WorksheetsElectricidad 4
Total questions: 50
Worksheet time: 25mins
The sub-multiple prefix 'nano' (n) means __________.
thousandth (10 to the -3rd power)
millionth (10 to the -6th power)
billionth (10 to the -9th power)
trillionth (10 to the -12th power)
Which of the procedures listed could result in damaging a transistor beyond repair?
Applying incorrect polarity to the collector circuit.
Applying excessive voltage to the input circuit.
Careless soldering which would overheat the transistor.
All of the above.
Which of the listed instruments can be best used to locate a grounded field coil in a synchronous motor?
Frequency meter
Megohmmeter
Voltmeter
Multimeter
Which type of AC single-phase motor will also operate on direct current?
Split-phase
Series-wound
Shaded-pole
Repulsion-start
The standard procedure for maintaining the charge in an emergency diesel starting battery is to trickle charge the battery __________.
continuously
at least once each week
whenever the charge falls to 75% of full charge
whenever the electrolyte specific gravity falls to 1.250 or lower
The electrical energy necessary to power a sound-powered telephone's small vibrating bell is obtained from __________.
the emergency batteries for the general alarm
each station's hand-cranked generator
the emergency switchboard
normal 115 volt DC supplies
Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an __________.
small wire brush
compressed air jet
clean dry cloth
10% solution carbon solvent and water
If a delicate component must be soldered into a circuit, the component may be protected from the heat of the soldering process by __________.
operating the soldering gun not more than 60 seconds at a time
using a thermal shunt heat sink
pre-oxidizing the leads to be soldered
coating the leads to be soldered with a light oil film
If you disconnect and arrange both ends of a three conductor cable, without any contact between the individual conductors, a low ohmic value between the ends of a single conductor would indicate __________.
continuity of the conductor
an infinite resistance
the presence of a partial ground
that the conductor is not short circuited
Controller contacts should be routinely cleaned by __________.
blowing with compressed air
filing with a bastard file
wiping with a clean dry cloth
dressing with crocus cloth
The sub-multiple prefix 'pico' (p) means __________.
thousandth (10 to the -3rd power)
millionth (10 to the -6th power)
billionth (10 to the -9th power)
trillionth (10 to the -12th power)
When troubleshooting AC motors, a portable growler can be used for locating __________.
open field coils
grounded field coils
grounded stator coils
shorted stator coils
Which of the following methods should be used to dress the face of silver-plated contacts?
Filing
Burnishing
Sanding with 0000 sandpaper
All of the above are correct.
Common basic applications for the operational amplifier include __________.
counting, pulsing and clocking amplifiers
summing, scaling and difference amplifiers
step-up, step-down and rectifying amplifiers
all of the above
Handheld electrical phase sequence indicators are useful when __________.
preparing to parallel alternators
connecting lighting branch circuits
troubleshooting DC motors
connecting shore power lines to the ship
The set point current at which a magnetic-type overload relay tends to trip may be increased by turning the dashpot in the 'lower' direction. This action __________.
reduces magnetic force on the plunger and requires more current to trip the relay
reduces magnetic force on the plunger and requires less current to trip the relay
increases magnetic force on the plunger and requires more current to trip the relay
increases magnetic force on the plunger and requires less current to trip the relay
The timer element of a reverse power relay cannot be energized unless __________.
one generator is fully motorized
the movement of the disk is damped by a permanent magnet
the power flow is the same as the tripping direction
the power flow is the opposite to the tripping direction
A breakable, mercury-filled thermometer should not be used in a lead-acid battery to measure electrolyte temperature, as an accidental breakage can cause __________.
severe sparking and explosions
rapid oxidation of battery plates
violent gassing at the positive plates
corrosion on the battery terminals
Which of the listed statements is correct when using an analog multimeter as an ohmmeter?
The pointer should be adjusted to zero each time a new resistance range is selected.
The pointer will point to infinite ohms when the meter is not in use.
Ohmmeters are not sufficiently sized to accurately measure conductor insulation resistance.
All of the above.
Before working on an electric cargo winch master switch or controller, you should __________.
spray the gasket surface with a solvent
drain condensate from the box
open the circuit breaker in the power supply and tag-out
heat the switch box to remove any moisture
If a three-phase induction motor malfunctions and drops to a single-phase (one supply line open) __________.
the motor will continue to run if it is not heavily loaded
more torque will be developed
the motor will immediately stop and not be able to be restarted
the motor will immediately stop and can only be restarted at no load
In a three-phase circuit, the phase voltages are __________.
120° apart
160° apart
180° apart
360° apart
Which of the problems listed will occur if a lead-acid battery is allowed to remain in a discharged condition for a long period of time?
The battery may be unable to accept a full charge.
The electrolyte will change to lead sulfate.
The concentrated sulfuric acid will attack the lead peroxide plates.
The separators will harden.
Most three-phase induction motors of five horsepower or less, are started by __________.
autotransformer starters
resistor starters
across-the-line starters
reactor starters
When troubleshooting electronic equipment, the FIRST step to be taken before testing the circuit voltage is to __________.
set the meter to the lowest range
check the voltage supply from the power source
remove the suspected component
check the current flow through the circuit
Section II of the circuit shown in the illustration is the __________.
voltage regulator
filter
rectifier
voltage transformer
The division of kilowatt load between two paralleled alternators is determined by the __________.
amount of field excitation of the leading machine
load-speed characteristics of the governors
amount of field excitation to the lagging machine
type of alternator
When the current flow through a power transmission line is doubled, the power loss __________.
is halved
is doubled
is quadrupled
remains the same
An across-the-line starter provides __________.
maximum torque
slow starting power
high speed
reduced voltage
Transformers are used onboard ships with AC generators to __________.
change line frequency value
increase power output to modulating frequency controllers
decrease power output to modulating frequency controllers
provide different voltage values to operate various types of electrical equipment.
The full load torque of an electric motor is the __________.
minimum torque developed by the motor accelerating from stop to full speed
turning moment exerted by the motor at rated load and speed
maximum torque developed by the motor with rated voltage and frequency
turning moment exerted by the motor from any rotor angular position at any load
If you hear a loud buzzing noise coming from a magnetic motor controller, you should __________.
assume that the motor is operating at a full load
assume that the controller is operating normally
notify the electrician or watch engineer of the problem
feel the outside of the casing with your hand to see if it is hot
When lead-acid batteries are charging, they always give off hydrogen gas that is __________.
considered inert
highly explosive
extremely toxic
heavier than air
If the steering stand selector switch is allowed to remain in the 'Non-Follow-up' mode after testing of the steering gear, the rudder will __________.
not respond to commands from the helm
move in one direction only regardless of the movement of the helm
respond only to the output of the differential repeater
stop moving only when the helm is counter-rotated to put the pump at neutral stroke
A resistor placed in parallel to the output of a power supply __________.
is a temperature compensator
corrects power factor
prevents excessive currents
aids in output voltage regulation
In troubleshooting a circuit in a console, you find that a resistor may be faulty. Which of the precautions listed must be observed when using an ohmmeter to carry out this test?
Correct polarity must be observed, connecting the red lead to the banded end of the resistor.
Meter leads must be twisted to cancel the leads' magnetic fields.
The meter must be placed in series with the resistor and the circuit.
The resistor's circuit must be de-energized and at least one end of the component isolated.
When troubleshooting a magnetic controller, it is found that the contacts are welded together. The most probable cause is __________.
excessive operation at low load
high ambient temperature
low voltage on the operating coil
high voltage on the operating coil
Before measuring an unknown resistance with an ohmmeter, you should __________.
adjust the meter's pointer to mid-scale
short the test leads and calibrate the meter reading to 'zero'
change the meter's batteries
center the meter's pointer at infinity
A characteristic of a wound-rotor induction motor, with a high resistance rotor winding, is __________.
low starting torque
high starting torque
high speed
low starting voltage
Violent gassing from a lead-acid battery while it is being charged, indicates that the __________.
plate separators are grounded
battery compartment ventilation is inadequate
electrolyte specific gravity is too low
charging rate is too high
If a transformer is connected to a DC source, the transformer will overload at the __________.
contacts
primary coil
secondary coil
core
The output voltage of a 440 volt, 60 Hz AC generator is controlled by the __________.
load on the alternator
load on the prime mover
speed of the prime mover
exciter output voltage
When using an ohmmeter to test a semiconductor diode, you find a low resistance in both the forward and reverse bias directions. This indicates that the diode has a/an __________.
open
short
good resistive quality
good capacitive quality
Which of the following statements is true concerning the operating characteristics of a basic squirrel-cage induction motor?
Rotor slip is dependent upon the motor load.
An increase in motor load results in less slip.
A decrease in rotor speed results in less generated current.
A decrease in rotor speed produces a weaker magnetic field.
The speed of a squirrel-cage induction motor is determined by the __________.
diameter of the stator
number of stator poles
rotor winding resistance
rotor conducting bars resistance
A loud buzzing noise at the contacts of a magnetic controller could indicate __________.
weak contact spring pressure
misalignment of the magnet faces
excessive line current
mechanical binding
When mixing electrolyte for a lead-acid storage battery, __________.
stirring should always be avoided
a lead container should always be used
always pour the water into the acid
always pour the acid into the water
Excessive humming of AC contactors may be caused by __________.
burnt arc shields
shorted armature coils
a broken shading coil
high voltage
The specific gravity of the electrolyte in a lead-acid battery is measured by a __________.
gould plate
titration pipette
hydrometer
litmus paper test
The function of the commutator in a DC motor is to __________.
allow current flow in the armature windings under a given pole to be in the same direction at all times
reverse the flow of current in the field poles
reduce the reluctance of the magnetic path through the motor
shift the neutral running plane of the brushes to prevent sparking
