Reversing the DC current flow through an electrical coil will _____.
reverse its two-pole field
reduce the amount of flux produced
change its impedance
reduce the power consumed
A device which prints out a permanent record of the plant operating conditions is known as the _________.
data logger
analogger
bell logger
alarm logger
Engine room watch officers should keep a constant check on the loads carried by electric motors because _____.
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
The torque produced by a motor when the shaft will not turn, even though rated voltage is applied to the stator, is known as ___.
locked rotor torque
pullout torques
breakdown torque
torque margin
An operating characteristic appearing on the name plates of shipboard AC motors is____.
Temperature rise
type of overload protection
rated slip
Which of the following operating characteristics for DC motors is considered to give high starting torque?
series
shunt
cumulative-compound
differential-compound
What type of electric motor is commonly used to start small auxiliary diesel engines?
synchronous
cage
In a compound-wound motor, a portion of the line current flows through the ____.
shunt field coils
inertia poles
stator
frame
An advantage of DC motors over AC motors is that they ______.
offer infinite speed variations
are less expensive
require less maintenance
offer slow speed
The cycle per second developed by the alternator aboard your vessel is determined by ____.
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
One important difference between wye-connected and delta-connected generators is that delta connections have ____.
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
A DC generator which is used to supply direct current in order to maintain an AC generator field is commonly known as a/an ______.
exciter
rotor
armature
DC generator circuits are protected against malfunctions due to prime mover power loss by the use of ____
reverse current relays
main bus disconnect links
a separate battery back-up
reverse power relays
Armature cores in a DC generator are made of laminated steel sheets to ___.
reduce eddy current losses
fit the curvature of the frame
increase the hysteresis effect
allow for easy assembly
Modern DC generators are fitted with commutating poles to ____.
reduce sparking
prevent motorizing
reduce spring pressures ion the brushes
reduce the load on the main poles
The simplest method of controlling the terminal voltage of compound-wound DC generator is with a ____.
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
Which of the terms listed best describes a compound wound DC generator having a higher voltage at no load than at full load?
Under compound
Flat compound
Over compound
Terminal compound
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
I, II and III
I only
I and II only
II and III only
Regarding an induction motor, the output power developed is related to the ____.
slip of the rotor
speed of the rotating field
DC filed excitation
current flow in the interpoles
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 ___.
a percent of synchronous speed
the reduced amp rating
the decrease in shaft torque
reduced fuel consumption
The speed of a squirrel cage induction motor is determined by the ____.
number of the stator poles
diameter of the stator
bar resistance of the conducting rotor
motor winding resistance
The most practical method of controlling the RPM of a step-speed AC motor is to ____..
vary the number of poles
change input voltage
change the number of brushes
vary power factor
Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine ____.
slightly greater than the line frequency
slightly less than the line frequency
the same as the line frequency
greater than the line frequency
The division of kilowatt load between two paralleled alternators is determined by the ____.
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
The load sharing characteristics of two diesel alternators operating in parallel are directly related to the setting of their governors’_____.
speed droop
Load limit
idle speed
speed limit
Kilowatt load is divided between two AC generators operating in parallel by ____.
adjusting the governor controls
varying the excitation voltage
increasing both prime mover speeds simultaneously
decreasing both prime mover speeds simultaneously
The division of the reactive KVA load between paralleled AC generators is initiated by the ____.
voltage regulators
prime mover governors
proportioner
phase balance relay
After closing the circuit breaker to place tow similar alternators in parallel, the NEXT step is to balance the _____.
kilowatt load
power factor
voltage load
ampere load
If the energy input is significantly reduced to the prime mover of one ship board alternator operating in parallel with others, that alternator will ___.
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
When two AC generators are being paralleled, the breaker should be closed with the synchroscope pointer rotating in ____.
‘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
A change in field excitation of an alternator operating in parallel will cause a change in its _____________.
voltage output
alternator frequency
current rating
The purpose of squirrel-cage windings in a synchronous motor is to ___.
provide a means for starting
provide more precise balancing
produce a higher power factor
eliminate arcing between the stator and the frame
Amortisseur windings are installed in a synchronous motor to ___.
eliminate arcing between the stator and the rotor
A common source of field excitation for synchronous motors is a/an ______.
DC rectifier
low voltage battery
motor attenuator set
AC supply
An increase in which of the listed conditions will increase the speed of synchronous electric motor?
Frequency
Voltage
Armature current
Inductance
The speed of a synchronous motor is varied by ____.
changing the input frequency
interchanging any tow of the three live leads
changing the voltage of the system
increasing the field excitation
What is the approximate voltage per cell produced by the nickel-iron (Edison) battery?
1.35 volts
0.85 volts
6.05 volts
2.20 volts
Common nickel-cadmium and nickel-iron storage batteries utilize _____.
alkaline secondary cells
acid primary cells
alkaline primary cells
acid secondary cells
What is the approximate discharge voltage produced by one cell of a wet type nickel-cadmium battery?
1.25 volts
1.5 volts
2.2 volts
6.0 volts
The capacity of a storage battery is measured in ____.
ampere-hours
volts
volt-hours
Local action in a dry-cell, or lead storage battery is the process whereby ____.
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
When mixing electrolyte, which if the following precautions should always be observed?
Add the acid to the water
Use a heavy duty aluminum pail
Add the water to the acid
Mix the solution outdoors
The normal open-circuit voltage of one cell of a fully charged lead-acid battery is ____.
2 volts
12 volts
6 volts
When lead-acid batteries are charging, they always give off hydrogen gas that is ____.
highly explosive
considered inert
heavier than air
extremely toxic
When charging lead-acid batteries the charging rate should be reduced as the battery nears its full charge to ____.
prevent damaging battery plates
allow equalization of cell voltages
reduce lead sulfate deposits
increase lead peroxide formation
When a lead-acid battery gassing freely while receiving a normal charge, the charging current should be ____.
decreased
increased
shut off
unchanged
Violent gassing developed by a lead-acid battery during charging indicates that the ____.
charging rate is excessive
plate separators are grounded
cell voltages are excessive
specific gravity is insufficient
A nickel-cadmium battery is receiving a normal charge and gases freely. The charging current should ____.
remain the same
be decreased
be cut off and the battery allowed to cool
be increased
Battery charging rooms should be well ventilated because the charging process produces ____.
explosive gases
highly combustible oxygen
highly poisonous gas
corrosive gases
Protection against sustained overloads occurring in molded-case circuit breakers is provided by a/an ____.
thermal acting trip
overvoltage release
reverse current relay
low voltage relay
The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____.
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
Electrical circuits are protected against overheating by means of a/an ___.
circuit breaker
amplifier
diode
capacitor
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
As storage battery for an emergency lighting and power system must have the capacity to ____.
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
Regulations require emergency diesel engine starting systems to have sufficient capacity to provide power for at least ____.
six consecutive cranking cycles
three continuous starting sequences
nine repeated starts under load
twelve cranking periods of 5 seconds
The source of emergency lighting and power at loss of normal ship’s power on a cargo vessel should be obtained from the ____.
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
An emergency generator driven by an internal combustion engine, shall be tested under load for a minimum of 2 hours at least once evry ___.
month
2 weeks
week
3 months
A bus disconnect link is used to isolate ___.
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
A ‘dead front’ switchboard is one ____.
with insulated switches and no exposed terminals
without switches on it
without circuit breakers
without safety hand rail nor rubber mats
Which of the following statements identifies the difference between the primary windings and the secondary windings of a 2:1 step down transformer?
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
Increasing the load on the secondary windings of a transformer will cause a/an _____.
increase in the primary current
decrease in the primary voltage
increase in the primary voltage
decrease in the primary current
Power transformers are rated in _____.
kilovoltamperes
kilowatt-amps
ampere-turns
kilowatt-volts
Relative to the secondary winding of a step-up transformer, the primary winding will have ____.
fewer turns
more turns
same number of turns but smaller wires
twice as many turns
When a transformer is used to step-down voltage, the low voltage winding is ___.
the secondary coil
part of the core
the primary coil
not insulated
In a three-phase, open-delta connected transformer, the line current is equal to ____.
the phase current
three times the phase current
the sum of any two phase currents
the difference of any two phase currents
Transformers are used onboard ships with AC generators to ____.
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
Which of the listed transformers uses a single winding to produce voltage transformation?
Autotransformers
Stepup transformers
Stepdown transformers
Isolation transformers
A transformer works on the basic principle of ____.
mutual induction
self impedance
attraction and repulsion
increasing power
The basic operating principle of a transformer is attributed to ___.
electromagnetic induction
variance of a conductor in a magnetic fluid
mutual reaction
thermionic emission
If a transformer is connected to a DC source, the transformer will overload at the _____.
primary coil
contacts
secondary coil
core
Transformer cores are laminated to reduce ____.
eddy currents
secondary flux
leakage flux
tertiary flux
A transformer in an electric circuit serves to ___.
increase or decrease circuit voltage as required
generate its own electrical power
transform electrical energy into mechanical energy
convert AC current to DC current
In an alternating current electrical system, a low system power factor is a direct sign of ____.
a large inductive load
a large resistance load
a short in exciter field windings
a ground in exciter field windings
Voltage will always lead current in a/an_____.
inductive circuit
capacitive circuit
magnetic circuit
resistive circuit
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 _____.
unity
lagging
leading
infinity
When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is ___.
maximum
minimum
Capacitors can be used in electric distribution systems to improve power factor. This is accomplished by seesawing energy between the capacitor and the ____.
inductive loads
generator
resistive loads
transformer
Which of the following types of motors can be used for correcting power factor during normal operation?
Synchronous
Polyphase
Wound-rotor
Induction
Which of the substances listed can be used to shield sensitive equipment from static magnetic fields?
Permeable Iron
Glass
Mica
Bakelite
The purpose of a magnetic relay is to ______.
remotely open and close contacts
open a circuit only in the event of overload
provide overcurrent protection during starting
relay voltages at increased power
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
An adjustable resistor, whose resistance can be changed without opening the circuit in which it is connected, is called a ____.
rheostat
bleeder resistor
bridge
variable shunt strip
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 _____.
4.9 and 5.1 milliamperes
4.8 and 5.2 milliamperes
4.5 and 5.5 milliamperes
4.0 and 6.0 milliamperes
A DC ammeter would normally be connected ______.
in series with a circuit
in parallel with a circuit
with internal shunts only
without regard to polarity
If the approximate voltage to be measured in an electric circuit is not known, you should _____.
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
The resistance value of a resistor in a circuit can best be determined by the ______.
band markings on the resistor
single solid body color of the resistor
amperage value written on the resistor
physical size of the resistor
The basic “control action” of a magnetic amplifier is dependent upon _____.
variations in the load capacities
changes in the inductance
the type of core material
the construction of the core
A general purpose electrical multimeter can be used to directly measure ____.
current
watts
field flux
all of the above
The Wheatstone bridge is a precision measuring instrument utilizing the principle of changes in ____.
resistance
inductance
capacitance
amperage
The RPM of an AC generator can be measured with a/an _____.
vibrating reed meter
ammeter
voltmeter
synchroscope
The shunt of a DC ammeter should be connected in _____.
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
Which of the following statements represents the correct method of connecting the shunt of an ammeter prior to taking a reading?
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
Which of the following meters uses a shunt connected in series with the load, but parallel with the meter movement?
power factor meter
wattmeter
External shunts are sometimes used with ammeters to _____.
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
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 _____.
9.8 and 10.2 milliamperes
9.8 and 10.0 milliamperes
8.0 and 12.0 milliamperes
8.0 and 10.0 milliamperes
An ammeter reads slightly ‘zero’ when its lead are disconnected, this is a result of ______.
mechanical misalignment of the meter pointer
a poor ground for the meter case
static electricity in the air
resistor inside the meter storing charges
When a resistor is used as a shunt and is connected in parallel with a meter movement coil, it will provide _____.
an extended meter range
a measurement of circuit resistance
an increased accuracy of approximately 1.5 percent
A galvanometer is an instrument used to measure ____.
very small amounts of current or voltage
thickness of galvanized metal
resistance of electrical wiring insulation
quantity of galvans in an electric circuit
To limit the current flow through a DC, voltmeter to as low a value as possible, the moving coil is provided with a/an ____.
high series resistance
high parallel resistance
series inductor
external shunt
AC voltmeters are generally calibrated to read the ____.
RMS voltage
instantaneous voltage
average voltage
peak voltage
Most AC voltmeters are calibrated to indicate ____.
root-mean-square voltage
peak-to-peak voltage
peak voltage only
Conductor resistance may be INDIRECTLY measured by using a/an______.
voltmeter and an ammeter
voltmeter only
ammeter only
frequency meter
Which of the following statements regarding the use of a current measuring instrument is correct ?
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
Handheld electrical phase sequence indicators are useful when ____.
connecting shore power lines to the ship
preparing to parallel alternators
connecting lighting branch circuits
troubleshooting DC motors
Modern handheld non-contact digital tachometers operate by counting light pulses returned to the unit by _____.
a piece of reflective tape mounted in the shaft
the vibrating tach generator
the coupling bolts
a small bulb attached to the shaft
A handheld reflective digital tachometer could give a false reading it ____.
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
Electrostatic forces in high voltage circuits cause indicating instruments to give ____.
inaccurate readings
parallax readings
highly intuitive readings
highly accurate readings
Fuses are usually rated in ___.
amps and volts
volts only
amps only
Time delayed or delayed action-type fuses are designed to ___.
permit momentary overloads without melting
prevent grounds in branch circuits
prevent opens in motor circuits
guard lighting and electronic circuits
In a cartridge-type fuse, the metal element is contained in a ____.
fiber tube
porcelain window
thermal cut out
flasher device
Fuses placed in series with a thermal trip-type circuit breaker are used for ____.
short-circuit protection
time-delay protection
short duration surge protection
sustained overload protection
The energy consumed by AC motor, as strictly reactive power, is _____.
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
A constant output voltage from an AC generator is maintained by the ___.
voltage regulator
prime mover governor
exciter generator
reverse power relay
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 ____.
dip
droop
drop
regulation
Prior to starting an AC generator prime mover, the voltage regulator selector switch should be placed in the ___.
manual position
bus neutral position
raise voltage position
transfer position
Which is a function of the voltage regulators used with AC generators?
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
The life expectancy of electrical insulation, is approximately hal;ved for an increased operating temperature of ___.
10ºC
25ºC
50ºC
100ºC
If a pointer on a megger fails to return to ‘zero’ when not being used, the ____.
megger is operating normally
megger is out of calibration
hairsprings are burned out
pointer probably stuck in that position
A multimeter may be damaged by taking a ___.
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
In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This accomplished by opening the ___.
bus disconnect link
generator bus fuse connections
power directional relay
When replacing fuses, always make sure ___.
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’
When working on electrical circuits containing large capacitors, in addition to de-energizing the circuit, which of the listed precaution should also be taken?
Ground the capacitor terminals
keep all radio equipment away
Measure capacitor insulation resistance
Check capacitor circuit polarity
The third color band on a resistor is used to indicate the_______.
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
Which of the listed conditions describes the effect on intrinsic semiconductor operation as a result of a temperature increase?
Conductivity will increase
Capacitive reactance will decrease
Inductive reactance will decrease
Resistivity will increase
A signal derived from a controlled function and returned to the initiating point is called a/an_____.
feedback signal
monitoring signal
inverse signal
reverse signal
Which of the following statements describes the significance of ambient temperature in relation to the service life of electronic components?
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.
The method used to produce electron emission in most vacuum tubes is known as______.
photoelectric emission
secondary electric emission
cold cathodic electric emission
In electronic circuitry, the abbreviation 'PCB' commonly means________.
printed circuit board
pulse coded binary
poly -coated braid
personal computer bits
Which of the following statements concerning analog and digital devices are correct?
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.
Which of the following statements correctly applies to transistors?
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.
A silicon controlled rectifier (SCR) is a solid state device used to change_______.
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
Silicon diodes which are designed for a specific reverse breakdown voltage, and are most often used in electronic power supply voltage regulators, are called________.
Zener diodes
tunnel diodes
hot -carrier diodes
compensating diodes
Which of the listed devices may be used as a digital device?
variable resistor
strain gauge
thermistor
A triac thyristor functions as a control device and basically functions as______.
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
The purpose of a heat sink, as frequently used with transistors, is to______.
prevent excessive temperature rise
compensate for excessive doping
increase the reverse current
decrease the forward current
In process control terminology, continuously variable values which change without distinct increments, such as temperature, pressure, or level are called_______.
analog values
binary values
digital values
bumpless values
Increasing the power source frequency in a capacitive circuit will_____.
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
An operational amplifier, as used in today's consoles, may have a calculated gain of 5. This means that as the input changes by______.
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
An operational amplifier, as used in today's consoles, has a calculated gain of 5. This means that when the input changes______.
2 volts, the output changes 10 volts
volts, the output changes 10 volts
10 volts, the output changes 2 volts
Heat sinks are most frequently used with_____.
power transistors
vacuum tubes
LED's
LCD's
Which of the listed conditions is an advantage of a PN diode over a vacuum diode?
All of the above.
Smaller size.
No warm up time.
More reliable.
The schematic symbol for an operational amplifier in an analog circuit is a______.
triangle
circle
square
trapezoid
Longer life.
Less delicate.
In a logic circuit, the NOT gate function______.
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
How many possible states does a binary logic circuit have?
Two
One
Three
Four
In a logic circuit the NOR and NAND gate functions______.
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
Which of the listed logic gates is considered to be a BASIC building block (basic logic gate) used in logic diagrams?
OR
NAND
NOR
In a diesel electric plant, raising the AC generator's field excitation will cause the DC propulsion motor to______.
increase in speed
decrease in speed
operate with a lower power factor
operate with a higher power factor
Equipment for dc propulsion drive systems usually includes_________.
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