Electrical Drives and Controls (EDC) solved MCQs

1 of 15

1. Which motor is preferred for Jaw crushers?

a. wrim

B. scim

c. belt slip ring im

d. dc shunt motor

2. A high starting torque is offered by the Belt Conveyors.

a. true

B. false

3. Which starting method is the worst method in Induction motor?

a. direct online starting

B. autotransformer starting

c. reactance starting

d. star-delta starting

4. Explanation: Intermittent duty cycle has frequent on load and off-loads period. The on-load period and off-loads periods are too

a. frequency changer

B. frequency remover

c. time period remover

d. dc machine

5. The capacity of the Crane is expressed in terms of tonnes.

a. true

B. false

6. 1800 second rated motors are used for

a. heavy duty cranes

B. light duty cranes

c. medium duty cranes

d. intermittent duty cranes

7. Calculate the frequency of the rotor side of the IM if the value of slip is 0.34 and the supply frequency is 70 Hz.

a. 23.8 hz

B. 22.7 hz

c. 24.5 hz

d. 23.1 hz

8. frequency is 2 Hz.

a. 50 hz

B. 49 hz

c. 45 hz

d. 51 hz

9. values of the capacitor and inductor are 4 F and 4 H.

a. .25 rad/sec

B. .26 rad/sec

c. .28 rad/sec

d. .29 rad/sec

10. Calculate the value of the angular acceleration of the Heavy duty crane using the given data: J = 5 kg-m2, load torque = 30 N-m, motor torque = 80 N-m.

a. 10 rad/s2

B. 20 rad/s2

c. 30 rad/s2

d. 50 rad/s2

11. motor torque = 2 N-m.

a. 45 rad/s2

B. the machine will fail to start

c. 30 rad/s2

d. 51 rad/s2

12. The direction of the single-phase IM can be reversed by using which one of the method?

a. by interchanging the supply terminals

B. by removing the capacitor

c. by changing the direction of auxiliary winding current

d. by removing the main winding

13. Which motor is preferred for overhead traveling cranes?

a. intermittent periodic motor

B. continuous duty motor

c. slow speed duty motor

d. short time rated motor

14. conditions where electric motors are being used?

a. thermography

B. geography

c. seismography

d. anthropology

15. What is the range of size of the motor (kW) for efficiency nearly equals to 90%?

a. 15-150

B. 0-2

c. 3-15

d. 150-250

16. Calculate the heat loss in the electric motor for time interval 0-5 sec using the following data: Ia=2 A, Ra=.8Ω.

a. 16 j-sec

B. 14 j-sec

c. 12 j-sec

d. 10 j-sec

17. sec.

a. .641

B. .334

c. .293

d. .417

18. Overloading can be prevented using

a. over-current protection

B. speed protection

c. over frequency protection

d. oversize protection

19. Full form of IDMT is  

a. inverse definite minimum time

B. inverter definite minimum time

c. inverter definite maximum time

d. insert definite minimum time

20. The most common cause of motor failure is

a. overloading

B. low resistance

c. contamination

d. over-heating

21. Full form of THD is  

a. total harmonic diverter

B. total harmonic digital

c. total harmonic distortion

d. total harmonic discrete

22. Calculate the compensator rating required for a sec(Φ)=1.

a. 0.64 p.u

B. 0.21 p.u

c. 0.57 p.u

d. 0 p.u

23. Calculate the value of Voltage ripple factor if the Form factor is 1.1.

a. 45.8 %

B. 46.2 %

c. 47.5 %

d. 49.9 %

24. Calculate the value of THD if the

a. 76 %

B. 75 %

c. 74 %

d. 73 %

25. Full form of VRF.

a. voltage ripple factor

B. voltage revert factor

c. volume ripple factor

d. volume revert factor


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