Suburban transportation is usually powered at 25Hz Using a s

Suburban transportation is usually powered at 25Hz. Using a synchronous motor as the prime mover to drive a generator, 50Hz power needs to be generated. Find the number of poles in each machine.

Solution

speed of synchronous motor = (120*frequency of operation)/poles

speed of synchronous motor =50

frequency of operation =25

therefore, poles = 120*25/50 = 60