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E283 Mid Term AY1213 S2 Part Sol

# E283 Mid Term AY1213 S2 Part Sol - Solution for Sem 2 Year...

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Solution for Sem 2 Year 2012/2013 Question 2 [30 marks] a) b) The efficiency of the power system improved by 7%. c) For an efficiency of 99%, the transmission line loss should be reduced to 816 W. Turns ratio of transformer 1 is 0.313 Turns ratio of transformer 2 is 3.19 d) In a real power system, the efficiency would be lower than that calculated in part (b) because a real transformer would have hysteresis loss, eddy current loss and copper loss. Details of the hysteresis, eddy current and copper losses.

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QUESTION 3 Answer: a) Interpoles: To rectify the problems of commutation due to pole shifting and L di/dt voltage effect. Resolve the arcing or sparking problem at the brushes and therefore, increase the brushes lifespan. Compensating windings: To rectify the problems of commutation due flux weakening. Can prevent the runaway condition where the speed of the motor will keep on increasing until the machine is disconnected from the power line or until it destroys itself.
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