6035929
Questão 1
Questão
Reversing the DC current flow through an electrical coil will _____.
Responda
-
reverse its two-pole field
-
reduce the amount of flux produced
-
change its impedance
-
reduce the power consumed
Questão 2
Questão
A device which prints out a permanent record of the plant operating conditions is known as the _________.
Responda
-
data logger
-
analogger
-
bell logger
-
alarm logger
Questão 3
Questão
Engine room watch officers should keep a constant check on the loads carried by electric motors because _____.
Responda
-
exceeding nameplate value shortens useful life
-
low loads necessitate frequent insulation cleaning
-
residual magnetism may increase
-
energy is wasted if full loading is not utilized
Questão 4
Questão
The torque produced by a motor when the shaft will not turn, even though rated voltage is applied to the stator, is known as ___.
Responda
-
locked rotor torque
-
pullout torques
-
breakdown torque
-
torque margin
Questão 5
Questão
An operating characteristic appearing on the name plates of shipboard AC motors is____.
Responda
-
Temperature rise
-
type of overload protection
-
rated slip
-
locked rotor torque
Questão 6
Questão
Which of the following operating characteristics for DC motors is considered to give high starting torque?
Responda
-
series
-
shunt
-
cumulative-compound
-
differential-compound
Questão 7
Questão
What type of electric motor is commonly used to start small auxiliary diesel engines?
Responda
-
series
-
synchronous
-
cage
-
shunt
Questão 8
Questão
In a compound-wound motor, a portion of the line current flows through the ____.
Responda
-
shunt field coils
-
inertia poles
-
stator
-
frame
Questão 9
Questão
An advantage of DC motors over AC motors is that they ______.
Responda
-
offer infinite speed variations
-
are less expensive
-
require less maintenance
-
offer slow speed
Questão 10
Questão
The cycle per second developed by the alternator aboard your vessel is determined by ____.
Responda
-
the speed of the engine driving the alternator
-
the resistance applied to the field rheostat
-
the synchronous speed of induction
-
the adjustment made to the voltage regulator
Questão 11
Questão
One important difference between wye-connected and delta-connected generators is that delta connections have ____.
Responda
-
line voltage equal to the phase voltage
-
line voltages equal to the vector sum of the phase voltages
-
phase voltage 90º out of sync
-
line current equal to the phase current
Questão 12
Questão
A DC generator which is used to supply direct current in order to maintain an AC generator field is commonly known as a/an ______.
Responda
-
exciter
-
rotor
-
stator
-
armature
Questão 13
Questão
DC generator circuits are protected against malfunctions due to prime mover power loss by the use of ____
Responda
-
reverse current relays
-
main bus disconnect links
-
a separate battery back-up
-
reverse power relays
Questão 14
Questão
Armature cores in a DC generator are made of laminated steel sheets to ___.
Responda
-
reduce eddy current losses
-
fit the curvature of the frame
-
increase the hysteresis effect
-
allow for easy assembly
Questão 15
Questão
Modern DC generators are fitted with commutating poles to ____.
Responda
-
reduce sparking
-
prevent motorizing
-
reduce spring pressures ion the brushes
-
reduce the load on the main poles
Questão 16
Questão
The simplest method of controlling the terminal voltage of compound-wound DC generator is with a ____.
Responda
-
hand-operated field rheostat connected in series with line shunt field circuit
-
separate exciter in a series with the shunt field
-
carbon pile regulator in series with load
-
balance coil diverting neutral current through the shunt field
Questão 17
Questão
Which of the terms listed best describes a compound wound DC generator having a higher voltage at no load than at full load?
Responda
-
Under compound
-
Flat compound
-
Over compound
-
Terminal compound
Questão 18
Questão
Which of the following losses is/are present in every direct current generator armature?
I. Winding copper loss
II. Core eddy current loss
III. Magnetic hysteresis loss
Responda
-
I, II and III
-
I only
-
I and II only
-
II and III only
Questão 19
Questão
Regarding an induction motor, the output power developed is related to the ____.
Responda
-
slip of the rotor
-
speed of the rotating field
-
DC filed excitation
-
current flow in the interpoles
Questão 20
Questão
The difference between the synchronous speed of a three phase induction motor and its operating speed is called slip and may be correctly expressed as ___.
Responda
-
a percent of synchronous speed
-
the reduced amp rating
-
the decrease in shaft torque
-
reduced fuel consumption
Questão 21
Questão
The speed of a squirrel cage induction motor is determined by the ____.
Responda
-
number of the stator poles
-
diameter of the stator
-
bar resistance of the conducting rotor
-
motor winding resistance
Questão 22
Questão
The most practical method of controlling the RPM of a step-speed AC motor is to ____..
Responda
-
vary the number of poles
-
change input voltage
-
change the number of brushes
-
vary power factor
Questão 23
Questão
Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine ____.
Responda
-
slightly greater than the line frequency
-
slightly less than the line frequency
-
the same as the line frequency
-
greater than the line frequency
Questão 24
Questão
The division of kilowatt load between two paralleled alternators is determined by the ____.
Responda
-
load-speed characteristics of the governors
-
amount of field excitation to the leading machine
-
type of alternator
-
amount of field excitation to the lagging machine
Questão 25
Questão
The load sharing characteristics of two diesel alternators operating in parallel are directly related to the setting of their governors’_____.
Responda
-
speed droop
-
Load limit
-
idle speed
-
speed limit
Questão 26
Questão
Kilowatt load is divided between two AC generators operating in parallel by ____.
Responda
-
adjusting the governor controls
-
varying the excitation voltage
-
increasing both prime mover speeds simultaneously
-
decreasing both prime mover speeds simultaneously
Questão 27
Questão
The division of the reactive KVA load between paralleled AC generators is initiated by the ____.
Responda
-
voltage regulators
-
prime mover governors
-
proportioner
-
phase balance relay
Questão 28
Questão
After closing the circuit breaker to place tow similar alternators in parallel, the NEXT step is to balance the _____.
Responda
-
kilowatt load
-
power factor
-
voltage load
-
ampere load
Questão 29
Questão
If the energy input is significantly reduced to the prime mover of one ship board alternator operating in parallel with others, that alternator will ___.
Responda
-
begin to motorize and then trip out
-
continue to operate at no load
-
lose its load and tend to overspeed
-
slow down and operate at reduced load
Questão 30
Questão
When two AC generators are being paralleled, the breaker should be closed with the synchroscope pointer rotating in ____.
Responda
-
‘fast’ direction, just before the 12 o’clock position
-
‘slow’ direction, just before the 12 o’clock position
-
‘fast’ direction, just after the 12 o’clock position
-
‘slow’ direction, just after the 12 o’clock position
Questão 31
Questão
A change in field excitation of an alternator operating in parallel will cause a change in its _____________.
Responda
-
voltage output
-
alternator frequency
-
kilowatt load
-
current rating
Questão 32
Questão
The purpose of squirrel-cage windings in a synchronous motor is to ___.
Responda
-
provide a means for starting
-
provide more precise balancing
-
produce a higher power factor
-
eliminate arcing between the stator and the frame
Questão 33
Questão
Amortisseur windings are installed in a synchronous motor to ___.
Responda
-
provide a means for starting
-
reduce eddy current losses
-
produce a higher power factor
-
eliminate arcing between the stator and the rotor
Questão 34
Questão
A common source of field excitation for synchronous motors is a/an ______.
Responda
-
DC rectifier
-
low voltage battery
-
motor attenuator set
-
AC supply
Questão 35
Questão
An increase in which of the listed conditions will increase the speed of synchronous electric motor?
Responda
-
Frequency
-
Voltage
-
Armature current
-
Inductance
Questão 36
Questão
The speed of a synchronous motor is varied by ____.
Responda
-
changing the input frequency
-
interchanging any tow of the three live leads
-
changing the voltage of the system
-
increasing the field excitation
Questão 37
Questão
What is the approximate voltage per cell produced by the nickel-iron (Edison) battery?
Responda
-
1.35 volts
-
0.85 volts
-
6.05 volts
-
2.20 volts
Questão 38
Questão
Common nickel-cadmium and nickel-iron storage batteries utilize _____.
Responda
-
alkaline secondary cells
-
acid primary cells
-
alkaline primary cells
-
acid secondary cells
Questão 39
Questão
What is the approximate discharge voltage produced by one cell of a wet type nickel-cadmium battery?
Responda
-
1.25 volts
-
1.5 volts
-
2.2 volts
-
6.0 volts
Questão 40
Questão
The capacity of a storage battery is measured in ____.
Responda
-
ampere-hours
-
volts
-
volt-hours
Questão 41
Questão
Local action in a dry-cell, or lead storage battery is the process whereby ____.
Responda
-
the electrolyte compensates for overcharging
-
hydrogen gas is liberated
-
the battery becomes discharged without being connected to a load
-
potassium hydroxide absorbs carbon dioxide from the air
Questão 42
Questão
When mixing electrolyte, which if the following precautions should always be observed?
Responda
-
Add the acid to the water
-
Use a heavy duty aluminum pail
-
Add the water to the acid
-
Mix the solution outdoors
Questão 43
Questão
The normal open-circuit voltage of one cell of a fully charged lead-acid battery is ____.
Responda
-
2 volts
-
1.5 volts
-
12 volts
-
6 volts
Questão 44
Questão
When lead-acid batteries are charging, they always give off hydrogen gas that is ____.
Responda
-
highly explosive
-
considered inert
-
heavier than air
-
extremely toxic
Questão 45
Questão
When charging lead-acid batteries the charging rate should be reduced as the battery nears its full charge to ____.
Responda
-
prevent damaging battery plates
-
allow equalization of cell voltages
-
reduce lead sulfate deposits
-
increase lead peroxide formation
Questão 46
Questão
When a lead-acid battery gassing freely while receiving a normal charge, the charging current should be ____.
Responda
-
decreased
-
increased
-
shut off
-
unchanged
Questão 47
Questão
Violent gassing developed by a lead-acid battery during charging indicates that the ____.
Responda
-
charging rate is excessive
-
plate separators are grounded
-
cell voltages are excessive
-
specific gravity is insufficient
Questão 48
Questão
A nickel-cadmium battery is receiving a normal charge and gases freely. The charging current should ____.
Responda
-
remain the same
-
be decreased
-
be cut off and the battery allowed to cool
-
be increased
Questão 49
Questão
Battery charging rooms should be well ventilated because the charging process produces ____.
Responda
-
explosive gases
-
highly combustible oxygen
-
highly poisonous gas
-
corrosive gases
Questão 50
Questão
Protection against sustained overloads occurring in molded-case circuit breakers is provided by a/an ____.
Responda
-
thermal acting trip
-
overvoltage release
-
reverse current relay
-
low voltage relay
Questão 51
Questão
The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____.
Responda
-
directing the arc into an arc chute
-
designing the contacts to open slowly
-
an inverse timed thermal trip for short circuit currents
-
instantaneous magnetic trip for over load currents
Questão 52
Questão
Electrical circuits are protected against overheating by means of a/an ___.
Responda
-
circuit breaker
-
amplifier
-
diode
-
capacitor
Questão 53
Questão
The 24 volt DC bus on the emergency switchboard is used to supply power to the ___.
I. gyrocompass power failure alarm system
II. smoke detection system
III. general alarm system
Responda
-
I, II and III
-
I only
-
I and II only
-
II and III only
Questão 54
Questão
As storage battery for an emergency lighting and power system must have the capacity to ____.
Responda
-
close all watertight doors twice
-
open all watertight doors four time.
-
open and close all watertight doors in six consecutive cycles within a 20 second period
-
none of the above
Questão 55
Questão
Regulations require emergency diesel engine starting systems to have sufficient capacity to provide power for at least ____.
Responda
-
six consecutive cranking cycles
-
three continuous starting sequences
-
nine repeated starts under load
-
twelve cranking periods of 5 seconds
Questão 56
Questão
The source of emergency lighting and power at loss of normal ship’s power on a cargo vessel should be obtained from the ____.
Responda
-
emergency generator supply to the emergency switchboard
-
emergency generator supply to the main switchboard
-
battery supply to the main switchboard
-
turbogenerator supply to the emergency switchboard
Questão 57
Questão
An emergency generator driven by an internal combustion engine, shall be tested under load for a minimum of 2 hours at least once evry ___.
Responda
-
month
-
2 weeks
-
week
-
3 months
Questão 58
Questão
A bus disconnect link is used to isolate ___.
Responda
-
the generator circuit breaker from the bus
-
one bus bar from the ground detection system
-
different bus phases form the equalizer connection
-
positive and negative buses from the neutral
Questão 59
Questão
A ‘dead front’ switchboard is one ____.
Responda
-
with insulated switches and no exposed terminals
-
without switches on it
-
without circuit breakers
-
without safety hand rail nor rubber mats
Questão 60
Questão
Which of the following statements identifies the difference between the primary windings and the secondary windings of a 2:1 step down transformer?
Responda
-
The secondary windings have half as many turns as the primary windings
-
The secondary windings have twice as much resistance as the primary windings
-
The secondary windings use smaller wires than the primary windings
-
The secondary windings can only provide half as much current as the primary windings
Questão 61
Questão
Increasing the load on the secondary windings of a transformer will cause a/an _____.
Responda
-
increase in the primary current
-
decrease in the primary voltage
-
increase in the primary voltage
-
decrease in the primary current
Questão 62
Questão
Power transformers are rated in _____.
Responda
-
kilovoltamperes
-
kilowatt-amps
-
ampere-turns
-
kilowatt-volts
Questão 63
Questão
Relative to the secondary winding of a step-up transformer, the primary winding will have ____.
Responda
-
fewer turns
-
more turns
-
same number of turns but smaller wires
-
twice as many turns
Questão 64
Questão
When a transformer is used to step-down voltage, the low voltage winding is ___.
Responda
-
the secondary coil
-
part of the core
-
the primary coil
-
not insulated
Questão 65
Questão
In a three-phase, open-delta connected transformer, the line current is equal to ____.
Responda
-
the phase current
-
three times the phase current
-
the sum of any two phase currents
-
the difference of any two phase currents
Questão 66
Questão
Transformers are used onboard ships with AC generators to ____.
Responda
-
provide different voltage values to operate various types of electrical equipment
-
change line frequency
-
increase power output to modulating frequency controllers
-
decrease power output to modulating frequency controllers
Questão 67
Questão
Which of the listed transformers uses a single winding to produce voltage transformation?
Responda
-
Autotransformers
-
Stepup transformers
-
Stepdown transformers
-
Isolation transformers
Questão 68
Questão
A transformer works on the basic principle of ____.
Responda
-
mutual induction
-
self impedance
-
attraction and repulsion
-
increasing power
Questão 69
Questão
The basic operating principle of a transformer is attributed to ___.
Responda
-
electromagnetic induction
-
variance of a conductor in a magnetic fluid
-
mutual reaction
-
thermionic emission
Questão 70
Questão
If a transformer is connected to a DC source, the transformer will overload at the _____.
Responda
-
primary coil
-
contacts
-
secondary coil
-
core
Questão 71
Questão
Transformer cores are laminated to reduce ____.
Responda
-
eddy currents
-
secondary flux
-
leakage flux
-
tertiary flux
Questão 72
Questão
A transformer in an electric circuit serves to ___.
Responda
-
increase or decrease circuit voltage as required
-
generate its own electrical power
-
transform electrical energy into mechanical energy
-
convert AC current to DC current
Questão 73
Questão
In an alternating current electrical system, a low system power factor is a direct sign of ____.
Responda
-
a large inductive load
-
a large resistance load
-
a short in exciter field windings
-
a ground in exciter field windings
Questão 74
Questão
Voltage will always lead current in a/an_____.
Responda
-
inductive circuit
-
capacitive circuit
-
magnetic circuit
-
resistive circuit
Questão 75
Questão
When the voltage and the current developed in an AC circuit reach their peak values at the same time, the power factor is considered to be _____.
Responda
-
unity
-
lagging
-
leading
-
infinity
Questão 76
Questão
When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is ___.
Responda
-
maximum
-
lagging
-
leading
-
minimum
Questão 77
Questão
Capacitors can be used in electric distribution systems to improve power factor. This is accomplished by seesawing energy between the capacitor and the ____.
Responda
-
inductive loads
-
generator
-
resistive loads
-
transformer
Questão 78
Questão
Which of the following types of motors can be used for correcting power factor during normal operation?
Responda
-
Synchronous
-
Polyphase
-
Wound-rotor
-
Induction
Questão 79
Questão
Which of the substances listed can be used to shield sensitive equipment from static magnetic fields?
Responda
-
Permeable Iron
-
Glass
-
Mica
-
Bakelite
Questão 80
Questão
The purpose of a magnetic relay is to ______.
Responda
-
remotely open and close contacts
-
open a circuit only in the event of overload
-
provide overcurrent protection during starting
-
relay voltages at increased power
Questão 81
Questão
Incandescent lamps are classified according to ____.
I. shape of bulb and type of service
II. size and style of base
III. operating voltage and wattage
Responda
-
I, II and III
-
I only
-
I and II only
-
II and III only
Questão 82
Questão
An adjustable resistor, whose resistance can be changed without opening the circuit in which it is connected, is called a ____.
Responda
-
rheostat
-
bleeder resistor
-
bridge
-
variable shunt strip
Questão 83
Questão
A milliammeter with a full scale deflection reading of 100 milliamps is known to have an accuracy of plu or minus 2%. A meter reading of 5 milliamps would indicate a line current of between _____.
Responda
-
4.9 and 5.1 milliamperes
-
4.8 and 5.2 milliamperes
-
4.5 and 5.5 milliamperes
-
4.0 and 6.0 milliamperes
Questão 84
Questão
A DC ammeter would normally be connected ______.
Responda
-
in series with a circuit
-
in parallel with a circuit
-
with internal shunts only
-
without regard to polarity
Questão 85
Questão
If the approximate voltage to be measured in an electric circuit is not known, you should _____.
Responda
-
use the highest voltage range on the voltmeter
-
Use the lowest voltage range on the voltmeter
-
connect the meter in series with the circuit
-
only have to calibrate the meter before using it
Questão 86
Questão
The resistance value of a resistor in a circuit can best be determined by the ______.
Responda
-
band markings on the resistor
-
single solid body color of the resistor
-
amperage value written on the resistor
-
physical size of the resistor
Questão 87
Questão
The basic “control action” of a magnetic amplifier is dependent upon _____.
Responda
-
variations in the load capacities
-
changes in the inductance
-
the type of core material
-
the construction of the core
Questão 88
Questão
A general purpose electrical multimeter can be used to directly measure ____.
Responda
-
current
-
watts
-
field flux
-
all of the above
Questão 89
Questão
The Wheatstone bridge is a precision measuring instrument utilizing the principle of changes in ____.
Responda
-
resistance
-
inductance
-
capacitance
-
amperage
Questão 90
Questão
The RPM of an AC generator can be measured with a/an _____.
Responda
-
vibrating reed meter
-
ammeter
-
voltmeter
-
synchroscope
Questão 91
Questão
The shunt of a DC ammeter should be connected in _____.
Responda
-
series with the load and in parallel with the meter movement
-
parallel with the load in series with the meter movement
-
parallel with the load and in parallel with the meter movement
-
series with the load and in series with the meter movement
Questão 92
Questão
Which of the following statements represents the correct method of connecting the shunt of an ammeter prior to taking a reading?
Responda
-
In series with the load in parallel with the meter movement
-
In series with the load and in series with the meter movement
-
In parallel with the load and in series with the meter movement
-
In parallel with the load and in parallel with the meter movement
Questão 93
Questão
Which of the following meters uses a shunt connected in series with the load, but parallel with the meter movement?
Responda
-
ammeter
-
voltmeter
-
power factor meter
-
wattmeter
Questão 94
Questão
External shunts are sometimes used with ammeters to _____.
Responda
-
prevent damage to the meter movement from heat generated by the internal shunt
-
increase meter sensitivity
-
permit shunts with larger resistance to be utilized
-
reduce reactive power factor error
Questão 95
Questão
A millimeter, with a full scale deflection reading of 100 milliamps, is known to have an accuracy of plus or minus 20%. A meter reading of 10 milliamps would indicate a line current of between _____.
Responda
-
9.8 and 10.2 milliamperes
-
9.8 and 10.0 milliamperes
-
8.0 and 12.0 milliamperes
-
8.0 and 10.0 milliamperes
Questão 96
Questão
An ammeter reads slightly ‘zero’ when its lead are disconnected, this is a result of ______.
Responda
-
mechanical misalignment of the meter pointer
-
a poor ground for the meter case
-
static electricity in the air
-
resistor inside the meter storing charges
Questão 97
Questão
When a resistor is used as a shunt and is connected in parallel with a meter movement coil, it will provide _____.
Responda
-
an extended meter range
-
a measurement of circuit resistance
-
an increased accuracy of approximately 1.5 percent
-
none of the above
Questão 98
Questão
A galvanometer is an instrument used to measure ____.
Responda
-
very small amounts of current or voltage
-
thickness of galvanized metal
-
resistance of electrical wiring insulation
-
quantity of galvans in an electric circuit
Questão 99
Questão
To limit the current flow through a DC, voltmeter to as low a value as possible, the moving coil is provided with a/an ____.
Responda
-
high series resistance
-
high parallel resistance
-
series inductor
-
external shunt
Questão 100
Questão
AC voltmeters are generally calibrated to read the ____.
Responda
-
RMS voltage
-
instantaneous voltage
-
average voltage
-
peak voltage
Questão 101
Questão
Most AC voltmeters are calibrated to indicate ____.
Responda
-
root-mean-square voltage
-
peak-to-peak voltage
-
average voltage
-
peak voltage only
Questão 102
Questão
Conductor resistance may be INDIRECTLY measured by using a/an______.
Responda
-
voltmeter and an ammeter
-
voltmeter only
-
ammeter only
-
frequency meter
Questão 103
Questão
Which of the following statements regarding the use of a current measuring instrument is correct ?
Responda
-
It must be connected in series with the circuit
-
You should always start with the lowest range until a suitable reading is obtained
-
The indicating needle is deflected from left to right regardless of polarity
-
An external shunt is generally utilized where current is less than 10 amperes
Questão 104
Questão
Handheld electrical phase sequence indicators are useful when ____.
Responda
-
connecting shore power lines to the ship
-
preparing to parallel alternators
-
connecting lighting branch circuits
-
troubleshooting DC motors
Questão 105
Questão
Modern handheld non-contact digital tachometers operate by counting light pulses returned to the unit by _____.
Responda
-
a piece of reflective tape mounted in the shaft
-
the vibrating tach generator
-
the coupling bolts
-
a small bulb attached to the shaft
Questão 106
Questão
A handheld reflective digital tachometer could give a false reading it ____.
Responda
-
partially aimed at a 60HZ fluorescent light
-
aimed directly at the rotating shaft
-
positioned 5-10 inches from the rotating shaft
-
the tape is too shiny
Questão 107
Questão
Electrostatic forces in high voltage circuits cause indicating instruments to give ____.
Responda
-
inaccurate readings
-
parallax readings
-
highly intuitive readings
-
highly accurate readings
Questão 108
Questão
Fuses are usually rated in ___.
Responda
-
amps and volts
-
watts
-
volts only
-
amps only
Questão 109
Questão
Time delayed or delayed action-type fuses are designed to ___.
Responda
-
permit momentary overloads without melting
-
prevent grounds in branch circuits
-
prevent opens in motor circuits
-
guard lighting and electronic circuits
Questão 110
Questão
In a cartridge-type fuse, the metal element is contained in a ____.
Responda
-
fiber tube
-
porcelain window
-
thermal cut out
-
flasher device
Questão 111
Questão
Fuses placed in series with a thermal trip-type circuit breaker are used for ____.
Responda
-
short-circuit protection
-
time-delay protection
-
short duration surge protection
-
sustained overload protection
Questão 112
Questão
The energy consumed by AC motor, as strictly reactive power, is _____.
Responda
-
used to establish the magnetic field of the motor
-
used to do mechanical work
-
lost as heat generated by bearing friction
-
lost in doing work to turn the motor itself
Questão 113
Questão
A constant output voltage from an AC generator is maintained by the ___.
Responda
-
voltage regulator
-
prime mover governor
-
exciter generator
-
reverse power relay
Questão 114
Questão
The instantaneous reduction in voltage of an AC generator, resulting from an increase in load, and prior to the automatic voltage regulator correcting the situation, is called voltage ____.
Responda
-
dip
-
droop
-
drop
-
regulation
Questão 115
Questão
Prior to starting an AC generator prime mover, the voltage regulator selector switch should be placed in the ___.
Responda
-
manual position
-
bus neutral position
-
raise voltage position
-
transfer position
Questão 116
Questão
Which is a function of the voltage regulators used with AC generators?
Responda
-
To divide reactive current between generators operating in parallel
-
To cut out generators when they are no longer required
-
To cut in additional generators automatically as required
-
To divide the KW load equally between generators operating in parallel
Questão 117
Questão
The life expectancy of electrical insulation, is approximately hal;ved for an increased operating temperature of ___.
Responda
-
10ºC
-
25ºC
-
50ºC
-
100ºC
Questão 118
Questão
If a pointer on a megger fails to return to ‘zero’ when not being used, the ____.
Responda
-
megger is operating normally
-
megger is out of calibration
-
hairsprings are burned out
-
pointer probably stuck in that position
Questão 119
Questão
A multimeter may be damaged by taking a ___.
Responda
-
voltage reading while in the resistance mode
-
current reading while in the voltmeter mode
-
resistance reading while in the ammeter mode
-
resistance reading while in the voltmeter mode
Questão 120
Questão
In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This accomplished by opening the ___.
Responda
-
bus disconnect link
-
reverse power relay
-
generator bus fuse connections
-
power directional relay
Questão 121
Questão
When replacing fuses, always make sure ___.
Responda
-
the fuse clips are straight, tight, and in good contact
-
to stand on a rubber mat and use rubber gloves
-
to use insulated plier or screwdrivers
-
to increase the fuse rating 10% to guard against ‘nuisance blowing’
Questão 122
Questão
When working on electrical circuits containing large capacitors, in addition to de-energizing the circuit, which of the listed precaution should also be taken?
Responda
-
Ground the capacitor terminals
-
keep all radio equipment away
-
Measure capacitor insulation resistance
-
Check capacitor circuit polarity
Questão 123
Questão
The third color band on a resistor is used to indicate the_______.
Responda
-
number of zeros following the first two significant figures in the resistance value
-
tolerance of the resistor
-
first significant figure of the resistance
-
second significant figure of the resistance
Questão 124
Questão
Which of the listed conditions describes the effect on intrinsic semiconductor operation as a result of a temperature increase?
Responda
-
Conductivity will increase
-
Capacitive reactance will decrease
-
Inductive reactance will decrease
-
Resistivity will increase
Questão 125
Questão
A signal derived from a controlled function and returned to the initiating point is called a/an_____.
Responda
-
feedback signal
-
monitoring signal
-
inverse signal
-
reverse signal
Questão 126
Questão
Which of the following statements describes the significance of ambient temperature in relation to the service life of electronic components?
Responda
-
Increased ambient temperature decreases the service life of electronic components.
-
Ambient temperature should be as high as possible to drive off moisture.
-
Ambient temperature is not significant as long as the relative humidity is kept low.
-
A reduced ambient temperature causes a corresponding reduced service life.
Questão 127
Questão
The method used to produce electron emission in most vacuum tubes is known as______.
Responda
-
thermionic emission
-
photoelectric emission
-
secondary electric emission
-
cold cathodic electric emission
Questão 128
Questão
In electronic circuitry, the abbreviation 'PCB' commonly means________.
Responda
-
printed circuit board
-
pulse coded binary
-
poly -coated braid
-
personal computer bits
Questão 129
Questão
Which of the following statements concerning analog and digital devices are correct?
Responda
-
The variables in digital systems are fixed quantities, and the variables in analog systems are continuous quantities.
-
There are no basic differences between the two systems.
-
Analog devices are superior in accuracy compared to digital devices.
-
Operations in a digital device are performed simultaneously.
Questão 130
Questão
Which of the following statements correctly applies to transistors?
Responda
-
The three terminals are called the emitter, base, and collector.
-
LED and LCD are the two basic types of transistors.
-
The emitter separates the base and collector.
-
The collector separates the emitter and base.
Questão 131
Questão
A silicon controlled rectifier (SCR) is a solid state device used to change_______.
Responda
-
AC to DC and control relatively high load current
-
DC to AC and control relatively low load current
-
DC to AC and control relatively high load current
-
AC to DC and control relatively low load current
Questão 132
Questão
Silicon diodes which are designed for a specific reverse breakdown voltage, and are most often used in electronic power supply voltage regulators, are called________.
Responda
-
Zener diodes
-
tunnel diodes
-
hot -carrier diodes
-
compensating diodes
Questão 133
Questão
Which of the listed devices may be used as a digital device?
Responda
-
diode
-
variable resistor
-
strain gauge
-
thermistor
Questão 134
Questão
A triac thyristor functions as a control device and basically functions as______.
Responda
-
a bidirectional SCR with a common gate
-
two NPN transistors in parallel with a common base lead
-
a diode in series with a temperature sensitive capacitor
-
a triode tube with an extra heavy grid element
Questão 135
Questão
The purpose of a heat sink, as frequently used with transistors, is to______.
Responda
-
prevent excessive temperature rise
-
compensate for excessive doping
-
increase the reverse current
-
decrease the forward current
Questão 136
Questão
In process control terminology, continuously variable values which change without distinct increments, such as temperature, pressure, or level are called_______.
Responda
-
analog values
-
binary values
-
digital values
-
bumpless values
Questão 137
Questão
Increasing the power source frequency in a capacitive circuit will_____.
Responda
-
increase the average current in the circuit
-
decrease the average current on the circuit
-
not have any affect on the average current value
-
not have any affect on the capacitive reactance
Questão 138
Questão
An operational amplifier, as used in today's consoles, may have a calculated gain of 5. This means that as the input changes by______.
Responda
-
1 volt, the output changes 5 volts
-
5 volts, the output changes 1 volt
-
5 volts, the output changes 10 volts
-
10 volts, the output changes 5 volts
Questão 139
Questão
An operational amplifier, as used in today's consoles, has a calculated gain of 5. This means that when the input changes______.
Responda
-
2 volts, the output changes 10 volts
-
volts, the output changes 10 volts
-
10 volts, the output changes 5 volts
-
10 volts, the output changes 2 volts
Questão 140
Questão
Heat sinks are most frequently used with_____.
Responda
-
power transistors
-
vacuum tubes
-
LED's
-
LCD's
Questão 141
Questão
Which of the listed conditions is an advantage of a PN diode over a vacuum diode?
Responda
-
All of the above.
-
Smaller size.
-
No warm up time.
-
More reliable.
Questão 142
Questão
The schematic symbol for an operational amplifier in an analog circuit is a______.
Responda
-
triangle
-
circle
-
square
-
trapezoid
Questão 143
Questão
Which of the listed conditions is an advantage of a PN diode over a vacuum diode?
Responda
-
All of the above.
-
Longer life.
-
No warm up time.
-
Less delicate.
Questão 144
Questão
In a logic circuit, the NOT gate function______.
Responda
-
reverses an input logic condition
-
does not alter a logical input
-
serves to amplify a given signal level
-
must be accomplished with a common collector transistor arrangement
Questão 145
Questão
How many possible states does a binary logic circuit have?
Responda
-
Two
-
One
-
Three
-
Four
Questão 146
Questão
In a logic circuit the NOR and NAND gate functions______.
Responda
-
have output conditions that are exact opposites to the output condition for OR and AND, respectively
-
must be accomplished with a common base transistor
-
arrangement are available in diode form
-
are exact opposites with the same NOR and NAND inputs
Questão 147
Questão
Which of the listed logic gates is considered to be a BASIC building block (basic logic gate) used in logic diagrams?
Responda
-
OR
-
NAND
-
NOR
-
All of the above.
Questão 148
Questão
In a diesel electric plant, raising the AC generator's field excitation will cause the DC propulsion motor to______.
Responda
-
increase in speed
-
decrease in speed
-
operate with a lower power factor
-
operate with a higher power factor
Questão 149
Questão
Equipment for dc propulsion drive systems usually includes_________.
Responda
-
generators which produce ac power that is converted to dc for the propulsion motor
-
generators which produce dc power that is converted to ac power for the propulsion motor
-
a synchronous type propulsion motor
-
an induction type propulsion motor
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