11.) A motor with apparent power 1 MVA, main voltage 6.6 kV, f = 50 Hz. The spee

Question

11.) A motor with apparent power 1 MVA, main voltage 6.6 kV, f = 50 Hz. The speed is 3000 rpm. What is the pole number (pure number value)?

12.) A 3-phase synchronous generator with pole number 8 has apparent power 2 MVA and power factor is 0.8. Dismisses any losses. What is the moment? Enter the answer as the number value (number of NM, enter no device), round to the nearest integer.

13.) An industry charges the power grid by 7 MW, cos fi = 0.72 (in). They want to change this with a synchronous motor to 8 MW, cos fi = 0.85 (in). What is the change in reactive power (enter the amount in MVAr by one decimal place, do not write the device)?

Explanation / Answer

Problem 11).

Given that

Frequency = 50 Hz and

Speed = 3000 rpm

So, relation between speed , Frequency and poles is given by. P = ( 120 * F ) / N

Where ,. N = speed in rpm

P = ( 120 * 50 ) / 3000

P = 2.

Therefore number of poles of a given motor is 2 poles.

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