Quiz No:45 Alternator RRB , Coal India , PWD , PSC , Engineering diploma Level

1. Abrasive dust and dirt is best removed from an induction motor by—


2. When the rotor of an induction motor is standstill the value of the slip is—


3. Motors for fans and pumps are selected in the rpm range—


4. The class of insulation generally riot provided on electric motor is —


5. An induction motor is said to be crawling when—


6. Direct on line starting current as compared with star delta starting current is approximately—


7. The efficiency of induction motor is expected to be in the range—


8. Which of the following motors will be cheapest?


9. Full load current of a 20HP, 3 phase, 50 Hz, 440 V in induction motor is—


10. The number of poles in a phase induction motor at 50 cycles per second running below 1500 rpm will be—


11. For a 5 HP 3 phase induction motor the full load current on 440 V supply will be—


12. Which of the following will improve in case air gap length of a three phase induction motor is reduced?


13. Which of the following is likely to be the full load power factor of a three phase induction motor?


14. No load power factor of a three phase induction motor is expected to be closer to—


15. Full load current of an induction motor is 20A. The no load current may be expected to be-


16. in terms pf slip S, the ratio (Rotor copper loss/ Rotor output)=?


17. Which of the following methods can be used for the speed control of an induction motor?


18. Jagging of an induction motor is—


19. Which motor has the highest power to weight ratio?


20. In terms of slip S, the ratio Rotor copper loss/Rotor input=?


21. Which motor will have smallest shaft diameter?


22. An induction motor operates at maximum power factor when operating on—


23. Which of the following motor is expected to have the least value of slip?


24. A, 4 pole, 3 phase, 50 Hz induction motor running at 1450 rpm will have percentage slip of—