Electrical Engineering · Question Bank
DC Motors
218 of 285 questions match · page 7 of 11. Answer in your head first, then check the solution.
#121📘 EE Pocket Reviewer RojasEasy
Which one describes the purpose of a dc motor?
AIt is a machine used to amplify the mechanical input of the machine
BIt is a machine used to convert mechanical to electrical energy
CIt is a machine used to convert electrical to mechanical energy
DIt is a machine used to generate mechanical energy
#122📘 EE Pocket Reviewer RojasEasy
If the speed of a dc motor will increase, what will happen to its armature current?
AIt increases
BIt decreases
CIt remains constant
DIt increases or decreases depending on the type of dc motor
#123📘 EE Pocket Reviewer RojasEasy
Which of the following is correct?
ACompound motors are used in flywheel drives
BSeries motors are used in belt drives
CShunt motors are used in electric trains
DSeries motors are used in machine tools
#124📘 EE Pocket Reviewer RojasEasy
If a dc series motor is operated on ac supply, which one will happen?
AThe motor will have poor efficiency
BThe motor will have poor power factor
CThe motor will spark excessively
DAll of these
#125📘 EE Pocket Reviewer RojasEasy
Which of the following conditions causes a series motor to overspeed?
AThe field circuit is opened
BThe load is removed
CThe supply voltage drops
DThe load is increased
#126📘 EE Pocket Reviewer RojasEasy
The friction and windage losses in a dc motor is dependent on which of the following?
ALine current
BFlux
CSpeed
DArmature current
#127📘 EE Pocket Reviewer RojasEasy
Which test is the usual test used in determining the efficiency of a traction motor?
AField's test
BRetardation test
CHopkinson's test
DSwinburne’s test
#128📘 EE Pocket Reviewer RojasEasy
Which of the following dc motors will speed up when load is increased?
ACumulative compound motors
BDifferential compound motors
CSeries motors
DShunt motors
#129📘 EE Pocket Reviewer RojasEasy
Which of the following in a dc motor helps to produce unidirectional torque?
ABrushes
BCommutator
CEnd plates
DBoth A and B
#130📘 EE Pocket Reviewer RojasEasy
What is the reason why the series field winding of a series motor are made from bigger wires?
ATo provide more flux
BTo reduce the eddy current loss in the winding
CTo reduce the insulating material used in the winding
DThe winding carries bigger current
#131📘 EE Pocket Reviewer RojasEasy
The armature current drawn by a dc motor is proportional to which of the following?
ATorque of the motor
BFlux in the field poles of the motor
CSupply voltage of the motor
DSpeed of the motor
#132📘 EE Pocket Reviewer RojasEasy
What type of dc motor is used in vacuum cleaners?
AShunt motor
BSeries motor
CCumulative compound motor
DDifferential compound motor
#133📘 EE Pocket Reviewer RojasEasy
What will happen if a series motor is started without a load?
AThe starting torque is very high
BThe starting current is very high
CThe starting speed is very high
DAll of these
#134📘 EE Pocket Reviewer RojasEasy
Which loss occurs in the yoke of a dc motor?
AIron loss
BCopper loss
CFriction and windage loss
DNo loss
#135📘 EE Pocket Reviewer RojasEasy
When load is increased, what will happen to the speed of a dc shunt motor?
AIt will reduce slightly
BIt will remain constant
CIt will also increase proportionately
DIt will increase slightly
#136📘 EE Pocket Reviewer RojasEasy
The Ward-Leonard system of speed controls can't be used in which of the following applications?
AVery low speed
BFrequent motor reversals
CConstant speed operation
DWide speed range
#137📘 EE Pocket Reviewer RojasEasy
Which of the following dc motors are used in heavy starting torque loads?
ASeries motors
BShunt motors
CLong-shunt compound motors
DShort-shunt compound motors
#138📘 EE Pocket Reviewer RojasEasy
What will happen if the back emf of a dc motor is not present?
AThe motor will burn
BThe motor will not run
CThe motor will run at very high speed
DThe motor will run at very low speed
#139📘 EE Pocket Reviewer RojasEasy
At present, dc motors are widely used in which of the following applications?
AAir compressors
BMachine shops
CElectric traction
DPumps
#140📘 EE Pocket Reviewer RojasEasy
Which of the following dc motors is best for high starting torque load applications?
ASeries motors
BShunt motors
CCumulative compound motors
DDifferential compound motors
More Electrical Engineering topics
