Explanation: f= PN/120 Hz in India and many other countries, alternators feeding the power system generates at a frequency of 50 Hz. 9. How many poles should the alternators driven by the oil engines and hydraulic turbine prime movers must have, for better operation?
A. fewer number of poles
B. larger number of poles
C. medium number of poles
D. any of the mentioned
Answer:A
Explanation: f= PN/120 Hz in India and many other countries, alternators feeding the power system generates at a frequency of 50 Hz. 9. How many poles should the alternators driven by the oil engines and hydraulic turbine prime movers must have, for better operation?
A. fewer number of poles B. larger number of poles C. medium number of poles D. any of the mentioned
Explanation: Oil engines and hydraulic turbines operate best at relatively low speeds, therefore, the alternators driven by these prime movers must have relatively large number of poles, as f ∝ 1/N.