Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. In case-the conditions for maximum power for a D.C. motor are established,theefficiency of the motor will be
a. 100%
b. around 90%
c. anywhere between 75% and 90%
d. less than 50%
Q. The ratio of starting torque to full-load torque is least in case of
a. series motors
b. shunt motors
c. compound motors
d. none of the above
Q. In D.C. motor which of the following can sustain the maximum temperature rise?
a. Slip rings
b. Commutator
c. Field winding
d. Armature winding
Q. Which of the following law/rule can he used to determine the direction of rotationofD.C. motor ?
a. Lenz's law
b. Faraday's law
c. Coloumb'slaw
d. Fleming's left-hand rule
Q. Which of the following load normally needs starting torque more than theratedtorque?
a. Blowers
b. Conveyors
c. Air compressors
d. Centrifugal pumps
Q. The starting resistance of a D.C. motor is generally
a. low
b. around 500 Q
c. 1000 Q
d. infinitely large
Q. The speed of a D.C. series motor is
a. proportional to the armature current
b. proportional to the square of the armature current
c. proportional to field current
d. inversely proportional to the armature current
Q. In a D.C. series motor, if the armature current is reduced by 50%, the torque of themotor will be equal to
a. 100% of the previous value
b. 50% of the previous value
c. 25% of the previous value
d. 10% of the previous value
Q. The current drawn by the armature of D.C. motor is directly proportional to
a. the torque required
b. the speed of the motor
c. the voltage across the terminals
d. none of the above
Q. The power mentioned on the name plate of an electric motor indicates
a. the power drawn in kW
b. the power drawn in kVA
c. the gross power
d. the output power available at the shaft
Q. Which D.C. motor has got maximum self loading property?
a. Series motor
b. Shunt motor
c. Cumulatively compounded 'motor
d. Differentially compounded motor
Q. Which D.C. motor will be suitable alongwith flywheel for intermittent light andheavyloads?
a. Series motor
b. Shunt motor
c. Cumulatively compounded motor
d. Differentially compounded motor
Q. If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens
a. nothing will happen to th£ motor
b. this will make armature to take heavy current, possibly burning it
c. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
d. motor will run at very slow speed
Q. D.C. series motors are used
a. where load is constant
b. where load changes frequently
c. where constant operating speed is needed
d. in none of the above situations.
Q. For the same H.P. rating and full load speed, following motor has poor starting torque
a. shunt
b. series
c. differentially compounded
d. cumulativelyc'ompounded