electric drive( makut exam important questions) mcq -3

Makaut exam odd semester for 4th year Electrical engineering very important questions answers 

1. THE heating time constanat of an electrical machines gives an induction of its 
Ans- cooling

2. Intermitted duty rating of an electric motor 
Ans- is equal to name plate rating

3. To get the speed higher than the base speed of a dc shunt motar 
Ans- field control is used

4. Starting current of a motar is kept low 
Ans- to avoid excessive heating

5. If slip value is less than 1, it means the machine is 
Ans- Generating

6. The method of interchanging the input supply terminals of the motor is called 
Ans-  plugging

7. Calculate the flux produced by the Dc series field winding using the following data , Ia = 5A, Ra=2, Eb=20
Ans- Vt= Eb +IaRa
             = 20+5×2
             = 30v
8. 20v ,10A, 10rpm separately excited dc motar with armature resistance equal to 0.8 ohms . Calculate back emf developed in the motar when it operates on the full load 
Ans- Eb= Vt- I×Ra
              = 20 - 10×0.8
              = 20 - 8
              = 12v

9. Which barking  is not possible in series motar ?
Ans- Regenerative braking

10. The armature of the Dc shunt motar is proportional to 
Ans- Armature current only

11. A class 1 contactor should be mechanically servd to withstand 
Ans- 0.025 million times 

12. Which of the following pair is used for frequency converter 
Ans- squarel cage induction motor and wound rotar induction motor

13. In the jaw crushers, a motar has to often start against 
Ans- Heavy load

14. Which of the following motar is preferred for synthetic fiber mills
Ans- Reluctance motar

15. The Power factor of the reluctance motar at full load is
Ans-. 0.6 to 0.7

Wish you your exam goging very good 

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