300 Important DC Motor MCQ Questions & Answers with Explanation | PDF Free Download
1.A dc shunt motor is driving a constant torque load with normal excitation. If the filed current is halved then the motor will run at
- ARated speed
- BHalf of rated speed
- CDouble of rated speed
- DSlightly less than double the rated speed
2.A dc shunt motor is driving a mechanical load at rated voltage with normal excitation. If the load torque is increased to double of the normal one, the speed of the motor will
- ABecome half
- BBecome double
- CIncrease slightly
- DFall slightly
3.When a dc cumulative compound wound motor is loaded
- ATorque increases and speed decreases
- BTorque decreases and speed increases
- CBoth speed and torque increase
- DBoth speed ad torque decrease
4.A belt driven cumulative compounded dc generator is delivering power to the dc mains. If the belt snaps then the machine will run as a
- ACumulative compounded motor in the same direction
- BDifferentially compounded motor in the same direction
- CCumulative compounded motor in the opposite direction
- DDifferentially compounded motor in the opposite direction
5.Flywheel is employed with a dc compound motor to reduce peak demand. The compound motor should be
- ALevel compound
- BDifferential compound
- CCumulative compound
- DNone of these
6.In a differentially compounded dc motor, if the shunt filed gets suddenly opened the motor will
- ARemain unaltered
- BIncrease
- CDecrease
- DBe zero
7.A differentially compounded dc motor is running at rated speed, if the series field winding of the motor gets short circuited, the speed of the motor will
- ARemains unaltered
- BIncrease
- CDecrease
- DBe zero
8.When the direction of power flow in a differentially compounded motor reverses, it will operate as a
- ACumulatively compounded generator
- BDifferentially compounded generator
- CSeries motor
- DShunt motor
9.A differentially compounded dc motor with interpoles and with brushes on the neutral axis is to be driven as a generator in the same direction with the same polarity of the terminal voltage. It will then
- ABe a cumulatively compounded generator but the interpole coil connection are to be reverse
- BBe a cumulatively compounded generator without reversing the interpole coil connections
- CBe a differentially compounded generator without reversing the interpole coil connection
- DBe a differentially compounded generator but the interpole coli connection are to be reversed
10.Running the machine at no load is not recommended for
- ADC shunt motor
- BDC series motor
- CInduction motor
- DSynchronous motor
11.The dc motor suitable for applications requiring high starting torque is
- AShunt
- BSeries
- CCumulative compounded
- DDifferential compound
12.The dc motor that drawn almost same power at different loads is
- ACumulative compound
- BDifferential compound
- CSeries
- DShunt
13.Which of the following dc motor will have least percentage increase of input current, for the same percentage increase in torque?
- ACumulative compound
- BDifferential compound
- CShunt
- DSeries
14.Which of the following dc motors will run at the maximum speed on removal of load?
- ASeries
- BShunt
- CCumulative compound
- DDifferential compound
15.Which of the following dc motor has got maximum self-relieving property?
- AShunt
- BSeries
- CCumulative compound
- DDifferential compound
16.The dc motor, that has poorest speed regulation is
- ACumulative compound
- BDifferential compound
- CSeries
- DShunt
17.Which motor should not be used for centrifugal pumps?
- Ashunt
- Bseries
- Ccumulatively compound
- Ddifferentially compound
18.The ratio of the starting torque to full load torque is minimum in the case of
- Acumulative compound motors
- Bdifferential compound motors
- Cseries motors
- Dshunt motors
19.Which of the following dc motors has almost constant speed over their full load range?
- AShunt
- BSeries
- CCumulative compound
- DNone of these
20.Which of the dc motor will have highest percentage increase of input current, for the same percentage increase in torque?
- ASeries
- BShunt
- CCumulative compound
- DAll equal