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

Question 1 of 33

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

Indicate the incorrect operation of BOP

Indicate the status of drive

Indicate the display error in reading

Monitor the parameter of AC drive

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 a constant voltage to the field winding of motor

Produces required firing current to the firing circuit

Provides variable voltage to the field winding of motor

Question 2 of 33

Question 3 of 33

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

Individual drive

Manual drive

Group drive

Continuous duty drive

Question 3 of 33

Question 4 of 33

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

Maintain the rotor current minimum

Maintain the speed of motor constant

Maintain the rated torque at all speeds

Keep the stator flux maximum

Question 4 of 33

Question 5 of 33

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

Basic Operational Panel

Basic Operation Programme

Bridge Operation Panel

Bridge Operator Programme

Question 5 of 33

Question 6 of 33

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

Intermittent duty drive

Variable position control drive

Automatic control drive

Short time duty drive

Question 6 of 33

Question 7 of 33

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

By reducing the field current

By controlling the armature voltage

By increasing the field current

By reducing the armature current

Question 7 of 33

Question 8 of 33

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

It sounds an alarm in no load conditions

It detects the overloading condition of motor

It maintain the torque at low voltage conditions

It reduce motor current during transient operation

Question 8 of 33

Question 9 of 33

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

Inverter

A.C motor

Rectifier

D.C bus

Question 9 of 33

Question 10 of 33

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

Centrifugal pumps

Elevators

Hoists

Conveyors

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 armature voltage

By reducing the field current

By increasing the supply voltage

By increasing the field current

Question 11 of 33

Question 12 of 33

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

AC voltage controller

DC chopper controller

Slip controller

Rectifier controller

Question 12 of 33

Question 13 of 33

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

Smoothening incoming A.C supply

Controls the power delivered to the motor

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

Stabilize the output voltage from the rectifier

Question 13 of 33

Question 14 of 33

14. What is the disadvantage of DC drive?

More complex with a single power conversion

Installation of DC drives is more complicated

Not suitable for high speed operation

More expensive than AC drive for high capacity motor

Question 14 of 33

Question 15 of 33

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

Very high starting torque

Maintenance free long life

Easy to operate

Robust in construction

Question 15 of 33

Question 16 of 33

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

Voltage control

Field control

Drives control

Armature control

Question 16 of 33

Question 17 of 33

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

To change the parameter setting

To store the entered data and factory stored data

To display the data direction of rotation forward/REV

To display the data status of frequency and current

Question 17 of 33

Question 18 of 33

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

Stop the motor

Inching operation

Restart the motor

Reverse the direction of motor

Question 18 of 33

Question 19 of 33

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

COMMS technology box

Microprocessor based electronic device

Field supply unit (FSU)

Speed feedback technology box

Question 19 of 33

Question 20 of 33

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

High starting torque

No brushes and commutation

Robust in construction

Having lighter gauge winding

Question 20 of 33

Question 21 of 33

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

Frequency multiplier

Cyclo converters

Servo controlled voltage stabilizer

Phase sequence indicator

Question 21 of 33

Question 22 of 33

22. What is the function of VSI drives?

Converts A.C to A.C

Converts A.C to D.C

Converts D.C to D.C

Converts D.C to A.C

Question 22 of 33

Question 23 of 33

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

Display the speed

Monitor the parameter

Indicate the fault

Display availability of supply

Question 23 of 33

Question 24 of 33

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

Press ON → OFF → REV → ON

Press ON → REV → OFF → ON

Press ON → REV → ON

Press OFF → REV → ON

Question 24 of 33

Question 25 of 33

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

Armature current

Back e.m.f

Field current

Terminal voltage

Question 25 of 33

Question 26 of 33

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

Good appearance

Eliminates the electrical interference

Easy for connection

Protects from mechanical injuries

Question 26 of 33

Question 27 of 33

27. What is electric drive?

A machine converts mechanical energy into electrical

A device used as prime mover for generator

A device converts A.C to D.C supply

An electro mechanical device for controlling motor

Question 27 of 33

Question 28 of 33

28. 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

Power circuit and control circuits are simple

Requires less space

Question 28 of 33

Question 29 of 33

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

Control stepless speed in motors

Interlocking system in industries

High starting torque

Group drive motors

Question 29 of 33

Question 30 of 33

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

Heavy duty electric drilling machine

Air Compressor

Shearing machine

Rolling machine

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

Speed Vs armature current characteristic

Field current Vs armature current characteristic

Torque Vs field current characteristic

Question 31 of 33

Question 32 of 33

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

Resistance temperature detector

Opto coupler

Photo voltaic cell

Speed sensing

Question 32 of 33

Question 33 of 33

33. What is IGBT in VF drive?

Field supply switching device

D.C bus switching device

Inverter switching device

Rectifier switching device

Question 33 of 33