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Diploma SSC-JE ELECTRICAL FULL TEST | MM 120 | TIME  60 MIN.| NEGATIVE 50%

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

Match List I (type of single-phease motor) with List II (type of appliance) and select the correct answer using the codes given below the lists.
              List  I                                    List II
P. Permanent  magnet   1. Rocket type         
Q. Shaded pole               2.Refrigerator compressor
R. Universal                   3. Sewing machine
S. Capacitor-shunt,       4. Photocopy machine
   capacitor-run
  induction motor

Codes
      P   Q   R   S
a.
1   2   3   4
b.
1   2   4   3
c.
4   1   3   2
d.
1   4   3   2
 

 2. 

Two transformers operating in parallel will share the load accoring to their 
a.
leakage reactance
b.
pu impedance
c.
efficiency
d.
rating
 

 3. 

A 2400/240 V,200 kVA single-phase transformer has a core loss of 1.8 kW at rated voltage .Its equivalent resistance is 1.1 % .Then ,the transformer efficiency at 0.9 pF and on full load is
a.
97.57 %
b.
98.05%
c.
97.82%
d.
95.56%
 

 4. 

In a transformer,if the iron and copper losses are 40.5 kW and 50 kW respectively ,then at what fraction of load the efficiency will be maximum ?
a.
0.8
b.
0.57
c.
0.70
d.
0.9
 

 5. 

As the load on transformer is increased, the core losses 
a.
decrease slightly
b.
increase slightly
c.
remain constant
d.
may decrease or increase slightly depending upon the nature of load
 

 6. 

Two  transformers of different kVA rating working in parallel , share the load in proportion to thier ratings when their
a.
per unit leakage impedances on the same kVA base are the same
b.
per unit leakage impedances on their respective ratings are equal
c.
ohmic values of the leakage impedances are inversely proportional to their ratings
d.
ohmic values of the magnetising reactances are the same
 

 7. 


mc007-1.jpg
a.
86.7 %
b.
88.26 %
c.
88.9 %
d.
87 .8 %
 

 8. 

Macth List I (the windings the large DC series motor ) with List II (their fuctions ) and find the correct answer using codes given below the lists.
                List I                                List II
     P.Series field winding       1. To avoid field distortion
                                                        under the pole
     Q. Shunt field winding      2. To avoid sparking
     R. Commutating pole         3. To generate working flux
                                                    winding 
     S. Compensating windings   4. To aviod runway
                                                       speeds on on load

Codes
      P   Q   R   S
a.
3   4   2   1
b.
4   3   2   1
c.
2   3   1   4
d.
1   2   4   3
 

 9. 

A 400 V, 15 kW , 4-poles, 50 Hz Y-connected induction motor has full load silp of 4% . The ouput torque of the machine at full load is
a.
1.66 N-m
b.
95.50 N-m
c.
99.47 N-m
d.
624.73 N-m
 

 10. 


mc010-1.jpg
a.
slip frequency
b.
supply freuency
c.
frequency corresponding to rotor speed
d.
zero
 

 11. 


mc011-1.jpg
a.
time harmonics
c.
slot harmonics  
b.
space harmonics
d.
reverse rotating fields
 

 12. 


mc012-1.jpg
a.
generating
b.
breaking
c.
motoring
d.
None of these
 

 13. 


mc013-1.jpg
a.
mc013-3.jpg
b.
mc013-4.jpg
c.
mc013-5.jpg
d.
mc013-6.jpg
 

 14. 


mc014-1.jpg
a.
5 %
b.
10 %
c.
20 %
d.
40 %
 

 15. 


mc015-1.jpg
a.
a synchronous motor
c.
an induction motor
b.
an induction generator
d.
None of thses
 

 16. 

Match List I (different applications ) and List Ii (the motors for these applications) and find the correct answer using the codes given below the lists.
                List I                       LIst II
P.      Food mixer                    1. Permanent magnet DC motor
Q.      Cassettel tape recorder  2. A 1-mc016-1.jpg induction motor
R.      Domestic water pump    3. Universal motor
S.       Escalator                         4. A 3-mc016-2.jpg  induction motor
                                                  5.  DC series motor
                                               6. Stepper motor
Codes                        
       P    Q   R   S                                     
a.
3   6   4   5
b.
1   3   2   4
c.
3   1   2   4
d.
3   2   1   4
 

 17. 

For an induction motor, operating at a slip s, the ratio of gross power output to air gap power is qual to
a.
mc017-3.jpg
b.
(1-s)
c.
mc017-4.jpg
d.
mc017-5.jpg
 

 18. 

Damper winding is provided in a poly phase synchrous motor in order to
a.
damapen out the noise of the machine
b.
prevent hunting
c.
provide starting torque
d.
provide a cylindrical structure to reduce wind friction
 

 19. 

A synchronous motor operates at 0.8 pf lagging . If the field current of the motor is continuously increased
a.
the power factor decreases upto a certain value of field current and there after it increase 
b.
the armature current increases upto a certain value of field current and there after it decreases
c.
the power factor increases upto a certain value of field current and there after it decreases
d.
the armature current decreases upto a certain value of field current and there after it increases
 

 20. 

mc020-1.jpg
a.
mc020-2.jpg
b.
mc020-3.jpg
c.
mc020-4.jpg
d.
mc020-5.jpg
 

 21. 


mc021-1.jpg
a.
30mc021-3.jpg
b.
36mc021-4.jpg
c.
72mc021-5.jpg
d.
18mc021-6.jpg
 

 22. 

A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short-circuit and a terminal voltage of 2000 V on open-circuit .The magnitude of the internal voltage drop within the machine at a load current of 20  A is
a.
1 V
b.
10 V
c.
100 V
d.
1000 V
 

 23. 


mc023-1.jpg
a.
under-excited
b.
over-excited
c.
normally-excited
d.
disconnected from the common terminals
 

 24. 

‘Crawling ‘ in an induction motor is due to
a.
time harmonics in supply
b.
slip-ring rotor
c.
space harmonics produced by winding currents
d.
insufficient starting torque
 

 25. 

Match List I with List II and select the correct answer using the codes gives below the lists.
                   List I                      List II
P. Single-phase induction   1. Rotor resistance starting
        motor
Q .   3-phase      slip-ring      2. Not self starting
      Induction motor
R . 3-phase squirrel cage      3.Autotransformer starting
     induction motor

Codes
       P   Q   R
a.
2   1   3
b.
1   2   3
c.
2   3   1
d.
3  1   2
 

 26. 

As compared to DOL staring a cage induction motor with star - delta starting shall have
a.
more starting torque
c.
reduced starting current
b.
more starting time
d.
smoother acceleration
 

 27. 

Slip test is performed to determine
a.
slip
b.
direct axis reactance and quadrature axis
c.
positive sequence reactance and negative sequence reactance
d.
sub-transient reactance
 

 28. 

In a 3-phase induction motor ,torque and supply voltage are related as
a.
T mc028-3.jpg Vmc028-4.jpg
b.
T mc028-5.jpg V
c.
T mc028-6.jpg Vmc028-7.jpg
d.
mc028-8.jpg
 

 29. 

Maximum starting torque of a 3-phase induction motor is obtained when the rotor resistance is
a.
equal to the rotor reactance
b.
very small and rotor reactance is large
c.
double that of the rotor reactance
d.
1.5 times rotor reactance
 

 30. 

The speed of a 3-phase induction motor operating in its stable region
a.
decrease with increase in load torque
b.
increase with increase in load torque
c.
decreases with decrease in load torque
d.
remains constant
 

 31. 

The starting torque of a 3-phase induction motor can be increase by increased by increasing the
a.
rotor resistance
c.
stator resistance
b.
rotor reactance
d.
stator reactance
 

 32. 

A 3-phase slip-ring induction motor is wound for 4-poles on stator and 6-poles on rotor .When 3-phase balanced voltage source at 50 Hz is applied to the motor ,it will run at
a.
1500 rpm
b.
1000 rpm
c.
750 rpm
d.
Not run
 

 33. 

A 8-pole , DC genetator has simplex wave would armature contaning 32 coils of 6 turns each .Its flux per pole is 0.06 WB.The machine is runing at 250 rpm.The induced armature voltage is
a.
96 V
b.
192 V
c.
384 V
d.
768 V
 

 34. 

In relation to DC machine match List I (performance variable) with List II (proprotional to) and find the correct answer using the codes given below the lists.
                  List I                                    List II
P. Armature emf(E)         1. Flux (mc034-1.jpg), speed (mc034-2.jpg)
                                                       and armature current mc034-3.jpg

Q. Developed torque (T)   2. mc034-4.jpg and mc034-5.jpg
R. Developed power (p)    3. mc034-6.jpg and mc034-7.jpg
                                        4. mc034-8.jpg and mc034-9.jpg
                                        5.mc034-10.jpg only
Codes
      P    Q   R
a.
3   2   1
b.
2   5   4
c.
3   5   4
d.
2   3   1
 

 35. 


mc035-1.jpg
a.
3
b.
6
c.
4
d.
8
 

 36. 

A 400 V, 15 kW ,4- pole , 50 Hz , Y-connected induction motor has full silip of 4 % .The output torque of the machine at full load is
a.
1.66 N-m
b.
95.N-m
c.
99.47 N-m
d.
624.73 N-m
 

 37. 

A 500 MW 3-phase Y-connectedsynchronous generator has a rated voltage of 21.5 kV at 0.85 pf.
The line current when operating at full load rated conditions will be
a.
13.43 kA
b.
15.79 kA
c.
23.25 kA
d.
27.36 kA
 

 38. 


mc038-1.jpg
mc038-2.jpg
a.
0.995 lagging
b.
0.995 leading
c.
0.791 lagging
d.
0.848 leading
 

 39. 


mc039-1.jpg
a.
180 V mc039-7.jpg10 %
b.
180 V, +10 %
c.
100 V mc039-8.jpg 10 %
d.
None of these
 

 40. 

An electric motor with ‘constant output power ‘ will have a torque-speed characteristic in the form of a
a.
straight line through the origin
b.
straight line parallel to the speed axis
c.
circle about the origin
d.
rectangular hyperbola
 

 41. 

If a 230 V DC series motor is connected to a 230 V AC supply ,then the motor will
a.
vibrate violently
b.
run with less efficiency and more sparking
c.
not run
d.
None of the above
 

 42. 

If two 8-pole DC machines of identical armatures are wound ,one with lap winding and the other with wave winding,then
a.
wave wound machine will have more rated current more voltage
b.
lap wound machine will have more rated voltage and more current
c.
lap wound machine will have more rated voltage and less current
d.
wave would machine will have more rated voltage and less current
 

 43. 

If the speed of a DC motor increases with load torque ,then it is a
a.
series motor
c.
differenially compounded motor
b.
permanent magnet motor
d.
cumulatively compounded motor
 

 44. 

A DC shunt motor having unsaturated magnetic circuit runs at 1000 rpm with rated voltage .If the applied voltage is half of the rated voltage,the motor will run at
a.
200 rpm
b.
1000 rpm
c.
750 rpm
d.
500 rpm
 

 45. 

A 4-pole DC generator is running at 1500 rpm .The frequency of current in the armature winding will be
a.
25 Hz
b.
50 Hz
c.
100 Hz
d.
200 Hz
 

 46. 

A 440 V shunt motor has an armature resistance of 0.5 mc046-1.jpg and shunt field resistance of 650 mc046-2.jpg .If the no load current is 3 A , then current in the armature will be
a.
2.32 A
b.
3 A
c.
0.68 A
d.
880 A
 

Problem
 

 47. 


pr047-1.jpg
 

 48. 


pr048-1.jpg
 

 49. 


pr049-1.jpg
pr049-2.jpg
 

 50. 


pr050-1.jpg
 

 51. 


pr051-1.jpg
 

 52. 


pr052-1.jpg
 

 53. 


pr053-1.jpg
 

 54. 


pr054-1.jpg
 

 55. 


pr055-1.jpg
 

 56. 


pr056-1.jpg
 

 57. 


pr057-1.jpg
 

 58. 


pr058-1.jpg
 

 59. 


pr059-1.jpg
pr059-2.jpg
 

 60. 


pr060-1.jpg
 



 
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