Constructional Features of Rotating Electrical Machines – 3

For relatively large sizes of synchronous machines, which of the following are used for providing closed circuit cooling?

In larger DC machines, the reason behind using fabricated steel instead of cast iron in the manufacture of yoke is ?

In a synchronous generator, the frequency of the generated EMF depends on

How many poles should the alternators, driven by the steam and gas turbines prime movers must have, for better operation?

In a DC generator, the commutator serves as a _________

Commercially, which of the following generators is called turbo-alternators or turbo-generators?

In a DC motor, the commutator serves as a _____

In a DC machine, the pole core is usually of smaller cross section than the pole shoe because ___________
(i) smaller cross section requires less copper
(ii) larger pole shoe increases the air gap reluctance
(iii) larger pole shoe increases the flux per pole entering the armature
(iv) larger pole shoe reduces the mechanical strength
(v) larger pole shoe supports the field winding
Which of the above statements are correct?

A synchronous machine can be connected to an energy system only when ________

In a synchronous machine, cylindrical pole construction has been found to suit best for _________