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

Question 1 of 33

1. 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 direction of rotation forward/REV

To display the data status of frequency and current

To change the parameter setting

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Question 2 of 33

2. 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 2 of 33

Question 3 of 33

3. What is electric drive?

A device used as prime mover for generator

A device converts A.C to D.C supply

An electro mechanical device for controlling motor

A machine converts mechanical energy into electrical

Question 3 of 33

Question 4 of 33

4. 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 4 of 33

Question 5 of 33

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

Robust in construction

Maintenance free long life

Very high starting torque

Easy to operate

Question 5 of 33

Question 6 of 33

6. 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 6 of 33

Question 7 of 33

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

Armature current

Terminal voltage

Back e.m.f

Field current

Question 7 of 33

Question 8 of 33

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

Resistance temperature detector

Photo voltaic cell

Speed sensing

Opto coupler

Question 8 of 33

Question 9 of 33

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

Hoists

Conveyors

Centrifugal pumps

Elevators

Question 9 of 33

Question 10 of 33

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

Fast response and wide speed range of control

Power circuit and control circuits are simple

Installation and running cost is less

Requires less space

Question 10 of 33

Question 11 of 33

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

Microprocessor based electronic device

Speed feedback technology box

COMMS technology box

Field supply unit (FSU)

Question 11 of 33

Question 12 of 33

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

Group drive

Manual drive

Continuous duty drive

Individual drive

Question 12 of 33

Question 13 of 33

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

Voltage control

Field control

Drives control

Armature control

Question 13 of 33

Question 14 of 33

14. 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

Provides a constant voltage to the field winding of motor

Produces required firing current to the firing circuit

Question 14 of 33

Question 15 of 33

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

By increasing the supply voltage

By reducing the armature voltage

By increasing the field current

By reducing the field current

Question 15 of 33

Question 16 of 33

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

Cyclo converters

Phase sequence indicator

Servo controlled voltage stabilizer

Frequency multiplier

Question 16 of 33

Question 17 of 33

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

Controls the power delivered to the motor

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

Smoothening incoming A.C supply

Stabilize the output voltage from the rectifier

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Question 18 of 33

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

High starting torque

Interlocking system in industries

Control stepless speed in motors

Group drive motors

Question 18 of 33

Question 19 of 33

19. 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 19 of 33

Question 20 of 33

20. What is IGBT in VF drive?

Inverter switching device

Rectifier switching device

Field supply switching device

D.C bus switching device

Question 20 of 33

Question 21 of 33

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

Torque Vs field current characteristic

Field current Vs armature current characteristic

Speed Vs torque characteristic

Speed Vs armature current characteristic

Question 21 of 33

Question 22 of 33

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

Monitor the parameter of AC drive

Indicate the display error in reading

Indicate the incorrect operation of BOP

Indicate the status of drive

Question 22 of 33

Question 23 of 33

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

Maintain the rotor current minimum

Maintain the rated torque at all speeds

Keep the stator flux maximum

Maintain the speed of motor constant

Question 23 of 33

Question 24 of 33

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

Robust in construction

Having lighter gauge winding

High starting torque

No brushes and commutation

Question 24 of 33

Question 25 of 33

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

AC voltage controller

DC chopper controller

Slip controller

Rectifier controller

Question 25 of 33

Question 26 of 33

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

It reduce motor current during transient operation

It detects the overloading condition of motor

It maintain the torque at low voltage conditions

It sounds an alarm in no load conditions

Question 26 of 33

Question 27 of 33

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

Basic Operation Programme

Basic Operational Panel

Bridge Operation Panel

Bridge Operator Programme

Question 27 of 33

Question 28 of 33

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

Display the speed

Display availability of supply

Indicate the fault

Monitor the parameter

Question 28 of 33

Question 29 of 33

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

Short time duty drive

Variable position control drive

Intermittent duty drive

Automatic control drive

Question 29 of 33

Question 30 of 33

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

Rolling machine

Shearing machine

Heavy duty electric drilling machine

Air Compressor

Question 30 of 33

Question 31 of 33

31. What is the disadvantage of DC drive?

Installation of DC drives is more complicated

More complex with a single power conversion

More expensive than AC drive for high capacity motor

Not suitable for high speed operation

Question 31 of 33

Question 32 of 33

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

Inverter

Rectifier

D.C bus

A.C motor

Question 32 of 33

Question 33 of 33

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

Good appearance

Protects from mechanical injuries

Eliminates the electrical interference

Easy for connection

Question 33 of 33