usually on the stator, while in a ac generator, the field usually in the rotor. Also, the voltage generated "behind" the commutator is not sinusoidal, unlike on the voltage generated on a ac machine.

 

[neduet]

work of commutator and brushes rectified or conducting only so it is not in a.c generated right?
voltage generated "behind" the commutator is not sinusoidal ?

 

[donbcg]

DC generators require full retrace. The positive must flow all the way to the work and back to the generator or battery to cpmplete the circuit causing heat and severe loss. DC requires large conductors and can only be kept at short disyances.

AC is sinusodal, or alternates between high and low. Allowing unlimited transfer length because the electrons never have to return to the source.

By the two methods, ac provides cost efficiency for transfer, dc for cost efficiency in actual production.

AC is just cheaper to move. Furthermore, AC can never be stored. Whereas, DC can be stored.