Sub: Induction Synchronous and Special Electrical Machines
Chapter wise some important question:
1. (a) Describe with neat sketch the construction of a three-phase cage type induction motor. (b) Classify three phase induction motor and compare it.
2. Define slip. Why cannot an induction motor run at synchronous speed? Or what is the significance of slip? Deduce and expression for the frequency of rotor current in an induction motor.
3. Explain the method of producing rotating magnetic field by a three phase system in induction motor. Or. Explain graphically / analytically what will be the nature of magnetic field in the air gap when a balanced three phase supply is given to the three phase induction motor. (b) draw and explain the torque – slip and torque – speed characteristics of an induction motor indicating the starting torque maximum torque and the operating torque.How do starting and maximum torque very with the rotor resistance?
4. (a) Derive an expression for the torque of a three phase induction motor and find out the maximum torque.(b) Explain the working principle of a 3 phase induction motor.
5. (a) What is the significance of starter in three phase induction motor? Or Explain why an induction motor draws high current as compared to its full load current at starting. (b) Explain the working of any one starter to start the three phase induction motor with necessary circuits. Or explain the working of a fully automatic star delta starter with control circuit and power circuit.
6. (a) classify and explain the breaking method of preface induction motor. (b) what is locking tendency of induction mot? Describe crowling of three phase induction motor.
7. (a) And explain the phasar diagram of a three phase induction motor for lagging power factor. (b) Draw the power flow diagram of three phase induction motor and explain it. Or what are the various losses in an induction motor. On what factor do they depend?
8. (a) Draw the equivalent circuit of a induction motor.(b) Describe induction generator.
Single Phase Induction Motor:
1. (a) Explain double revolving field theory for single phase induction motor. (b) Explain the function and construction of capacitor start single phase induction motor.
2. (b) Is single phase induction motor is self starting? Justify your statement. (b) Describe the construction working and application ofsplit phase induction motor.
3. (a) Mention the application of single phase induction motors. (b) Describe the construction and principle of operation of capacitor run motor.
4. Describe the construction working and application of reluctance motor. Explain how AC series motor is constructed. State its application.
Alternator or Synchronous Generator:
1. (a) Why is a rotating field system two way stationary field? Or. Which type of armature is used in AC generator? Justify your answer. (b) Describe the working principle of synchronous machine in short.
2. (a) Deduce EMF equation of analternator. (b) Classify the alternator and differentiate between salient pole and non salient pole rotor construction of an alternator.
3. (a) What is synchronous reactance? Describe the voltage regulation of alternator (b) Explain the synchronous impedance method of determining regulation of an alternator. What is short circuit ratio of a synchronous machine?
4. (a) Explain the method of excitation system of alternator. (b) What is armature reaction? State the effect of armature reaction at various power factors.
5. (a) Draw the phasor diagram of an alternator at leading, lagging and unity power factor load. ( b) Describe the construction of synchronous machine with neat sketch in short.
6. (a)What is the reason of parallel operation? Enlist the condition of of parallel operation. (b)Describe synchronization method by synchroscope.
Synchronous Motor:
1. (a) Explain the principle of operation of a 3- phase synchronous motor. (b) Describe pull in , pull out and starting torque.
2. (a) Explain the application of synchronous motor as synchronous condenser. (b) What is the purpose of damper windings in a synchronous machine? What is hunting and phase swing of synchronous motor?
3. (a) Draw and describe the V- curves and inverted V-curves of synchronous motor. (b)Explain why a synchronous motor does not have starting torque.
Fractional horse power (FHP) Motors:
1. Write short note: (a) reluctance motor (b) Stepper motor (c) Servo motor (d) BLDC motor
2. Explain construction and working principle of synchronous reluctance motor. (b) Write the applications of servo motor and stepper motor.
No comments:
Post a Comment