ELECTRICIAN 2nd YEAR MODULE – AC / DC Motor Drives ONLINE TEST

Question 1 of 33

1. Which device controls the speed of A.C motor in A.C drive?

Field supply unit (FSU)

COMMS technology box

Microprocessor based electronic device

Speed feedback technology box

Question 1 of 33

Question 2 of 33

2. What is the function of Field Supply Unit (FSU) in DC drive?

Provides a constant voltage to the armature of the motor

Provides variable voltage to the field winding of motor

Produces required firing current to the firing circuit

Provides a constant voltage to the field winding of motor

Question 2 of 33

Question 3 of 33

3. What is the purpose of JOG key in control panel of D.C drive?

Inching operation

Restart the motor

Stop the motor

Reverse the direction of motor

Question 3 of 33

Question 4 of 33

4. Which is the application of single quadrant loads operating in first quadrant in drives?

Hoists

Centrifugal pumps

Elevators

Conveyors

Question 4 of 33

Question 5 of 33

5. What is the function of IGBT in AC drive?

Stabilize the output voltage from the rectifier

Smoothening incoming A.C supply

Converts incoming A.C power into D.C power output

Controls the power delivered to the motor

Question 5 of 33

Question 6 of 33

6. What is the purpose of LCD in Basic Operator Panel (BOP) in AC drive?

Monitor the parameter of AC drive

Indicate the status of drive

Indicate the incorrect operation of BOP

Indicate the display error in reading

Question 6 of 33

Question 7 of 33

7. What is the function of VSI drives?

Converts A.C to D.C

Converts D.C to D.C

Converts D.C to A.C

Converts A.C to A.C

Question 7 of 33

Question 8 of 33

8. What is the full form of B.O.P in D.C drive?

Bridge Operator Programme

Bridge Operation Panel

Basic Operational Panel

Basic Operation Programme

Question 8 of 33

Question 9 of 33

9. Which is the correct sequence operation of key button in BOP of AC drive to change the direction of rotation?

Press ON → REV → OFF → ON

Press ON → REV → ON

Press OFF → REV → ON

Press ON → OFF → REV → ON

Question 9 of 33

Question 10 of 33

10. What is the name of the component marked as 'X' in the block diagram of AC drive?

A.C motor

Rectifier

Inverter

D.C bus

Question 10 of 33

Question 11 of 33

11. How can the base speed of D.C shunt motor be increased by using D.C drive?

By reducing the field current

By increasing the supply voltage

By increasing the field current

By reducing the armature voltage

Question 11 of 33

Question 12 of 33

12. What is the main use of A.C drive?

Control stepless speed in motors

High starting torque

Interlocking system in industries

Group drive motors

Question 12 of 33

Question 13 of 33

13. Why are A.C drives mostly used in process plants?

Robust in construction

Maintenance free long life

Easy to operate

Very high starting torque

Question 13 of 33

Question 14 of 33

14. Which drive is classified according to mode of operation?

Group drive

Manual drive

Individual drive

Continuous duty drive

Question 14 of 33

Question 15 of 33

15. Why is it necessary to keep V/F ratio constant in a drive?

Maintain the speed of motor constant

Keep the stator flux maximum

Maintain the rated torque at all speeds

Maintain the rotor current minimum

Question 15 of 33

Question 16 of 33

16. What is the reason for using shielded cable for connecting low level signal circuits in DC drives?

Easy for connection

Protects from mechanical injuries

Good appearance

Eliminates the electrical interference

Question 16 of 33

Question 17 of 33

17. Which is proportional to the torque in D.C motor?

Field current

Terminal voltage

Armature current

Back e.m.f

Question 17 of 33

Question 18 of 33

18. What is the purpose of LCD on basic operator panel in D.C drive?

Indicate the fault

Monitor the parameter

Display availability of supply

Display the speed

Question 18 of 33

Question 19 of 33

19. What is the advantage of AC drive compared to DC drive?

Fast response and wide speed range of control

Installation and running cost is less

Requires less space

Power circuit and control circuits are simple

Question 19 of 33

Question 20 of 33

20. Why are A.C drives better suited for high speed operation?

High starting torque

Robust in construction

No brushes and commutation

Having lighter gauge winding

Question 20 of 33

Question 21 of 33

21. Which control system is used for Eddy current drives?

Slip controller

DC chopper controller

Rectifier controller

AC voltage controller

Question 21 of 33

Question 22 of 33

22. What is the function of power controller in drive circuits?

It reduce motor current during transient operation

It maintain the torque at low voltage conditions

It sounds an alarm in no load conditions

It detects the overloading condition of motor

Question 22 of 33

Question 23 of 33

23. What is the disadvantage of DC drive?

More complex with a single power conversion

More expensive than AC drive for high capacity motor

Not suitable for high speed operation

Installation of DC drives is more complicated

Question 23 of 33

Question 24 of 33

24. How can constant torque be obtained from armature and field controlled drives?

By controlling the armature voltage

By reducing the armature current

By increasing the field current

By reducing the field current

Question 24 of 33

Question 25 of 33

25. Which type of machine in industries is provided with multi-motor electric drive?

Shearing machine

Heavy duty electric drilling machine

Air Compressor

Rolling machine

Question 25 of 33

Question 26 of 33

26. Which power modulator is used in the electric drive system?

Frequency multiplier

Phase sequence indicator

Servo controlled voltage stabilizer

Cyclo converters

Question 26 of 33

Question 27 of 33

27. Which control system consumes very low power for motion control in AC and DC motors?

Voltage control

Field control

Drives control

Armature control

Question 27 of 33

Question 28 of 33

28. What is electric drive?

A device converts A.C to D.C supply

An electro mechanical device for controlling motor

A device used as prime mover for generator

A machine converts mechanical energy into electrical

Question 28 of 33

Question 29 of 33

29. Which is the classification of drive according to dynamics and transients?

Automatic control drive

Intermittent duty drive

Short time duty drive

Variable position control drive

Question 29 of 33

Question 30 of 33

30. What is the purpose of PROG/DATA button in BOP of AC drive?

To store the entered data and factory stored data

To display the data status of frequency and current

To change the parameter setting

To display the data direction of rotation forward/REV

Question 30 of 33

Question 31 of 33

31. What is the name of the characteristic curve in D.C drive?

Speed Vs torque characteristic

Torque Vs field current characteristic

Field current Vs armature current characteristic

Speed Vs armature current characteristic

Question 31 of 33

Question 32 of 33

32. Which type of sensing unit is employed in drive systems?

Opto coupler

Resistance temperature detector

Speed sensing

Photo voltaic cell

Question 32 of 33

Question 33 of 33

33. What is IGBT in VF drive?

Rectifier switching device

Inverter switching device

D.C bus switching device

Field supply switching device

Question 33 of 33