When cleaning a commutator which of the following is never used?
ASandpaper
BClean cloth
CEmery
DBoth A and B
Electrical Engineering · Question Bank
DC Generators
127 of 196 questions match · page 4 of 7. Answer in your head first, then check the solution.
In a dc machine, which one is a bigger loss in comparison to other losses?
AStray power loss
BCopper loss
CMechanical loss
DEddy current loss
Which of the following will cause generator brushes to burn?
ABrushes not in neutral plane
BGenerator overloaded
CWeak brush springs
DAll of these
Which generators would you prefer for feeding long dc transmission lines?
ASeries generator
BShunt generator
CFlat compounded generator
DOver-compounded generator
Which of the following losses occurs in the yoke of a dc generator?
AIron loss
BCopper loss
CHeat loss
DNo losses
In a dc generator, the generated emf is dependent on which of the following?
AFlux only
BSpeed only
CBoth flux and speed
DNeither flux nor speed
What is the purpose of laminating the armature core in a dc generator?
AReduce the eddy current loss
BInsulate the core from overheating
CProvide passage for cooling air
DReduce the weight of the core
How do you call a dc compound generator whose full-load terminal voltage is equal to the no-load terminal voltage?
AUnder-compounded
BFlat-compounded
CCumulative-compounded
DOver-compounded
Grooves around the circumference of a commutator indicates which of the following?
AHigh mica
BImproper brushes
COpen armature circuit
DImproper brush staggering
What is the purpose of staggering brushes?
ATo even out the load
BTo reduce chattering
CTo prevent the uneven wear on the commutator
DTo cover more area on the commutator segments
Equalizer rings are necessary in dc machines if the armature is using what type of windings?
AWave wound
BLap wound
CDuplex wound
DSimplex wound
What type of bearing is used to support the rotor shaft in a dc generator?
AMagnetic bearings
BBush bearings
CNeedle bearings
DBall bearings
Brushes in dc generators are made from which of the following?
ACarbon
BMica
CBronze
DCopper
Residual magnetism is necessary is which type of generators?
ASeparately-excited generators
BSelf-excited generators
CHigh voltage alternators
DLow voltage generators
Which of the following dc generators cannot build up on open circuit?
AShunt generator
BSeries generator
CShort shunt compound generator
DLong shunt compound generator
A belt driven cumulative compounded dc generator is delivering power to the dc mains. If the belt snaps, which one will likely to happen?
AThe machine will run as a cumulative compound motor running in the same direction
BThe machine will run as a cumulative compound motor running in the opposite direction
CThe machine will run as a differential compound motor running in the opposite direction
DThe machine will run as a differential compound motor running in the same direction
A dc generator has been exposed to water. Which of the following instruments would be used to determine if its safe to operate?
AA megger
BA voltmeter
CAn ammeter
DA wattmeter
DC generator voltage is increased by which of the following?
ABy cutting-in field resistance
BBy cutting-out field resistance
CBy cutting-in armature resistance
DBy cutting-out armature resistance
What is the material generally used for commutator brushes?
AMica
BCopper
CCast iron
DCarbon
In a dc generator, the number of commutator segments is equal to which of the following?
ANumber of turns
BNumber of coils
CNumber of slots
DNumber of coil sides
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 Motors285
- 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