Differential compound dc motors are applicable in which of the following load conditions?
AHigh starting torque loads
BLow starting torque loads
CFrequent on-off cycle loads
DVariable speed loads
Electrical Engineering · Question Bank
DC Motors
208 of 285 questions match · page 6 of 11. Answer in your head first, then check the solution.
Which one is main advantage of the Swinburne’s test on dc motors?
AIt is very economical and convenient
BIt ignores any change in the iron loss
CIt needs only one running test
DIt is applicable to both shunt and compound motors
Which one is main advantage of the Ward-Leonard system of dc motor speed controls?
AIt can be used for small motors
BIt has a high overall efficiency at all speeds
CIt uses a flywheel to reduce fluctuations in power demands
DIt gives smooth, sensitive and wide speed controls
What will happen if the supply terminals of a self-excited dc motor are interchanged?
AThe motor will run at its normal speed and in the same direction
BThe motor will run at its normal speed but in reverse direction
CThe motor will not run
DThe motor will run but at a lower speed
Which of the following is a function of the pole shoes in a dc motor?
ATo support the field coils
BTo spread out the flux
CTo reduce the reluctance of the magnetic path
DAll of these
Which one is an indication of a hot smoky motor?
AMotor windings are opened
BMotor windings are shorted
CMotor windings are grounded
DBoth B and C
At what size of loading is the back emf of a dc motor maximum?
AAt full load
BAt 50% load
CAt no load
DAt overload
What will happen to a dc series motor if plugged to an ac source at the same voltage?
AIt will run but with less efficiency
BIt will run slowly
CIt will overheat and get burn
DIt will not run
The operation of electric motors and generators depends on the interaction between the magnetic field and one of the following. Which one?
AElectric current
BElectric field
CCopper conductors
DBoth A and B
The bigger percentage of the power loss in a dc motor comes from which of the following?
AIron loss
BCopper loss
CStray power loss
DWindage loss
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
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
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
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
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
The friction and windage losses in a dc motor is dependent on which of the following?
ALine current
BFlux
CSpeed
DArmature current
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
Which of the following dc motors will speed up when load is increased?
ACumulative compound motors
BDifferential compound motors
CSeries motors
DShunt motors
Which of the following in a dc motor helps to produce unidirectional torque?
ABrushes
BCommutator
CEnd plates
DBoth A and B
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
More Electrical Engineering topics
- 1-Phase AC Circuits115
- 1P AC Circuits161
- 3-Phase AC Circuits83
- 3-Phase Induction Motors46
- 3P AC Circuits71
- 3P Induction Motors135
- Alternators157
- Basic Principles30
- circuits301
- Communications408
- Converters & Rectifiers59
- DC Circuits52
- DC Electric Circuits84
- DC Generators196
- Electrical Power Plant195
- Electrical Transients72
- Electromagnetic Induction68
- Electromagnetics350
- Electronics433
- Electrostatics100
- Energy Conversion357
- Engineering Materials117
- Faults106
- Fundamentals of Electricity141
- Illumination143
- Industrial Electronics205
- Instrumentation224
- Instruments & Measurements94
- Instruments and Measurements33
- Laws113
- Magnetic Circuits84
- Magnetism24
- Miscellaneous83
- Miscellaneous Topics33
- Network Laws & Theorems9
- Non-Sinusoidal Waveforms13
- Philippine Electrical Code33
- Power Factor Correction38
- Power Factor Corrections23
- Power Systems32
- Synchronous Motors112
- Transformers258
- Transmission Lines168