Question

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

(a) fewer number of poles

(b) large number of poles

(c) medium number of poles

(d) any of the mentioned

The question was asked by my school teacher while I was bunking the class.

This question is from Constructional Features of Rotating Electrical Machines-3 topic in chapter Constructional Features of Rotating Electrical Machines of Electrical Machines

Answer 1

The correct option is (a) fewer number of poles

For explanation I would say: Steam and gas turbines have best operating characteristics at relatively high speeds, therefore, alternators driven by these must have a fewer number of poles, say 2 or 4, as f ∝ 1/N.