By Surendra | June 10, 2020 0 Comment 0% 4 Created by Surendra DC Generators Quiz in English Set 1 All Important Question Answers for Electrician Related Exams 1 / 25 In case of D.C. machines mechanical losses are primary function of current speed voltage none of above 2 / 25 Which of the following could be lamina-proximately the thickness of lamination’s of a D.C. machine ? 0.005 mm 5 mm 0.5 mm 0.05 mm 3 / 25 In a commutator copper is harder than mica mica and copper are equally hard mica is harder than copper none of the above 4 / 25 Copper brushes in D.C. machine are used where low voltage and high currents are involved where high voltage and small cur-rents are involved in none of the above cases in both of the above cases 5 / 25 The bearings used to support the rotor shafts are generally bush bearings needle bearings ball bearings magnetic bearmgs 6 / 25 The e.m.f. generated in a D.C. generator is directly proportional to number of poles all of the above speed of armature flux/pole 7 / 25 While applying Fleming’s right-hand rule to And the direction of induced e.m.f. the thumb points towards direction of motion of the conductor if forefinger points in the direction of generated e.m.f. direction of motion of conductor if forefinger points along the lines of flux direction of induced e.m.f. direction of flux 8 / 25 In D.C. generators the cause of rapid brush wear may be severe sparking rough commutator surface imperfect contact any of the above 9 / 25 For a D.C. generator when the number of poles and the number of armature conductors is fixed then which winding will give the higher e.m.f. ? Lap winding Either of and above Depends on other features of design Wave winding 10 / 25 Fleming’s right-hand rule regarding direction of induced e.m.f. correlates magnetic field strength induced voltage and current magnetic flux direction of current flow and resultant force magnetic flux direction of motion and the direction of e.m.f. induced magnetic flux direction of force and direction of motion of conductor 11 / 25 In lap winding the number of brushes is always double the number of poles half the number of poles same as the number of poles two 12 / 25 Lamination’s of core are generally made of case iron stainless steel silicon steel carbon 13 / 25 According to Fleming’s right-hand rule for finding the direction of induced e.m.f. when middle finger points in the direction of induced e.m.f. forefinger will point in the direction of either of the above motion of conductor none of the above lines of force 14 / 25 In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis when the generator runs on overload the generator runs on designed speed there is no load on|he generator the generator runs on full load 15 / 25 The commutator segments are connected to the armature conductors by means of insulation pads copper lugs resistance wires brazing 16 / 25 Permeance is the reciprocal of ampere-turns reluctance resistance flux density 17 / 25 Iron losses in a D.C. machine are independent of variations in voltage speed and voltage load speed 18 / 25 The resistance of armature winding depends on all of the above cross-sectional area of the conductor length of conductor number of conductors 19 / 25 In D.C. generators the polarity of the interpoles is the same as that of the immediately preceding pole is opposite to that of the main pole ahead is neutral as these poles do not play part in generating e.m.f. is the same as that of the main pole ahead 20 / 25 In a four-pole D.C. machine all the four poles are north poles two north poles follow two south poles all the four poles are south poles alternate poles are north and south 21 / 25 The field coils of D.C. generator are usually made of carbon copper mica cast iron 22 / 25 In D.C. generators the pole shoes are fastened to the pole core by rivets brazing counter sunk screws welding 23 / 25 In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2 r.p.m. is more than 300 r.p.m. is less than 300 number of poles is 4 24 / 25 A separately excited generator as compared to a self-excited generator has exciting current independent of load current is more stable is amenable to better voltage control has all above features 25 / 25 The armature of D.C. generator is laminated to reduce eddy current loss provide the bulk reduce the bulk insulate the core कृपया सही सूचना भरें ताकि सर्टिफिकेट ईमेल पर भेजा जा सकें। NameEmailPhone NumberDistrictSchool/Coaching Name Your score is LinkedIn Facebook VKontakte 0% Restart quiz आपको यह क्विज अच्छी लगी तो 5 स्टार रेटिंग जरुर दें । Send feedback
