## electrician

### MCQ ON DC MOTOR PAGE - 3

1.
 Which type of motor would you choose for starting the transport vehicle A DC series motor B DC shunt motor C Separately excited DC motor D DC differentially compound motor Answer : A Explanation :
2.
 The back emf of a DC motor depends on the …… A Shape of the conductor B Field flux C Commutator segments D Brush material Answer : B Explanation :
3.
 The E.M.F induced in a.D.C motor while running  is lo…. A Assist the applied voltage B Oppose the applied voltage C Decrease he current D Increase the current Answer : B Explanation :
4.
 Calculate the back e.m.f (Eb) of a 220 V DC shunt motor. Armature resistance is 0.5 ohm and armature current is 40 A A 220 V B 210 V C 200 V D 190 V Answer : C Explanation :
5.
 A 220 V.D.C motor having an armature resistance 0.2 ohm and back and back emf 215 V, it draws a current of … A 15 amps B 20 amps C 25 amps D 50 amps Answer : C Explanation :
6.
 The armature resistance of a DC machine will be in the order of … A 750 to 1000 ohms B 500 to 750 ohms C 10 to 50  ohms D 0.1 to 1 ohm Answer : D Explanation :
7.
 The carbon brushes of DC machines become shorter by wearing out during the running time of the machine At what 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 : B Explanation :
8.
 The supply terminals of a.D.C shunt motor are reversed. What will be eh effect on the motor A It will run as a DC generator B It will run in the reverse direction C It will run in the same direction D It will burn out Answer : C Explanation :
9.
 What will be the consequences if the field circuit of a DC shunt motor is opened when the motor is running at no load conditions A The motor speed will be reduced drastically B The torque of the motor will be increases C The motor speed could become dangerously high D Field current will become zero and hence motor stops Answer : C Explanation :
10.
 To start a DC shunt motor the type of starter used is ….. A 2 point B 3 point C 4 point D Drum type Answer : B Explanation :
11.
 The connection of NVC in DC 3 point tarter is across DC supply in series with A Armature B Starting resistor C Overload relay D Shunt field Answer : D Explanation :
12.
 In a 3 point starter the No volt coil (NVC) is connected in series with … A Armature B Supply C starting resistor D Field Answer : D Explanation :
13.
 A.DC shunt motor connected through a 4 point starter starts normally when the starter handle is moved from OFF position to ON position. But the starter handle does not remain onion position. One of A Shunt filed B Protective resistor C Starting resistor D Overload coil Answer : B Explanation :
14.
 For which one of the following application D.C shunt motor is used A Electric trams or trains B Electric hoist and cranes C Drives with high starting torque D Machine tool drives Answer : D Explanation :
15.
 The full load current of a 10 KW, 250 V.D.C motor will be… A 10 amperes B 20 amperes C 30  amperes D 40 amperes Answer : D Explanation :
16.
 Which type of D.C motor is preferred for Elevators A DC shunt motor B DC series motor C Cumulatively compounded DC motor D Differentially compounded DC motor Answer : C Explanation :