Quiz No:46 Alternator RRB , Coal India , PWD , Engineering diploma Level , PSC

1. Which of the following features of induc­tion motor helps in preventing cogging of motor?


2. If the slip of the rotor of an induction motor is halved, the value of rotor reactance—


3. In terms of slip S, the ratio (Rotor output/ Rotor input)=?


4. What is the ratio of rotor copper loss to rotor output if the slip is 8%?


5. 3 phase induction motors usually operate on—


6. In ‘Cogging’ the motor—


7. In a double cage induction motor the under cage has—


8. If a squirrel cage induction motor runs hot the possible cause could be—


9. If a squirrel cage induction motor runs slow, the probable cause could be—


10. Full load current of a 1 HP single phase motor will be about—


11. The maximum size of fuse for protecting 5 HP, 3 phase, 440 V motor for direct start, should be—


12. The induction motor will run at synchronous speed if it is run—


13. The number of slip rings on a squirrel cage induction motor is —


14. In case of a three phase induction motor, the resultant flux—


15. When the supply to an induction motor is switched on, in the beginning the induced emf in the rotor will be—


16. In induction motors, the rotor slots are skewed to reduce—


17. For an induction motor the ratio of direct on line starting current to full load current is in the range —


18. Induction motors .provided with open slots have—


19. Which of the following is not the usual rated voltage for 3 phase induction motors?


20. Induction motors of 500 kW are usually ran on—


21. The range of slip for induction motor is normally—


22. The speed of a 60 Hz, 14 pole motor with slip of 0.05 will be—


23. The frequency of the induced emf in the rotor circuit is maximum—


24. A three phase induction motor connected to 2 phase supply—


25. The maximum torque in an induction motor neglecting stator impedance occurs at—