Question 1 of 33

1. What is IGBT in VF drive?

D.C bus switching device

Inverter switching device

Rectifier switching device

Field supply switching device

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Question 2 of 33

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

By increasing the field current

By reducing the field current

By controlling the armature voltage

By reducing the armature current

Question 2 of 33

Question 3 of 33

3. What is the disadvantage of DC drive?

Not suitable for high speed operation

More complex with a single power conversion

More expensive than AC drive for high capacity motor

Installation of DC drives is more complicated

Question 3 of 33

Question 4 of 33

4. 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 4 of 33

Question 5 of 33

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

Speed sensing

Resistance temperature detector

Opto coupler

Photo voltaic cell

Question 5 of 33

Question 6 of 33

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

Power circuit and control circuits are simple

Fast response and wide speed range of control

Requires less space

Installation and running cost is less

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Question 7 of 33

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

Conveyors

Centrifugal pumps

Elevators

Hoists

Question 7 of 33

Question 8 of 33

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

AC voltage controller

Slip controller

DC chopper controller

Rectifier controller

Question 8 of 33

Question 9 of 33

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

To display the data direction of rotation forward/REV

To change the parameter setting

To store the entered data and factory stored data

To display the data status of frequency and current

Question 9 of 33

Question 10 of 33

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

Protects from mechanical injuries

Good appearance

Eliminates the electrical interference

Easy for connection

Question 10 of 33

Question 11 of 33

11. 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 OFF → REV → ON

Press ON → REV → OFF → ON

Press ON → REV → ON

Question 11 of 33

Question 12 of 33

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

High starting torque

Having lighter gauge winding

Robust in construction

No brushes and commutation

Question 12 of 33

Question 13 of 33

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

Field current

Back e.m.f

Terminal voltage

Armature current

Question 13 of 33

Question 14 of 33

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

Monitor the parameter

Indicate the fault

Display availability of supply

Display the speed

Question 14 of 33

Question 15 of 33

15. 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 15 of 33

Question 16 of 33

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

Armature control

Field control

Drives control

Voltage control

Question 16 of 33

Question 17 of 33

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

Indicate the status of drive

Indicate the incorrect operation of BOP

Monitor the parameter of AC drive

Indicate the display error in reading

Question 17 of 33

Question 18 of 33

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

Smoothening incoming A.C supply

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

Controls the power delivered to the motor

Stabilize the output voltage from the rectifier

Question 18 of 33

Question 19 of 33

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

Air Compressor

Rolling machine

Heavy duty electric drilling machine

Shearing machine

Question 19 of 33

Question 20 of 33

20. 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 20 of 33

Question 21 of 33

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

Field supply unit (FSU)

Microprocessor based electronic device

COMMS technology box

Speed feedback technology box

Question 21 of 33

Question 22 of 33

22. 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 22 of 33

Question 23 of 33

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

Servo controlled voltage stabilizer

Frequency multiplier

Cyclo converters

Phase sequence indicator

Question 23 of 33

Question 24 of 33

24. 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 detects the overloading condition of motor

It sounds an alarm in no load conditions

Question 24 of 33

Question 25 of 33

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

Very high starting torque

Maintenance free long life

Robust in construction

Easy to operate

Question 25 of 33

Question 26 of 33

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

Maintain the rotor current minimum

Keep the stator flux maximum

Maintain the speed of motor constant

Maintain the rated torque at all speeds

Question 26 of 33

Question 27 of 33

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

Speed Vs torque characteristic

Field current Vs armature current characteristic

Torque Vs field current characteristic

Speed Vs armature current characteristic

Question 27 of 33

Question 28 of 33

28. What is electric drive?

A device used as prime mover for generator

A device converts A.C to D.C supply

A machine converts mechanical energy into electrical

An electro mechanical device for controlling motor

Question 28 of 33

Question 29 of 33

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

Group drive

Individual drive

Continuous duty drive

Manual drive

Question 29 of 33

Question 30 of 33

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

Stop the motor

Restart the motor

Inching operation

Reverse the direction of motor

Question 30 of 33

Question 31 of 33

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

By increasing the field current

By increasing the supply voltage

By reducing the field current

By reducing the armature voltage

Question 31 of 33

Question 32 of 33

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

Automatic control drive

Variable position control drive

Intermittent duty drive

Short time duty drive

Question 32 of 33

Question 33 of 33

33. What is the function of VSI drives?

Converts A.C to D.C

Converts D.C to A.C

Converts A.C to A.C

Converts D.C to D.C

Question 33 of 33