11. In an induction motor, if the air gap is increased
- its speed will reduce
- its efficiency will improve
- its power factor will reduce
- its breakdown torque will reduce
12. The squirrel cage rotor of a 6-pole induction motor can be used for _____ induction motor.
- only 6-pole
- 6 or 12 pole
- any number of poles in an
- none of the above
13. In a 3-phase slip ring induction motor, the rotor winding terminals are brought out through slip rings to
- connect extra resistance across them during starting
- connect them either in star or in delta as per need
- connect to 3-phase ac supply
- close the rotor circuit externally
14. The squirrel cage induction motors are provided with blades in order to
- facilitate cooling of rotor
- balance the rotor dynamically
- eliminate noise
- none of these
15. The rotor winding for a 3-phase slip ring induction motor having delta connected stator must be connected in
- delta
- star
- delta or star according to need
- none of the above
16. The frame of an induction motor is made of
- aluminium
- silicon steel
- closed grained cast iron
- stainless steel
17. In a 3-phase slip ring induction motor, brushes are connected to
- external star connected resistors
- dc supply
- 3-phase ac supply
- equalizing coils
18. A smaller air gap in a polyphase induction motor helps to
- reduce the chance of crawling
- increase the starting torque
- reduce the chance of cogging
- reduce the magnetizing current
19. In an induction motor, the air gap flux density is usually kept low so as to
- improve efficiency
- improve power factor
- reduce machine cost
- none of the above
20. A wound rotor induction motor can be distinguished from squirrel cage induction motor by
- presence of slip rings
- size of frame
- shaft diameter
- any of the above