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 Iron losses in a D.C. machine are independent of variations in speed and voltage load speed voltage 2 / 25 The e.m.f. generated in a D.C. generator is directly proportional to speed of armature all of the above number of poles flux/pole 3 / 25 The field coils of D.C. generator are usually made of cast iron mica carbon copper 4 / 25 A separately excited generator as compared to a self-excited generator has all above features is more stable has exciting current independent of load current is amenable to better voltage control 5 / 25 In D.C. generators the cause of rapid brush wear may be imperfect contact rough commutator surface any of the above severe sparking 6 / 25 In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 4 r.p.m. is more than 300 number of poles is 2 r.p.m. is less than 300 7 / 25 In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis when there is no load on|he generator the generator runs on designed speed the generator runs on full load the generator runs on overload 8 / 25 Fleming’s right-hand rule regarding direction of induced e.m.f. correlates magnetic flux direction of current flow and resultant force magnetic field strength induced voltage and current magnetic flux direction of motion and the direction of e.m.f. induced magnetic flux direction of force and direction of motion of conductor 9 / 25 In D.C. generators the pole shoes are fastened to the pole core by welding counter sunk screws brazing rivets 10 / 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 motion of conductor either of the above none of the above lines of force 11 / 25 Copper brushes in D.C. machine are used in none of the above cases where high voltage and small cur-rents are involved in both of the above cases where low voltage and high currents are involved 12 / 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. ? Either of and above Depends on other features of design Wave winding Lap winding 13 / 25 In lap winding the number of brushes is always same as the number of poles half the number of poles double the number of poles two 14 / 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 flux direction of motion of conductor if forefinger points along the lines of flux direction of induced e.m.f. 15 / 25 The commutator segments are connected to the armature conductors by means of copper lugs resistance wires brazing insulation pads 16 / 25 Permeance is the reciprocal of resistance ampere-turns reluctance flux density 17 / 25 Lamination’s of core are generally made of stainless steel carbon silicon steel case iron 18 / 25 The bearings used to support the rotor shafts are generally magnetic bearmgs bush bearings needle bearings ball bearings 19 / 25 The resistance of armature winding depends on all of the above cross-sectional area of the conductor number of conductors length of conductor 20 / 25 Which of the following could be lamina-proximately the thickness of lamination’s of a D.C. machine ? 0.5 mm 0.05 mm 0.005 mm 5 mm 21 / 25 The armature of D.C. generator is laminated to reduce the bulk insulate the core provide the bulk reduce eddy current loss 22 / 25 In D.C. generators the polarity of the interpoles is the same as that of the main pole ahead 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. 23 / 25 In a commutator mica is harder than copper copper is harder than mica mica and copper are equally hard none of the above 24 / 25 In a four-pole D.C. machine all the four poles are south poles two north poles follow two south poles alternate poles are north and south all the four poles are north poles 25 / 25 In case of D.C. machines mechanical losses are primary function of none of above voltage speed current 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
