DC Motor solved MCQs

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DC MOTOR1. No-load speed of which of the following motor will be highest ? DC MOTOR1. No-load speed of which of the following motor will be highest ? Shunt motor Series motor Cumulative compound motor Differentiate compound motor discuss The answer is: B. Series motor
The direction of rotation of a D.C. series motor can be changed by The direction of rotation of a D.C. series motor can be changed by interchanging supply terminals interchanging field terminals either of (a) and (b) above None of the above discuss The answer is: B. interchanging field terminals
Which of the following application requires high starting torque ? Which of the following application requires high starting torque ? Lathe machine Centrifugal pump Locomotive Air blower discuss The answer is: C. Locomotive
If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ? If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ? Series motor Shunt motor Differentially compound motor Cumulative compound motor discuss The answer is: A. Series motor
Which D.C. motor will be preferred for machine tools ? Which D.C. motor will be preferred for machine tools ? Series motor Shunt motor Cumulative compound motor Differential compound motor discuss The answer is: B. Shunt motor
Differentially compound D.C. motors can find applications requiring Differentially compound D.C. motors can find applications requiring high starting torque low starting torque variable speed frequent on-off cycles discuss The answer is: B. low starting torque
Which D.C. motor is preferred for elevators ? Which D.C. motor is preferred for elevators ? Shunt motor Series motor Differential compound motor Cumulative compound motor discuss The answer is: D. Cumulative compound motor
According to Fleming's left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of According to Fleming's left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of current in the conductor aovtaat of conductor resultant force on conductor none of the above none of the above discuss The answer is: A. current in the conductor aovtaat of conductor
If the field of a D.C. shunt motor gets opened while motor is running If the field of a D.C. shunt motor gets opened while motor is running the speed of motor will be reduced % the armature current will reduce the motor will attain dangerously high speed 1 the motor will continue to nuvat constant speed discuss The answer is: C. the motor will attain dangerously high speed 1
Starters are used with D.C. motors because Starters are used with D.C. motors because these motors have high starting torque these motors are not self-starting back e.m.f. of these motors is zero initially to restrict armature current as there is no back e.m.f. while starting discuss The answer is: D. to restrict armature current as there is no back e.m.f. while starting
In D.C. shunt motors as load is reduced In D.C. shunt motors as load is reduced the speed will increase abruptly the speed will increase in proportion to reduction in load the speed will remain almost/constant the speed will reduce discuss The answer is: C. the speed will remain almost/constant
A D.C. series motor is that which A D.C. series motor is that which has its field winding consisting of thick wire and less turns has a poor torque can be started easily without load has almost constant speed discuss The answer is: A. has its field winding consisting of thick wire and less turns
For starting a D.C. motor a starter is required because For starting a D.C. motor a starter is required because it limits the speed of the motor it limits the starting current to a safe value it starts the motor none of the above discuss The answer is: B. it limits the starting current to a safe value
The type of D.C. motor used for shears and punches is The type of D.C. motor used for shears and punches is shunt motor eries motor differential compoutid D.C. motor cumulative compound D.C. motor discuss The answer is: D. cumulative compound D.C. motor
If a D.C. motor is connected across the A.C. supply it will If a D.C. motor is connected across the A.C. supply it will run at normal speed not run run at lower speed burn due to heat produced in the field winding by .eddy currents discuss The answer is: D. burn due to heat produced in the field winding by .eddy currents
To get the speed of D.C, motor below the normal without wastage of electrical energyis used To get the speed of D.C, motor below the normal without wastage of electrical energyis used. Ward Leonard control rheostatic control any of the above method none of the above method discuss The answer is: A. Ward Leonard control
When two D.C. series motors are connected in parallel, the resultant speed is When two D.C. series motors are connected in parallel, the resultant speed isa more than the normal speed loss than the normal speed normal speed zero discuss The answer is: C. normal speed
The speed of a D.C. shunt motor more than its full-load speed can be obtained by The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current increasing the field current decreasing the armature current increasing the armature current discuss The answer is: A. decreasing the field current
In a D.C. shunt motor, speed is In a D.C. shunt motor, speed is independent of armature current directly proportional to the armature current proportional to the square of the current inversely proportional to the armature current discuss The answer is: A. independent of armature current
A direct on line starter is used: for starting motors A direct on line starter is used: for starting motors iip to 5 H.P. up to 10 H.P. up to 15 H.P. up to 20 H.P. discuss The answer is: A. iip to 5 H.P.

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