Question

Problem 3- At a location IMW of power at 50Hz is required, the only source available is at 60Hz. Pick a synchronous motor generator set to make this possible

Answer 1

Solution: Let Synchronous motor fed with 60 Hz source has poles Pm the speed of the motor is 120f 12060 Pm Pm 120 60 Frequency of generator should be 50 Hz.The speed generator which has poles 9 is 120 f 120 50 120 50 Since the speeds of both motor coupled with generator should be same 120 60 Pm 12050 120 60 12050

As the poles should be even multiply the ratio by 2, we get P 5 2 10 Pm 62 12 P 10 Pm 12 P10 poles P 12 poles The speed is . 120 60 120 60 -600 rpm 12 So the motor should be Nm- 600 rpm. Pm- 12 poles The generator should be Ng -600 rpm, Pg -10 poles