23041-Electrical Machine - 2 Important questions (Updated)

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

23041-ELECTRICAL MACHINES II

STAFF-IN-CHARGE: N.SURESH KUMAR

IMPORTANT QUESTIONS

UNIT-I

1.      Explain the constructional details of turbo alternator [OCT 2014] [APRIL 2015] [OCT 2015]

2.      Derive the EMF Equation of an Alternator. (12)[APRIL 2013] [OCT 2014]

3.      What are the advantages of Hydrogen cooling. (12)[OCT 2013] [APRIL 2015]

4.      Why cooling is necessary on alternators? Explain any one method of cooling of alternator. [APRIL 2014] [OCT 2015]

5.      Explain the basic principles of salient pole type alternator with the help of a neat diagram. (12) [OCT 2013]

6.      Explain the constructional details of stator and rotor of a salient pole Alternator with neat diagram.[APRIL 2013]

7.      Compare the constructional features of squirrel cage salient pole rotor with diagram (any 6 points)[APRIL 2014]

8.      Explain the methods adopted to obtain sine wave shape of emf induced in the alternator. [OCT 2014]

UNIT-II

1.    An alternator has the following data (i) 3 phase alternator (ii) no. of poles =8 (iii) distribution factor=.985 (iv) flux/pole=.040 Wb (v) no. of slots on the armature=90 (vi) no. of conductor/slot=8 (vii) full pitched winding (viii) speed of alternator=600rpm. Determine the no load terminal voltage. [OCT 2013] [APRIL 2014]

2.    Explain the synchronizing of alternator by dark lamp method.[APRIL 2013] [APRIL 2014] [OCT 2014]

3.    What are the causes of voltage drop in alternator? Draw the vector diagram of a loaded alternator and determine the voltage regulation.[APRIL 2013]

4.    Explain load sharing of two alternator[OCT 2013]

5.    Explain the synchronizing of alternator by bright lamp method. [OCT 2015]

6.    Explain the effects of changing excitation of alternator [OCT 2014]

7.    Explain the following i) synchronizing of alternator ii)Necessity of parallel operation of alternator iii) Advantages of parallel operation of alternator iv)Conditions of parallel operation of alternator [April 2015]

8.    Explain Armature reaction of an Alternator [APRIL 2015]

9.    Explain the vector diagrams of alternator for led lag and unity power factor [OCT 2015]

10.  Draw neat circuit diagram and briefly explain open circuit and short circuit test.

11.  An alternator has the following data (a). Number of phases is 3 (b)Number of slots on the Armature is 90 (c)Number of poles is10 (d)Number of conductor per slot is 8 (e)Distribution factor is 0.965 (f)full pitched winding (g)flux per pole is 0.040 wb (h)speed of alternator is 600 rpm (i)Connection is star. Determine No Load Terminal voltage.

UNIT-III

1.      Explain No load and Blocked rotor test of 3 phase induction motor. [OCT 2013] [APRIL 2014]

2.      Explain how rotating magnetic field is produced in 3 phase induction motor by explaining the principle of its operation by means of a neat diagram. [OCT 2013] [OCT 2014]

3.      Compare squirrel case and slip ring Induction Motor[APRIL 2013]

4.      Explain the construction and principle of operation of induction motor. [April 2015]

5.      Explain star delta starter with the help of the control diagram.[APRIL 2013] [APRIL 2014]

6.      Auto transformer starter [OCT 2014]

7.      DOL starter [APRIL 2015]

8.      Explain the speed control of induction motor by injected emf method  [OCT 2015]

9.      Condition for maximum starting torque of an induction motor  [OCT 2015]

10.  Explain Rotating Magnetic Field produced by 3 phase 2 pole system

11.  Explain Rotor Resistance starter with a neat diagram

UNIT-IV

1.      Explain the double field revolving theory for single phase induction motor with neat diagram and why 1 phase induction motor not self starting? [OCT 2013] [OCT 2014]

2.      Explain the different methods of starting of 3 phase synchronous motor [APRIL 2014] [April 2015]

3.      Explain principle of working Split Phase Induction Motor [APRIL 2013] [OCT 2015]

4.      Explain ‘V’ Curve and Inverted ‘V’ curve of synchronous motor.[APRIL 2013]

5.      Explain effect of excitation on armature current and power factor of a synchronous motor. [OCT 2013]

6.      Construction and principle of operation of a synchronous motor. [OCT 2014]

7.      Single phase capacitor start induction motor [APRIL 2014]

8.      Explain capacitor Start and Run Motor with a neat diagram [April 2015]

9.      Effect of change in excitation of synchronous motor. [OCT 2015]

UNIT-V

1.      Explain any six points to be followed in installation and commissioning of induction motor. [OCT 2013] [OCT 2014]

2.      Explain any one method of Oil Purification[APRIL 2013] [OCT 2014]

3.      Write any six points for the common troubles and their remedies for induction motor starters [APRIL 2013] [April 2015]

4.      Explain the following tests 1)Voltage test 2)continuity test 3)short circuit test [APRIL 2014] [April 2015]

5.      Working of single phase prevention relay [APRIL 2014]

6.      a)What are the transformer troubles? Explain their causes.

b)What are the transformer noises? Explain their remedies. [OCT 2015]

7.      What are the causes of noise and vibration of an Induction Motor [OCT 2013]

8.      Explain the causes and remedies for following motor troubles:

i)                    Motor starts in wrong direction

ii)                  Motor produces excessive noise

iii)                Rotor runs at half speed

iv)                Bearings are over hot  [OCT 2015]

9.      Explain Transformer Earthing and Measurement of Earth Resistance.

***ALL THE BEST ***