Series - D.C Motor - MCQs with Answers

Series - D.C Motor - MCQs with Answers

Q1. For d.c. series motor, if I_a is the armature current then the torque developed is

a. α I_a
b. α I_a²
c. α (1 / I_a²)
d. α (1 / I_a)

View Answer / Hide Answer

Q2. Neglecting saturation, if the current drawn from by a d.c. series motor is increased from 15 A to 18 A, then the increase in the torque expressed as percentage of initial torque will be

a. 22 %
b. 33%
c. 44%
d. 56.78%

View Answer / Hide Answer

Q3. A 4 pole 240 V, d.c. series motor has a wave wound armature with 180 conductors. The armature resistance and the field winding resistance are 0.10 ohm and 0.2 ohm respectively. If the motor is drawing 40 A current at 0.015 Wb flux per pole, then the speed under this condition is

a. 2533.3 rpm
b. 2644.4 rpm
c. 2756.9 rpm
d. 2987.6 rpm

View Answer / Hide Answer

Q4. The starting torque developed in the d.c. series motor and in d.c. shunt motor is

a. High, low
b. High, moderate
c. Moderate , low
d. Moderate, high

View Answer / Hide Answer

Q5. The speed of a d.c. series motor is

a. Directly proportional to the both armature current and torque developed
b. Inversely proportional to the armature current and square root of torque developed
c. Directly proportional to the square of the armature current and square root of torque developed
d. Inversely proportional to the square of the armature current and square of torque developed

View Answer / Hide Answer

Q6. The speed armature current characteristics of a d.c. series motor is

a. Rectangular hyperbola
b. Linear
c. Parabolic
d. Parabolic till saturation and then linear

View Answer / Hide Answer

Q7. If a d.c. series motor is started on very light load or on no load then

a. It will run at dangerously high speed which may damage the motor mechanically
b. It will run at very low speed
c. Load does not effect the speed of d.c. series motor
d. None of these

View Answer / Hide Answer

Q8. Can a d.c. series motor be used for applications in belt drives?

a. Yes
b. No

View Answer / Hide Answer

Q9. D.C. series motors are used in electric traction. What happens to the speed and current of d.c motor if there is sudden slight drop in the mains voltage?

a. Speed decreases and current also decreases
b. Speed decreases and current increases
c. Speed increases and current decreases
d. Speed decreases and current remains same

View Answer / Hide Answer