141) Which DC motor will be preferred for machine tools?

  1. Series motor
  2. Shunt motor
  3. Cumulative compound motor
  4. Differential compound motor
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

142) Differentially compound DC motors can find applications requiring ___________?

  1. High starting torque
  2. Low starting torque
  3. Variable speed
  4. Frequent on-off cycles
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

143) Which DC motor is preferred for elevators ?

  1. Shunt motor
  2. Series motor
  3. Differential compound motor
  4. Cumulative compound motor
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

144) If the field of a DC shunt motor gets opened while motor is running _____________?

  1. The speed of motor will be reduced 
  2. The armature current will reduce
  3. The motor will attain dangerously high speed
  4. he motor will continue to run constant speed
ANSWER
Answer: ( 3 )
EXPLANATION
No answer description required for this question.

145) Starters are used with DC motors because______________?

  1. These motors have high starting torque
  2. These motors are not self-starting
  3. Back e.m.f. of these motors is zero initially
  4. To restrict armature current as there is no back e.m.f. while starting
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

146) In DC shunt motors as load is reduced__________________?

  1. The speed will increase abruptly
  2. The speed will increase in proportion to reduction in load
  3. The speed will remain almost constant
  4. The speed will reduce
ANSWER
Answer: ( 3 )
EXPLANATION
No answer description required for this question.

147) A DC series motor is that which______________?

  1. Has its field winding consisting of thick wire and less turns
  2. Has a poor torque
  3. Can be started easily without load
  4. Has almost constant speed
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

148) For starting a DC motor a starter is required because___________?

  1. It limits the speed of the motor
  2. It limits the starting current to a safe value
  3. It starts the motor
  4. None of the above
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

149) The type of DC motor used for shears and punches is_____________?

  1. Shunt motor
  2. Series motor
  3. Differential compound DC motor
  4. Cumulative compound DC motor
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

150) If a DC motor is connected across the AC supply it will _______________?

  1. Run at normal speed
  2. Not run
  3. Run at lower speed
  4. Burn due to heat produced in the field winding by eddy currents
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

151) To get the speed of DC motor below the normal without wastage of electrical energy is used?

  1. Ward Leonard control
  2. Rheostatic control
  3. Any of the above method
  4. None of the above method
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

152) When two DC series motors are connected in parallel, the resultant speed is____________?

  1. More than the normal speed
  2. Less than the normal speed
  3. Normal speed
  4. Zero
ANSWER
Answer: ( 3 )
EXPLANATION
No answer description required for this question.

153) The speed of a DC shunt motor more than its full-load speed can be obtained by_____________?

  1. Decreasing the field current
  2. Increasing the field current
  3. Decreasing the armature current
  4. Increasing the armature current
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

154) In a DC shunt motor, speed is______________?

  1. Independent of armature current
  2. Directly proportional to the armature current
  3. Proportional to the square of the current
  4. Inversely proportional to the armature current
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

155) A direct on line starter is used: for starting motors___________?

  1. Up to 5 H.P
  2. Up to 10 H.P
  3. Up to 15 H.P
  4. Up to 20 H.P
ANSWER
Answer: ( 1 )
EXPLANATION
No answer description required for this question.

156) What will happen if the back e.m.f. of a DC motor vanishes suddenly?

  1. The motor will stop
  2. The motor will continue to run
  3. The armature may burn
  4. The motor will run noisy
ANSWER
Answer: ( 3 )
EXPLANATION
No answer description required for this question.

157) In case of DC shunt motors the speed is dependent on back e.m.f. only because____________?

  1. Back e.m.f. is equal to armature drop
  2. Armature drop is negligible
  3. Flux is proportional to armature current
  4. Flux is practically constant in DC shunt motors
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

158) In a DC shunt motor, under the conditions of maximum power, the current in the armature will be_____________?

  1. Almost negligible
  2. Rated full-load current
  3. Less than full-load current
  4. More than full-load current
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

159) In DC machines fractional pitch winding is used __________?

  1. To improve cooling
  2. To reduce copper losses
  3. To increase the generated e.m.f.
  4. To reduce the sparking
ANSWER
Answer: ( 4 )
EXPLANATION
No answer description required for this question.

160) A three point starter is considered suitable for______________?

  1. Shunt motors
  2. Shunt as well as compound motors
  3. Shunt, compound and series motors
  4. All DC motors
ANSWER
Answer: ( 2 )
EXPLANATION
No answer description required for this question.

Pin It on Pinterest