Top 150+ Solved Electrical Drives and Controls (EDC) MCQ Questions Answer
Q. With a P-pole DC machine with armature current Ia, the current per brush arm for a lap connected windings is?
a. ia/p
b. ia/2p
c. 2ia/p
d. ia/4p
Q. While doing regular checks on the dc machine with the lap connected winding, it is reported to have ammeter fluctuations, this can be due to
a. different air gaps under poles
b. variable reluctances in the core
c. irregular design deformations
d. all of the mentioned
Q. A 6-pole lap wound DC generator has a developed power of P watts and brush voltage of E volts. Three adjacent brushes of the machine had been found worn out and got open circuited. If the machine is operated with the remaining brushes, voltage and power that could be obtained from the machine are
a. e, p
b. e, 2p/3
c. e/p, 2p/3
d. e, p/3
Q. 1 = 0.0917.
a. reduce armature voltage
b. increase armature voltage
c. increase field current
d. decrease field current
Q. Ward Leonard method is
a. armature control method
b. field control method
c. combination of armature control method and field control method
d. totally different from armature and field control method
Q. Reducing the field current will give us
a. constant torque and variable power speed control
b. constant torque speed control
c. variable power speed control
d. constant power speed control
Q. Speed-power characteristic for Ward Leonard speed control method
a. will start from origin
b. will start from some positive value on power axis
c. will start from some positive value on speed axis
d. depends on other parameters
Q. Efficiency of Ward Leonard method is
a. higher than rheostatic control method but lower than shunted field control method
b. lower than rheostatic control method
c. higher than rheostatic control method and shunted field control method
d. depends on load
Q. 1 SPEED CONTROL OF THREE PHASE INDUCTION MOTOR
a. slip frequency
b. supply frequency
c. the frequency corresponding to rotor speed
d. zero
Q. Calculate the moment of inertia of the disc having a mass of 54 kg and diameter of 91 cm.
a. 5.512 kgm2
b. 5.589 kgm2
c. 5.487 kgm2
d. 5.018 kgm2
Q. Calculate the moment of inertia of the thin spherical shell having a mass of 73 kg and diameter of 36 cm.
a. 1.56 kgm2
b. 1.47 kgm2
c. 1.38 kgm2
d. 1.48 kgm2
Q. A 50 Hz, 4poles, a single phase induction motor is rotating in the clockwise direction at a speed of 1425 rpm. The slip of motor in the direction of rotation & opposite direction of the motor will be respectively.
a. 0.05, 0.95
b. 0.04, 1.96
c. 0.05, 1.95
d. 0.05, 0.02
Q. The frame of an induction motor is made of
a. aluminum
b. silicon steel
c. cast iron
d. stainless steel
Q. In an induction motor, when the number of stator slots is equal to an integral number of rotor slots
a. there may be a discontinuity in torque slip characteristics
b. a high starting torque will be available
c. the maximum torque will be high
d. the machine may fail to start