ELECTRICAL DRIVES AND CONTROLS Questions Bank 2014

ELECTRICAL DRIVES AND CONTROLS Questions Bank 2014

ME 1205 ELECTRICAL DRIVES AND CONTROLS

QUESTION BANK

PART-B

UNIT I

1. Explain the factors governing the selection of motors.

2. Discuss in detail the determination of power rating of motors.

(ii) Explain the choice of selection of the motor for different loads.

electric motor are made.

3. (i) Explain the different types of loading of drives.

4. (i) Describe the simplifications based on which the heating and cooling calculations of an

(ii) Establish the heating time constant and the heating curves.

5. (i) Compare the D.C and A.C drives.

(ii) Write a brief note on classes of duty for an electric motor in an electric drive.

6. Draw the typical temperature rise-time curve and derive the equation for temperature rise

7. Explain the loading of an electric motor and its duty cycle with a simple diagram.

8. Explain in detail about the various types of electric drives



UNIT II

1. (i) List out the advantages and disadvantages of electrical braking over mechanical breaking.

(ii) Discuss any one method of electrical braking of DC Machines.

2. Explain the Speed-Torque characteristics of three phase induction motor with neat diagrams.

3. Explain about the speed-torque characteristics of a DC Shunt Motor with suitable graph and equations.

4. Explain about the quadrantal diagram of speed-torque characteristics for a motor driving hoist load.

5. Explain how an induction motor is brought to stop by (i) Plugging and (ii) dynamic braking

6. Explain the various methods of braking of induction motors.

7. Draw and explain various load characteristics of DC Shunt Motor.

8. Explain Rheostat braking in DC Series Motor and Plugging in DC Shunt Motor.

9. Explain various methods of braking of DC Shunt Motors with neat diagrams.

10. Explain various methods of braking of DC Series Motors with neat diagrams.

11. (i) Explain the speed - torque curve of single phase induction motors in detail.

(ii) Explain the method of regenerative braking employed in DC Motors.

12. Explain about the speed-torque characteristics of a DC Compound Motor with suitable graph and equations.

UNIT III

1. Draw a neat schematic diagram of a three point starter and explain its working.

2. Draw a neat schematic diagram of a four point starter and explain its working.

3. Explain with neat circuit diagram, the star-delta starter method of starting squirrel cage motor.

4. Explain the typical control circuits for DC Series and Shunt motors

5.Explain the different starting methods of three phase squirrel cage motors with neat sketches.

6. Explain different methods of starting of DC Motors.

7. Explain with neat diagram the starting of three phase slip ring induction motor.

8. Draw and explain the push-button operated direct-on line starter for three phase motor.

9. Draw and explain the manual auto-transformer starter for three phase induction motor.



UNIT IV

1. Explain with neat sketch the chopper control method of speed control of DC Motors.

2. Explain with neat sketches about the DC Shunt Motor speed control by using single phase fully controlled bridge converter.

3. Discuss the Ward-Leonard speed control system with a neat circuit. Also mention its advantages and disadvantages.

4. Explain how the speed of a DC Shunt Motor can be varied both above and below the

speed at which it runs with full field current.

5. (i) Explain with neat sketch the operation of chopper fed DC Series Motor drive. Also,

derive the expression for average motor current.

(ii) Explain Time ratio control and Current limit control.

6. Explain the speed control schemes of DC Series Motor.

7. Explain the different methods of speed control employed in DC Shunt Motor.

8. Explain the control of DC drives using rectifiers and choppers.

9. Explain the single phase half wave converter drive speed control for DC drive with waveforms.

10. Explain in detail the single phase semi-converter speed control for DC drive for

separately excited motor.

UNIT V

1. Draw the power circuit arrangement of three phase variable frequency inverter for the speed control of three phase induction motor and explain its working.

2. Explain the V/f control method of AC drive with neat sketches.

3. Discuss the speed control of AC motors by using three phase AC Voltage regulators

4. Explain the speed control schemes of phase wound induction motors.

5. Explain the concatenation operation of three phase induction motors. Hence derive the

speed experienced for the cascaded set.

6. Explain in detail about Slip power recovery scheme.

7. Explain the different methods of speed control used in three phase induction motors.

8. Explain the working of following methods with neat circuit diagram.

i) Kramer system ii) Scherbius system

9. Explain in detail rotor resistance method of speed control of a slip ring induction motor.

10. (i) Explain the operation of Pole changing method of speed control.

(ii) Explain the pole amplitude modulation method.

11. Explain the static Kramer method and static scherbius method of speed control of three phase induction motor.

12. Explain in detail about the various methods of solid state speed control techniques by

using inverters.

13. Explain the solid state stator voltage control technique for the speed control of three

phase induction motor.

14. Explain the various methods of speed control of a three phase induction motor when

Fed through semiconductor devices.