130 TOP D.C.MOTOR Questions and Answers pdf

11. In D.C. shunt motors as load is reduced
(a) the speed will increase abruptly
(b) the speed will increase in proportion to reduction in load
(c) the speed will remain almost/constant
(d) the speed will reduce
Ans: c

12. A D.C. series motor is that which
(a) has its field winding consisting of thick wire and less turns
(b) has a poor torque
(c) can be started easily without load
(d) has almost constant speed
Ans: a

13. For starting a D.C. motor a starter is required because
(a) it limits the speed of the motor
(b) it limits the starting current to a safe value
(c) it starts the motor
(d) none of the above
Ans: b

14. The type of D.C. motor used for shears and punches is
(a) shunt motor
(b) series motor
(c) differential compoutid D.C. motor
(d) cumulative compound D.C. motor
Ans: d

15. If a D.C. motor is connected across the A.C. supply it will
(a) run at normal speed
(b) not run
(c) run at lower speed
(d) burn due to heat produced in the field winding by .eddy currents
Ans: d

16. To get the speed of D.C, motor below the normal without wastage of electrical energy is used.
(a) Ward Leonard control
(b) rheostatic control
(c) any of the above method
(d) none of the above method
Ans: a

17. When two D.C. series motors are connected in parallel, the resultant speed is
(a) more than the normal speed
(b) loss than the normal speed
(c) normal speed
(d) zero
Ans: c

18. The speed of a D.C. shunt motor more than its full-load speed can be obtained by
(a) decreasing the field current
(b) increasing the field current
(c) decreasing the armature current
(d) increasing the armature current
Ans: a

19. In a D.C. shunt motor, speed is
(a) independent of armature current
(b) directly proportional to the armature current
(c) proportional to the square of the current
(d) inversely proportional to the armature current
Ans: a

20. A direct on line starter is used: for starting motors
(a) up to 5 H.P.
(b) up to 10 H.P.
(c) up to 15 H.P.
(d) up to 20 H.P.
Ans: a



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