## electrician

### MCQ ON DC GENERATOR PAGE - 2

1.
 The brushes are alwys placed along A MNA (magnetic neutral axis B GNA (geometic neutral axis) C Perpendicular to MNA D Prependicular to GNA Answer : A Explanation :
2.
 The function of compensating winding is to neutralize A Reactance voltage generated as a consequence of commutation B Cross magnetizing the effect of armature reaction C Demagnetizing effect of armature reaction D All the above. Answer : C Explanation :
3.
 In any d.c. generator, the emf generated in the armature is maximum when: A Rate of change of flux is minimum B Rate of change of flux is maximum C Flux linked with conductors a maximum D Flux linked with conductors is minimum Answer : B Explanation :
4.
 The method which can be used to improve commutation process is A To increase the resistance of brushes B To reduced the no of turns in the armature coil so as to reduce the no. of commutator segments C To neutralize the reactance voltage by producing a reversing emf in the short circuited coil unde D All the above Answer : D Explanation :
5.
 The function of interpoles is A To neutralize the reactance voltage to help commutation process B To neutralize the cross magnetizing effect of armature reaction C To reduce sparking at the commutator D All the above Answer : D Explanation :
6.
 Shunt generators are used where the main requirement is a constant. A Voltage and current B Current C Voltage over a wide load range D Voltage over a narrow load range Answer : D Explanation :
7.
 Interpoles are normally connected in A Parallel with the field windings B Series with the filed windings C Parallel with the load D Series with the load Answer : B Explanation :
8.
 In d.c. generator, which loss varies with the load A Copper loss B Eddy current loss C Hysteresis loss D Windage loss Answer : A Explanation :
9.
 In d.c. generators,  lap winding is used for ; A Low voltage, low current B High voltage , high current C Low voltage, high current D High voltage, low current Answer : C Explanation :
10.
 D.C generator preferred for charging automobiles batteries is: A Shunt generator B Series generator C Long shunt compound generator D Short shunt compound generator Answer : A Explanation :
11.
 The over all efficiency of a d.c. generator lies in the range of : A 60-80% B 75-85% C 80-90% D 85-95% Answer : D Explanation :
12.
 The function of an equalizer ring is A To avoid unequal distribution of current at the brushes . B To help in reducing sparking C Both the above D None of the above Answer : C Explanation :
13.
 The carbon brushes of DC machines become shorter by wearing out during the running time of the machine. At which length do you have to change the brushes A ½ of the original length B 1/3 of the original length C 3/4 of the original length D 2/3 of the original length Answer : D Explanation :
14.
 A2 KW, 200 V,DC generator will supply a load current of A 2 amps B 4 amps C 10 amps D 20 amps Answer : C Explanation :
15.
 The essential condition for stable parallel operating of two D.C generators having  similar characterstics is that they should have A Same kilowatt output ratings B Drooping voltage characteristics C Same percentage regulation D Same no load and full load speed Answer : B Explanation :
16.
 D.C. generators are connected to or disconnected from the busbar only under the floating condition. This is done to avoid A Burning of switch contact B Sudden loading of the prime mover C Mechanical jerk to the shaft D All of the above Answer : D Explanation :
17.
 For parallel operation the D.C generators normally preferred are A Shunt and over compound B Series C Shunt and under compound D Over compound Answer : C Explanation :
18.
 Equalizer bar is necessary for parallel operating of DC A Series and over compound generator B Under compound generator C Shunt and series generator D Over compound generator Answer : A Explanation :
19.
 DC shunt generators are most suited for stable parallel operation because of their votlge characteristics A Identical B Dropping C Linear D Rising Answer : B Explanation :
20.
 Two parallel shunt generators will divide the total load equality in proportion to their kilowatt output ratings only when they have the same A a) Rated voltage B Voltage regulation C Internal Ia, Ra drops D Both A and B Answer : D Explanation :