MCQ or Objective Questions on Electric Machines 3

1. The degree of compounding for a dc compound generator is determined by

Under construction.

2. Stray losses of dc machine are affected by

Under construction.

3. In synchronous motor inverted V curve represents the relation between

Under construction.

4. A 4 pole, 50 Hz induction motor is found to be running on full load at a slip of 5 % . The speed of the motor will be

Ns = 120f / P = 1500 rpm.
N = ( 1 - s )Ns = 1425 rpm.

5. Direction of rotation of dc motor is changed by which of the following methods?

Under construction.

6. What is the distribution factor for 108 slot, 12 pole , 3 - Φ winding?

Under construction.

7. A three stack stepper motor has 8 teeth on stator as well as on rotor. Determine the step size when each stack is excited at a time?

Step size = 360 / ( 8 × 3 ) = 15°.

8. What is the rotating part of a DC motor?

Under construction.

9. What is used to develop the magnetic field in small sized DC motor ?

Under construction.

10. In DC motor torque is generated by which principle?

Under construction.

11. In DC series motor

Under construction.

12. What is universal motor?

Under construction.

13. In DC shunt motor

Under construction.

14. Can you tell that where DC shunt motors are used?

Under construction.

15. Can you tell where DC series motors are used ?

Under construction.

16. Which of the following applications needs high starting torque ?

Under construction.

17. Select DC motor that is preferred for cranes and hoists ?

Under construction.

18. Two DC series motors when connected in series, draw a current of I Amp and run at N rpm. When those motors are connected in parallel and if the motors continue to draw current I, then the speed of the motors will be

Under construction.

19. Two DC series motors are connected in series to produce a torque T. Now if the motors are connected in parallel, the torque produced will be

Under construction.

20. Hopkins’s test is carried out at which condition?

Under construction.