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Monday, 14 August 2017

Teachanical test 14 / 08 2017

1.       



1 .      1. At starting , the current through the starting winding of single phase induction motor
A ) lags V by 90 degree
B ) leads V by 90 degree
C ) is nearly in phase with V
D ) leads V by 75 degree

correct answer C ) is nearly in phase with V
                                                                                         ssc je 2014

2 .  If the excitation of an alternator operating in parallel  with other alternator is increased above the normal value of excitation its
A )power factor becomes more lagging
B ) power factor becomes more leading
C ) output current decreases
D ) output KW decreases

correct answer A )power factor becomes more lagging
                                                                                                   ssc je 2014
3 . In an alternator , the effect of armature reaction is minimum at power factor of
A ) 0.5 lagging
B ) 0.866 lagging
C ) 0.866 leading
D ) unity

correct answer D ) unity
                                                                             ssc je 2014
4 . Turbo alternators have rotors of
A )small diameter and long axial length
B ) large diameter and long axial length
C )large diameter and small axial length
D ) small diameter and small axial length

correct answer A )small diameter and long axial length
                                                                                              ssc je 2014
5 .Which of the following equipments is used to limit short – circuit current level in a substation ?
A ) isolator
B ) lighting switch
C ) coupling capacitor
D ) series reactor

 correct answer D ) series reactor
                                                                                                  ssc je 2014
6 . Power distribution by cable is generally adopted for line length
A ) less than 10 Km
B ) above 10 Km
C ) less than 50 Km
D ) above 50 Km

coeerct answer A ) less than 10 Km
                                                                                 ssc je 2014

7 . The leakage resistance of a 50 Km long cable is 1 Megaohms. For a 100 Km long cable it will be
A ) 0.5 Megaohms
B ) 2 Megaohms
C )0.66 Megaohms
D ) none of these

correct answer A ) 0.5 Megaohms
                                                                                    ssc je 2014

8. If voltage is increased by ‘ n ‘ times , the size of the conductor would
A ) increase by n times
B ) reduce by 1/n
C ) increase by n2
D ) reduce by 1/n2

correct answer D ) reduce by 1/n2
                                                                                      ssc je 2014

9. The maximum demand of a consumer is 2 Kw and his daily energy consumption is 24 units . his load factor is ……………. % .
A ) 24
B ) 41.6
C ) 50
D ) 80

correct answer C ) 50
                                                                                      ssc je 2014

10 . A synchronous motor can be used as synchronous condenser when it is
A ) over excited
B ) over loaded
C ) under excited
D )under loaded

correct answer A ) over excited
                                                                                        ssc je 2014

1 .      1. At starting , the current through the starting winding of single phase induction motor
A ) lags V by 90 degree
B ) leads V by 90 degree
C ) is nearly in phase with V
D ) leads V by 75 degree

correct answer C ) is nearly in phase with V
                                                                                         ssc je 2014

2 .  If the excitation of an alternator operating in parallel  with other alternator is increased above the normal value of excitation its
A )power factor becomes more lagging
B ) power factor becomes more leading
C ) output current decreases
D ) output KW decreases

correct answer A )power factor becomes more lagging
                                                                                                   ssc je 2014
3 . In an alternator , the effect of armature reaction is minimum at power factor of
A ) 0.5 lagging
B ) 0.866 lagging
C ) 0.866 leading
D ) unity

correct answer D ) unity
                                                                             ssc je 2014
4 . Turbo alternators have rotors of
A )small diameter and long axial length
B ) large diameter and long axial length
C )large diameter and small axial length
D ) small diameter and small axial length

correct answer A )small diameter and long axial length
                                                                                              ssc je 2014
5 .Which of the following equipments is used to limit short – circuit current level in a substation ?
A ) isolator
B ) lighting switch
C ) coupling capacitor
D ) series reactor

 correct answer D ) series reactor
                                                                                                  ssc je 2014

6 . Power distribution by cable is generally adopted for line length
A ) less than 10 Km
B ) above 10 Km
C ) less than 50 Km
D ) above 50 Km

coeerct answer A ) less than 10 Km
                                                                                 ssc je 2014

7 . The leakage resistance of a 50 Km long cable is 1 Megaohms. For a 100 Km long cable it will be
A ) 0.5 Megaohms
B ) 2 Megaohms
C )0.66 Megaohms
D ) none of these

correct answer A ) 0.5 Megaohms
                                                                                    ssc je 2014

8. If voltage is increased by ‘ n ‘ times , the size of the conductor would
A ) increase by n times
B ) reduce by 1/n
C ) increase by n2
D ) reduce by 1/n2

correct answer D ) reduce by 1/n2
                                                                                      ssc je 2014

9. The maximum demand of a consumer is 2 Kw and his daily energy consumption is 24 units . his load factor is ……………. % .
A ) 24
B ) 41.6
C ) 50
D ) 80

correct answer C ) 50
                                                                                      ssc je 2014

10 . A synchronous motor can be used as synchronous condenser when it is
A ) over excited
B ) over loaded
C ) under excited

D )under loaded

correct answer A ) over excited
                                                                                        ssc je 2014


        11  .The material to be used in the manufacture of a standard  resistor should be of
A ) low resistivity
 B ) high resistivity and low temperature coefficient
C ) high temperature coefficient
D ) low resistivity and high temperature coefficient

2.     12 .  In a 3-phase induction motor crawling happen at
A ) any speed
B ) no load speed
C ) odd multiples of fundamental
D ) even multiples of fundamental

3.      1 3 .A 4 pole , 3- phase induction motor run at 1440 rpm on a 50 Hz supply. Find the slip speed
A ) 2940 rpm
B ) 1500 rpm
C ) 1440 rpm
D ) 60 rpm

4.         1 4. .Low voltage windings are placed nearer to the core in the case of concentric windings because
A )it reduces hysteresis loss
B  ) it reduces eddy current loss
C ) it reduces insulation requirement
D ) it reduces leakage fluxes


5.       1 5.If k is the phase to phase voltage ratio , then the line to line voltage ratio in a 3 -phase star-delta transformer is 
              A ) k   
              B ) k /√3
              C ) √3k
              D ) √3 /k
        1 6. In an autotransformer of voltage ratio V1/V2 , V1>V2 , the fraction of power transferred inductively is proportional to
           A ) V1/ (V1+V2)
           B  ) V2/V1
           C ) (V1 - V2 )/ (V1 + V2 )
           D ) (V1- V2)/V1
        
      1 7. Stepped core is used in transformers in order to reduce 
       A ) volume of iron 
       B ) volume of copper 
       C ) iron loss 
       D ) reluctance of core
    
       1 8.  Communication condition at full load for large  DC machine can be efficiency checked by the 
       A ) brake test
       B ) Swinburne 's test
       C ) Hopkinson's test
       D ) filed test


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