Question

THESE ARE QUESTION FROM THE TOPIC POWER FACTOR IMPROVEMENT FROM THE SUBJECT POWER SYSTEM FUNDAMENTALS PLEASE DO THE QUESTIONS STEP BY STEP AND IN NEAT HAND WRITTING THE ANSWERS ARE GIVEN WITH THE QUESTIONS

1) . A station supplies 250 kVA at a lagging power factor of 0·8. A synchronous motor is connected in parallel with the load. If the combined load is 250 kW with a lagging p.f. of 0.9, determine :

(i) the leading kVAR taken by the motor.

(ii) kVA rating of the motor.

(iii) p.f. at which the motor operates.    ANS [(i) 28·9 kVAR (ii) 57·75 kVA (iii) 0·866 lead]

2) A generating station supplies power to the following :

(i) a lighting load of 100 kW;

(ii) an induction motor 800 h.p. (596·8 kW) p.f. 0·8 lagging, efficiency 92%;

(iii) a rotary converter giving 150 A at 400 V at an efficiency of 0·95.

What must be the power factor of the rotary convertor in order that power factor of the supply station may become unity ?    ANS [0·128 leading]  

Answer 1