Chapter 1: Poly-phase IM and
1) Explain the difference between squirrel-cage and slip-ring I.M?
2) Which methods are used for the speed control of 3-Phase Induction Motor?
3) Explain the working Principle and advantage of Double cage squirrel cage I.M?
4) Derive the equation of electromagnetic torque for a three phase induction motor with usual notations from first principles.
5) What is harmonic torques? Explain cogging and crawling in 3-phase induction motor with their remedies.
6) What is slip? Explain torque-slip and torque-speed curve of an induction motor. Describe the stable and unstable region.
7) Mention the types of starters for a three phase induction motor. Explain star-delta, DOL and Auto transformer starters in detail.
8) Explain the procedure to construct the circle diagram of induction motor. Also describe the method to determine losses, efficiency and slip at full load condition using circle diagram.
9) Briefly describe the construction and working of linear induction motor.
10) Derive the condition for maximum starting torque for three phase induction motor.
11) Discuss the procedure to perform no load and blocked rotor tests on a three phase induction motor.
12) Explain any one method for starting of 3phase squirrel cage induction motor.
13) Explain the methods of slip measurement in 3-phase induction motor.
14) A 3-phase 400/200V, Y-Y connected wound rotor has 0.06 Ω rotor resistance and 0.3 Ω standstill reactance per phase. Find additional resistance required in rotor circuit to make the starting torque equal to maximum torque of motor.
15) Effect of rotor resistance on performance of motor.
16) Explain the working Principle of 3-Phase Induction Motor. Derive the emf equation of Induction motor.
17) Explain construction of 3-Phase Induction Motor.
18) The power input to a 500 V, 50 Hz, 6 Pole, 3 phase Induction Motor running at 975 rpm is 40 KW. The stator losses are 1 KW and the friction and windage losses total 2 KW. Calculate (i) the slip (ii) the rotor copper loss (iii) shaft power and (iv) the efficiency.
19) A 100 KW (output), 3300 V, 50 Hz, 3-phase star connected induction motor has synchronous speed of 500 RPM. The full load slip is 1.8% and full load power factor is 0.85. Stator cu loss = 2440 W, Iron loss = 3500 W, Rotational loss = 1200 W. Calculate (1) rotor cu loss, (2) Line current and (3) full load efficiency.
20) Draw the phasor diagram (vector diagram) for a three phase induction motor and justify the statement “Power factor of the motor improves from no load to full load”.
21) Discuss the procedure to perform no-load and blocked-rotor tests on a three phase induction motor.
22) Explain Maximum starting torque condition in induction motor.
23) A 10 pole, 3 phase, 600 V, 50 Hz star connected induction motor has rotor resistance and standstill reactance of 0.03 and 0.5 ohms per phase respectively. Find (a) Speed at maximum torque (b) the ratio of full load torque to maximum torque, if the full load speed is 570 rpm.
24) A 3 phase, 50 Hz, 500 V, I.M. with 8 poles gives an output of 30 kW at 700rpm with 0.8 PF lagging. The mechanical losses are equal to 1 kW. Find (1) slip (2) rotor copper loss (3) input if the stator losses are 1200 W and (4) line current.
25) Prove that when 3 phase supply is applied across the stator of 3 phase IM, a rotating magnetic field of constant magnitude is produced.
Chapter 2 : Induction Generator
1) Explain the working principle of Induction generator.
Chapter 4: Alternator or Synchronous Generator
1) Define voltage regulation of alternator. OR What is voltage regulation? Explain any one method to find the voltage regulation. OR List the methods of determination of voltage regulation of an alternator. Explain any one in detail. OR Explain any one method to find the voltage regulation of an alternator.
2) Explain concept of pitch factor and distribution factor in case of an alternator. How these values change with harmonics.
3) Describe the effect of armature reaction on alternator. OR Describe the effect of armature reaction with zero lagging power factor in case of a synchronous generator.
4) Differentiate between cylindrical and salient pole synchronous machine.
5) What is synchronization? OR What is synchronization? Explain two bright and one dark lamp method of synchronization of 3 phase alternators.
6) Derive emf equation of an alternator. OR Derive the EMF equation of alternator from first principles. OR Derive the emf equation of an alternator. Just define the pitch factor and distribution factor.
7) State the conditions to be satisfied for putting a 3 phase alternator in parallel with infinite bus. OR Explain the parallel operation of two alternators.
8) Explain slip test to find Xd and Xq of salient pole synchronous machines. Draw circle diagram. OR Explain the construction of a salient pole synchronous machine.
9) Explain hunting in synchronous machines.
10) What are the causes of harmonics in the voltage waveform of an alternator? How can these be minimized?
11) Explain the two reaction theory of salient pole synchronous machines.
12) A 1200 KVA, 6600 V, 3 phase star connected alternator has its armature resistance as 0.25 Ω per phase and its synchronous reactance as 5 Ω per phase. Calculate its regulation if it delivers full load at (i) 0.8 power factor lagging and (ii) 0.8 power factor leading.
13) A 100 kVA, 3000 V, 50 Hz, 3 phase star connected alternator has effective armature resistance of 0.2 ohm. The field current of 40 A produces short circuit current of 200 A and an open circuit voltage of 1040 V (line value). Find the full load voltage regulation at 0.85 PF lagging and 0.85 PF leading.
Chapter 6: Commutator Motor
1) Explain the construction and working of universal motor. OR Explain the construction and working of Repulsion motor. OR Discuss working of Repulsion motor and Universal Motor.
2) What is the role of commutator in A.C. commutator motor? Explain working of Schrage Motor.
No comments:
Post a Comment