Interesting thing about the squirrel cage type and wound type rotor

In both type of rotors the rotor slots will not be in  parallel with rotor shaft axis, this is done to get smoother operation.

DC generators

When are separately excited DC generators used?
Ans: If we want wide range of output voltage then SEPARATELY EXCITED DC GENERATORS are used.

But if want to maintain constant terminal voltage then we have to use CUMULATIVELY COMPOUNDED SELF EXCITED GENERATORS.