Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. Which of the following motor has the poorest speed regulation ?
a. Shunt motor
b. Series motor
c. Differential compound motor
d. Cumulative compound motor
Q. Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make useof
a. D.C. series motor
b. D.C. shunt motor
c. induction motor
d. all of above motors
Q. As -the load is increased the speed of D.C. shunt motor will
a. reduce slightly
b. increase slightly
c. increase proportionately
d. remains unchanged
Q. The armature torque of the D.C. shunt motor is proportional to
a. field flux only
b. armature current only
c. both (a) and (b)
d. none of the above
Q. Which of the following method of speed control of D.C. machine will offer minimumefficiency ?
a. Voltage control method
b. Field control method
c. Armature control method
d. All above methods
Q. Usually wide and sensitive speed control is desired in case of
a. centrifugal pumps
b. elevators
c. steel rolling mills
d. colliery winders
Q. The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load.The speed regulation of the motor is
a. 2.36%
b. 4.76%
c. 6.77%
d. 8.84%
Q. The armature voltage control of D.C. motor provides
a. constant torque drive
b. constant voltage drive
c. constant current drive
d. none of the above
Q. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent aheavy current from flowing though the armature circuit
a. a resistance is connected in series with armature
b. a resistance is connected parallel to the armature
c. armature is temporarily open circuited
d. a high value resistor is connected across the fieldwinding
Q. The speed of a D.C. shunt motor can be increased by
a. increasing the resistance in armature circuit
b. increasing the resistance in field circuit
c. reducing the resistance in the field circuit
d. reducing the resistance in the armature circuit
Q. If I2 be the armature current, then speed of a D.C. shunt motor is
a. independent of Ia
b. proportional to la
c. varies as (Ia)
d. varies as la
Q. In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developedby the motor will
a. remain unchanged
b. reduce to one-fourth value
c. increase four folds
d. be doubled
Q. At the instant of starting when a D.C. motor is put on supply, it behaveslike
a. a highly resistive circuit
b. a low resistance circuit
c. a capacitive circuit
d. none of the above
Q. The speed of a D.C. motor can be varied by varying
a. field current
b. applied voltage
c. resistance in series with armature
d. any of the above
Q. Which one of the following is not necessarily the advantage of D.C. motors over A.C.motors ?
a. Low cost
b. Wide speed range
c. Stability
d. High starting torque.