Most Asked Objective Questions or MCQ on D.C. Motors for Electrical Engineering

Multiple Choice Questions (MCQ) on D.C. Generators for Electrical Engineering


MCQ on D.C. Motors for Electrical Engineering

1. The direction of rotation of a D.C. series motor can be changed by 
(a) interchanging supply terminals 
(b) interchanging field terminals 
(c) either of (a) and (b) above 
(d) None of the above 

Ans: b

2. Which D.C. motor is preferred for elevators ? 
(a) Shunt motor 
(b) Series motor 
(c) Differential compound motor 
(d) Cumulative compound motor 

Ans: d



3. The speed of a D.C. shunt motor more than its full-load speed can be obtained by 
(a) decreasing the field current 
(b) increasing the field current 
(c) decreasing the armature current 
(d) increasing the armature current

 Ans: a

4. By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor? 
(a) Frame 
(b) Shaft 
(c) Commutator 
(d) Stator 

Ans: c

5. In which of the following applications D.C. series motor is invariably tried? 
(a) Starter for a car 
(b) Drive for a water pump 
(c) Fan motor 
(d) Motor operation in A.C. or D.C. 

Ans: a

6. In D.C. machines fractional pitch winding is used 
(a) to improve cooling 
(b) to reduce copper losses 
(c) to increase the generated e.m.f. 
(d) to reduce the sparking 

Ans: d

7. A three point starter is considered suitable for 
(a) shunt motors 
(b) shunt as well as compound motors 
(c) shunt, compound and series motors 
(d) all D.C. motors 

Ans: b

8. In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be 
(a) 100% 
(b) around 90% 
(c) anywhere between 75% and 90% 
(d) less than 50% 

Ans: d

9. The power mentioned on the name plate of an electric motor indicates 
(a) the power drawn in kW 
(b) the power drawn in kVA 
(c) the gross power 
(d) the output power available at the shaft 

Ans: d

10. D.C. series motors are used 
(a) where load is constant 
(b) where load changes frequently 
(c) where constant operating speed is needed 
(d) in none of the above situations. 

Ans: d

11. For which of the following applications a D.C. motor is preferred over an A.C. motor ? 
(a) Low speed operation 
(b) High speed operation 
(c) Variable speed operation 
(d) Fixed speed operation 

Ans: c

12. In D.C. machines the residual magnetism is of the order of 
(a) 2 to 3 per cent 
(b) 10 to 15 per cent 
(c) 20 to 25 per cent 
(d) 50 to 75 per cent 

Ans: a



13. Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors ? (a) Low cost 
(b) Wide speed range 
(c) Stability 
(d) High starting torque. 

Ans: a

14. Which of the following motors is usually used in house-hold refrigerators ? 
(a) D.C. shunt motor 
(b) D.C. series motor 
(c) Single phase induction motor (split phase start or induction run motor) 
(d) Reluctance motor 
(e) Synchronous motor 

Ans: c

15. D.C. generators are normally designed for maximum efficiency around 
(a) full-load 
(b) rated r.p.m. 
(c) rated voltage 
(d) all of the above 

Ans: a

16. In a D.C. generator, the iron losses mainly take place in 
(a) yoke 
(b) commutator 
(c) armature conductors 
(d) armature rotor 

Ans: d

17. D.C. generators are installed near the load centres to reduce 
(a) iron losses 
(b) line losses 
(c) sparking 
(d) corona losses 

Ans: b

18. Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity ? 
(a) Swinburne’s test 
(b) Hopkinson’s test 
(c) Field test 
(d) Brake test 

Ans: c

19. Hopkinson’s test on D.C. machines is conducted at 
(a) no-load 
(b) part load 
(c) full-load 
(d) overload 

Ans: c

20. During rheostat braking of D.C. series motors 
(a) motor is run as a generator 
(b) motor is reversed in direction 
(c) motor is run at reduced speed 

Ans: a

21. For which types of D.C. motor, dynamic braking is generally used ? 
(a) Shunt motors 
(b) Series motors 
(c) Compound motors 
(d) All of the above 

Ans: d

22. Which method of braking is generally used in elevators ? 
(a) Plugging 
(b) Regenerative braking 
(c) Rheostatic braking 
(d) None of the above 

Ans: a

23. One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven 
(a) runs as a generator 
(b) does not run as a generator 
(c) also runs as a motor comes to stop after sometime 

Ans: a


Tags- 
#MCQ on electrical engineering
#electrical engineering mcq with answer
#D.C. Motors mcq
Share:

0 comments:

Post a Comment

Popular Posts

About

ElectricalNotes4u is a Blog for Electrical Engineering Students who want to learn Electrical Engineering online. We will Provide You Notes on all Major subject of electrical engineering. We also Provide Important MCQ that will help you to Prepare for Competitive Exam.