- The full torque electric brake on an electric cargo winch functions to
.
A. act as a backup brake in the event the mechanical brake should fail
B. automatically hold the load as soon as current to the machine is shut off
C. automatically govern the lowering speed of the load
D. automatically govern the hoisting speed of the load
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ] B
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2.An electric tachometer receives the engine speed signal from a
……..
A. small generator mounted on the engine
B. bimetallic sensing device
C. stroboscopic sensing device
D. vibrating reed meter generating a voltage proportionate to engine speed
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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3.Which of the listed devices may be installed on a large turbo- electric alternating current propulsion generator?
A. Temperature detector coils inserted in the stator slots for measuring stator temperature.
B. A CO2 fire extinguishing system.
C. Electric space heaters to prevent condensation of moisture.
D. All of the above.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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4.5237 The output voltage of a 440 volt, 60 hertz, AC generator is controlled by the .
A. prime mover speed
B. exciter output voltage
C. load on the alternator
D. number of poles
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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- The electrolyte used in a nickel-cadmium battery is distilled water and .
A. diluted sulfuric acid
B. potassium hydroxide
C. lead sulfate
D. zinc oxide
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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6.While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates the .
A. motor has started properly
B. field windings are grounded
C. slip rings are dirty
D. power transmission cables are grounded
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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- Autotransformer starters or compensators are sometimes usedwith polyphase induction motors to .
A. reduce the voltage applied to the motor during the starting period
B. increase the voltage for “across-the-line starting”
C. provide a backup means of voltage regulation for emergency starting
D. allow the voltage to be either stepped up or down, depending on the application, to ensure full torque
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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8.Grounds occurring in electrical machinery as a result of insulation failure may result from .
A. deterioration through extended use
B. excessive heat
C. extended periods of vibration
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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9.When troubleshooting most electronic circuits, “loading effect” can be minimized by using a voltmeter with a/an
.
A. input impedance much greater than the impedance across which the voltage is being measured
B. input impedance much less than the impedance across which the voltage is being measured
C. sensitivity of less than 1000 ohms/volt
D. sensitivity of more than 1000 volts/ohm
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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10.A semiconductor that decreases in resistance with an increase in temperature is known as a .
A. resistor
B. thermistor
C. diode
D. thermopile
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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11.Moisture damage, as a result of condensation occurring inside of the cargo winch master switches, can be reducedby
.
A. installing a light bulb in the pedestal stand
B. coating the switch box internals with epoxy sealer
C. venting the switch box regularly
D. using strip heaters inside the switch box
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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12.Any electric motor can be constructed to be .
A. short proof
B. ground proof
C. explosion proof
D. overload proof
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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13.Which of the damages listed can occur to the components of a winch master control switch, if the cover gasket becomes deteriorated?
A. Overheating of the winch motor.
B. Contamination of lube oil.
C. Sparking at the winch motor brushes.
D. Rapid corrosion of switch components.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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14.The purpose of a short circuit forcing module (short time trip) installed in a branch line is to provide .
A. high speed clearance of low impedance short circuits in the branch
B. continuity of service on main bus under short circuit conditions in a branch
C. isolation of short circuits by selective tripping of branch circuit breakers
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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- In an AC synchronous motor electric propulsion plant,propeller speed is controlled by varying the .
A. prime mover speed
B. electric coupling field strength
C. number of energized main motor poles
D. propulsion generator field strength
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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16.The amount of voltage induced in the windings of an AC generator depends on .
A. the number of conductors in series per winding
B. the speed at which the magnetic field passes across the winding
C. the strength of the magnetic field
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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17.The device that most commonly utilizes the principle of
electromagnetic induction is the .
A. diode
B. transformer
C. transistor
D. rheostat
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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18.Which of the following statements concerning analog anddigital devices are correct?
A. The variables in digital systems are fixed quantities, and the variables in analog systems are continuous quantities.
B. There are no basic differences between the two systems.
C. Analog devices are superior in accuracy compared to digital devices.
D. Operations in a digital device are performed simultaneously.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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19.The current at which a magnetic-type overload relay tends to trip may be decreased by raising the plunger further into the magnetic circuit of the relay. This action .
A. reduces magnetic pull on the plunger and requires more current to trip the relay
B. reduces magnetic pull on the plunger and requires less current to trip the relay
C. increases magnetic pull on the plunger and requires more current to trip the relay
D. increases magnetic pull on the plunger and requires less current to trip the relay
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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20.Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in armature reaction are compensated for by the
A. governor speed droop setting
B. voltage regulator
C. balance coil
D. phase-balance relay
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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21.Electrical leads and insulation on a motor should be painted with
.
A. heat-resisting acrylic
B. heat-resisting aluminum
C. insulating varnish
D. insulating white lead
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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22.The alarm system for an engine order telegraph uses small selsyn motors attached to the indicators. The alarm soundswhen the rotors are .
A. in synchronous position, no current is flowing, and the relays are open
B. in synchronous position, no current is flowing, and the relays are closed
C. not synchronized, current is flowing, and the relays are open
D. not synchronized, current is flowing, and the relays are closed
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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- Which of the following statements is correct concerning the circuits in a sound powered telephone system?
A. The ringing circuit is composed of only one common wire to ground.
B. The common talking circuit is composed of two ungrounded wires.
C. The ringing circuit has two grounded wires connected to each station.
D. The talking and calling circuits are electrically dependent upon each other.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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24.AC circuits possess characteristics of resistance, inductance, and capacitance. The capacitive reactance of acircuit is expressed in
.
A. ohms
B. mhos
C. henrys
D. farads
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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25.A tubular fuse should always be removed from a fuse panel with
.
A. a screwdriver
B. a pair of insulated metal pliers
C. any insulated object
D. fuse pullers
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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26.The number of cells in a 12 volt lead-acid battery is
.
A. three cells
B. four cells
C. six cells
D. twelve cells
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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27.Protection against sustained overloads occurring in molded-case circuit breakers is provided by a/an .
A. overvoltage release
B. thermal acting trip
C. thermal overload relay
D. current overload relay
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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28.In an induction motor, rotor currents are circulated in therotor by
.
A. slip rings and brushes
B. an armature and brushes
C. inductive reaction of the rotating stator field
D. external variable resistors
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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Voltage generated by most AC generators is fed from the machine to the bus by means of .
A. brushes on a commutator
B. brushes on slip rings
C. slip rings on a commutator
D. direct connections from the stator
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to .
A. draw a one line diagram of the circuitry
B. test all fuses and measure the line voltage
C. take megger readings
D. insulate the apparatus from ground
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The first requirement for logical troubleshooting of any system is the ability to .
A. collect all available data on a casualty
B. recognize normal operation
C. identify the probable cause of a symptom
D. isolate the faulty component
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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A low voltage source is being used for testing armature coils. A coil short circuit will be indicated by a .
A. high voltage reading, while the other coil readings will have an equal or lower value
B. low or zero voltage reading, while the other coils will have higher readings
C. fluctuating voltmeter reading, while the other coil readings are steady
D. steady voltmeter reading, while the other coil readings are fluctuating
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The electrical energy necessary to transmit a person’s voice over a sound-powered telephone circuit is obtained from .
A. dry cell batteries
B. the ship’s service switchboard
C. the emergency switchboard
D. the speaker’s voice
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Which of the listed conditions is an advantage of a PNdiode over a vacuum diode?
A. Longer life.
B. No warm up time.
C. Less delicate.
D. All of the above.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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A shading coil used in an AC magnetic controller, functions to
.
A. reduce vibration and noise in the contactor
B. prevent flux buildup in the operating coil
C. eliminate arcing when the contacts close
D. energize the operating coil and “pull in” the contacts
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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- Time delayed or delayed action-type fuses are designed to
.
A. prevent grounds in branch circuits
B. prevent opens in motor circuits
C. permit momentary overloads without melting
D. guard lighting and electronic circuits
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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To effectively clean a commutator in good physical condition, you should use .
A. trichloride ethylene
B. kerosene
C. a canvas wiper
D. a commutator stone
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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When charging lead-acid batteries, you should reduce the charging rate as the battery nears its full charge capacity to .
A. prevent excessive gassing and overheating
B. allow equalization of cell voltages
C. reduce lead sulfate deposits
D. increase lead peroxide formation
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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Since fuse elements are made of zinc or any alloy of tin and lead, the melting point of the fuse element must be .
A. higher than that of copper
B. lower than that of copper
C. equal to that of copper
D. reached when the conductor it is protecting becomes “white hot.”
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Fuses are rated in .
A. voltage
B. amperage
C. interrupting capacity
D. all the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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A damper winding is designed as part of a synchronous motor to
.
A. increase efficiency
B. provide starting torque
C. provide excitation
D. eliminate slippage
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness?
A. Fill the motor housing with CO2 to inert the space.
B. Strap silica gel around the commutator.
C. Place heat lamps in the motor housings.
D. Cover the equipment with a canvas tarpaulin.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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The freezing point of the electrolyte in a fully charged lead-acid battery will be .
A. higher than in a discharged battery
B. lower than in a discharged battery
C. the same as in a discharged battery
D. higher than in a discharged battery, but the specific gravity will be less
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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In a cartridge-type fuse, the metal element is contained in a
.
A. porcelain window
B. thermal cut out
C. fiber tube
D. flasher device
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called .
A. tunnel diodes
B. hot-carrier diodes
C. compensating diodes
D. Zener diodes
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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What will be the phase angle relationship of a six-pole, three-phase, rotating field generator?
A. 60°
B. 120°
C. 180°
D. 360°
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Ammeters and voltmeters used in sinusoidal AC power systemsindicate which of the following values of the waveforms measured?
A. Peak value
B. Root-mean-square value
C. Average value
D. Maximum value
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Which of the following statements correctly applies to transistors?
A. NDN and PNP are the two basic types of transistors.
B. The three terminals are called the emitter, base, and collector.
C. The emitter separates the base and collector.
D. The collector separates the emitter and base.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Which of the following statements comparing transistors and vacuum tubes is correct?
A. Both transistors and vacuum tubes have a cathode that must be heated to give off electrons.
B. A vacuum tube must have a heated cathode, where transistors do not.
C. Neither transistors nor vacuum tubes require heat for electrons to flow.
D. The anode of both transistors and vacuum tubes must be heated to give off electrons.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The type of control circuit that will not permit automatic restarting after power is restored, following a power failure is called
.
A. low voltage protection
B. low voltage release
C. overload lockout
D. reduced voltage restart
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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- Which of the following types of motors is often designedfor use in correcting power factor?
A. Polyphase
B. Wound-rotor
C. Induction
D. Synchronous
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The purpose of amortisseur windings in a synchronous motor is to
.
A. reduce eddy current losses
B. produce a higher power factor
C. provide a means for starting
D. eliminate arcing between the stator and the rotor
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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High vacuum diodes, gas-filled diodes, and germanium semiconductor diodes may all be used as .
A. potentiometers
B. rectifiers
C. power sources
D. photocells
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Large cable sizes are formed as individual conductors that may be comprised of several smaller strands to .
A. obtain the flexibility required for easy handling
B. reduce the overall weight of the wire run
C. reduce the number of supports needed for a horizontal overhead run
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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A hydrometer indicates specific gravity by comparing the
.
A. density of a substance in water with the density of the same substance in air
B. differences in weight between water and the liquid measured
C. mass of substance measured with the density of the same substance
D. buoyancy of an object in water with the buoyancy of the same object in the liquid being measured
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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A common type of protective covering used on electrical conductors is .
A. plain paper
B. fibrous braid
C. silver sheathing
D. babbitt sheathing
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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An across-the-line starter is typically used for which of the following applications?
A. Reduced-current starting of large motors
B. Low torque starting of small motors
C. Low resistance starting of DC motors
D. Full-voltage starting of motors
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test, because the .
A. static charge of the machine may give a false reading
B. armature will have a greater number of leakage paths
C. insulation may be damaged
D. insulation may be covered with moisture
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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Which of the methods listed is used to maintain equal load sharing between two compound wound DC generators operating in parallel?
A. The shunt fields are interconnected.
B. The shunt field rheostats are interconnected.
C. The series fields of both generators are connected in series.
D. The series fields of both generators are connected in parallel.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Electric cables are formed of stranded wire to .
A. increase the current carrying capability for a given size wire
B. increase their flexibility
C. decrease the weight for a given size wire
D. assure good conductivity at junction points
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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A lead-acid battery is considered fully charged when the
.
A. electrolyte gasses freely
B. battery charger ammeter indicates a positive reading
C. terminal voltage reaches a constant value at a given temperature
D. specific gravity of all cells reaches the correct value and no longer increases over a period of 1 to 4 hours
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Local action in a dry-cell, or lead-acid storage battery is the process whereby .
A. hydrogen gas is liberated
B. the electrolyte compensates for overcharging
C. potassium hydroxide absorbs carbon dioxide from the air
D. the battery becomes discharged without being connected to a load
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The conversion of the throttle command voltage to thesignal necessary to achieve the desired shaft RPM isaccomplished by the
.
A. ahead or astern function generator of the throttle control circuit
B. feedback resistor of the summing amplifier circuit
C. operational amplifiers in the autorotation circuit
D. long time constant amplifier circuit
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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64.The unit of apparent power in a purely inductive circuit is called the
.
A. kva
B. var
C. emf
D. watt
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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- The main difference between an electron tube and a transistor is the .
A. type of function they can perform
B. reaction of electron flow through a gas or vacuum in a transistor
C. reaction of electron flow through a semiconductor when placed in a tube
D. reaction of electron flow through a semiconductor used to form a transistor
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The multiple prefix “kilo” means .
A. thousand (10 to the 3rd power)
B. million (10 to the 6th power)
C. billion (10 to the 9th power)
D. trillion (10 to the 12 power)
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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A double squirrel-cage motor is designed to have .
A. low starting torque
B. low starting current
C. high starting voltage
D. low starting resistance
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The rotor slots of a repulsion-type motor are generally skewed (placed nonparallel to the rotor axis) to .
A. produce a constant starting torque
B. permit a greater air gap with the starter
C. permit a smaller air gap with the starter
D. reduce eddy current losses
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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When using a megohmmeter to test insulation, good insulation will be indicated by .
A. slight kicks of the needle down scale
B. a downward dip followed by a gradual climb to the true resistance value
C. a gradual rise in the pointer reading at the outset
D. the initial dip of the pointer
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The process, whereby electrons gain sufficient energy to bereleased from the surface of a thin, heated metal plate, isknown as
.
A. photo electric emission
B. secondary emission
C. thermionic emission
D. regressive emission
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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The multiple prefix “tera” (T) means .
A. thousand (10 to the 3rd power)
B. million (10 to the 6th power)
C. billion (10 to the 9th power)
D. trillion (10 to the 12th power)
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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In a series circuit, which value will remain unchanged at all places in the circuit?
A. Voltage
B. Current
C. Resistance
D. Inductance
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Which of the listed conditions describes the effect on intrinsic semiconductor operation as a result of a temperature increase?
A. Additional heat sinks will be required
B. Conductivity will increase
C. Conductivity will decrease
D. Resistivity will increase
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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To minimize magnetic field interaction between electrical conductors in physical proximity, it is best to keep them .
A. parallel and as close as possible to each other
B. at right angles and as close as possible to each other
C. parallel to and as far as practicable from each other
D. at right angles and as far as practicable from each other
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The purpose of a motor undervoltage protection device is to
.
A. prevent high armature current when power is restored
B. start the motor at a very low voltage
C. trip the load off the motor in case of fire
D. protect personnel from low voltage shocks
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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Low voltage releases as used in some shipboard motor starter and control equipment will have which of the following characteristics?
A. They trip circuit contactors when the motor starts to overspeed.
B. They require manual resetting upon restoration of normal voltage.
C. They use a phase sensitive relay to trip contacts in series with the holding coil of the starter.
D. They allow the motor to restart upon restoration of normal voltage.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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A motor controller contains three selector push buttons labeled “start”, “jog”, and “stop”. When the “jog” button is pushed, the motor
.
A. will run continuously after the “jog” button is released
B. will run until the “jog” button is released
C. will not start until both the “jog” and “start” buttons are pushed
D. will not stop unless the “stop” button is pushed
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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78.A three-phase, induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the machine from being damaged?
A. Overspeed trip
B. Thermal overload relay
C. Three-pole safety switch
D. Magnetic blowout coil
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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- Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test as the .
A. insulation may be damaged
B. insulation may be covered with moisture
C. armature windings will have a greater number of leakage paths
D. larger machines may acquire a charge of static electricity during operation
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Most conducting materials such as copper, aluminum, iron, nickel, and tungsten .
A. increase in resistance with increased temperature
B. increase in resistance with decreased temperature
C. decrease in resistance with increased temperature
D. increase in conductance with increased temperature
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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If the pointer fails to return to zero when a megger is disconnected, the .
A. pointer is stuck
B. hair springs are burned out
C. megger is out of calibration
D. megger is operating normally
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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In electronic circuits, DC voltages can be positive (+) or negative (-) when measured with respect to the .
A. printed circuit board “common” trace
B. chassis, console frame or hull “ground”
C. analogue or digital circuitry “common” bus
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Capacitors are used on the output of the power supply in today’s consoles to .
A. filter out “ripple”
B. prevent overloads
C. act as a permanent load
D. decrease the average value of the output voltage
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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Which of the following components are used to assemble a fluorescent lighting system?
A. Lamp
B. Starter
C. Ballast
D. All of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The schematic symbol for an operational amplifier in an analog circuit is a .
A. circle
B. square
C. trapezoid
D. triangle
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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For more complete vessel protection when using an impressed current cathodic system .
A. all ship’s service alternators have additional temperature sensing
devices and a thermal recorder installed
B. machinery on deck and in the engineroom is first coated with zinc chromate before final painting
C. the hull’s magnetic fields are aligned with a solid-state degaussing circuit using SCR’s
D. straps connect the rudder with the hull and the propeller shaft is grounded through a slip ring/brush arrangement
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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When you are making a high potential test on a piece of repaired electrical machinery, a rise in leakage current indicates
.
A. good insulation
B. bad insulation
C. high insulation power factor
D. a high slot discharge factor
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Regarding an induction motor, the power developed by the rotor automatically adjusts itself to the .
A. power required to drive the load
B. speed required to drive the load
C. current flow in the motor stator
D. torque developed by the rotating field
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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Routine maintenance of dry-type transformers should include
.
A. cleaning the windings, if accessible, with a vacuum cleaner or very low pressure air
B. measuring and recording the winding temperature with an accurate mercury thermometer
C. periodic cleaning of the winding insulation with an approved solvent
D. making sure that the units are close to bulkheads or corners to protect them from damage
Ans: A
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the .
A. bridge control panel
B. disconnect links
C. governor relay box
D. main switchboard
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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A switchboard for an AC electrical system requires the use of which of the following devices?
A. Frequency meter.
B. Ohmmeter.
C. Induction voltage regulator.
D. Current transformer governor.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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- One function of the movable cams in a drum-type motor controller is to .
A. regulate the speed of the motor
B. maintain resistance contacts in clean condition
C. insulate the operating handle
D. limit the amount of load put on the motor
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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Magnetic controller contacts may become welded together during operation due to .
A. an open coil
B. low contact pressure
C. excessive ambient temperature
D. excessive magnetic gap
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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What is the function of the interpoles installed in DC motors?
A. To provide greater torque by strengthening the main field.
B. To provide sparkless commutation without having to shift the brushes.
C. To limit the production of counter-electromotive force.
D. To limit the starting surge current.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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You are testing the insulation in an AC generator with a megohmeter. The resistance value of a dry, clean winding will
.
A. continue to rise as the test potential is maintained, becoming fairly steady as the leakage current stabilizes
B. remain constant as the temperature of the windings increases
C. continue to drop as the potential is maintained, becoming fairly steady after 5 to 7 minutes
D. stabilize after approximately 2 to 4 minutes of fluctuation
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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The sub-multiple prefix “micro” (Greek letter ‘mu’) means
.
A. thousandth (10 to the -3rd power)
B. millionth (10 to the -6th power)
C. billionth (10 to the -9th power)
D. trillionth (10 to the -12th power)
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The amount of current flow required for the cathodic protection of a vessel is dependent upon the .
A. amount of bare steel surface
B. speed of the ship through the water
C. temperature of the water
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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When replacing a power transistor fitted with a heat sink in a circuit, a coating of silicone grease is applied between the transistor case and the heat sink. This is done to .
A. lubricate the transistor
B. lubricate the heat sink
C. aid in the removal of the heat sink
D. provide maximum heat transfer
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The point of operation for a saturable reactor in a power circuit is that at which .
A. a large change in control current results in small change in load current
B. a small change in load current results in a large change in control current
C. a small change in control current results in a large change in load current
D. a large change in load current causes a small change in control current
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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What precaution should be taken with a vessel’s impressed current cathodic protection system after a drydocking period during which the hull has been painted?
A. Output currents should be carefully monitored to assure operation at nearly 100 % capacity for proper curing.
B. Reference cell voltages should be maintained at half the normal range for approximately 48 hours.
C. The unit should remain off for the specified amount of time so as not
to disturb curing.
D. A slight (10-15%) overcurrent to the anodes should be allowed in order to speed drying.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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Possible phase relationships between voltage and current in an alternating current circuit include which of the following conditions?
A. Current and voltage may be in phase.
B. Current may lead the voltage.
C. Current may lag the voltage.
D. All of the above.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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Which of the procedures listed could result in damaging a transistor beyond repair?
A. Applying incorrect polarity to the collector circuit.
B. Applying excessive voltage to the input circuit.
C. Careless soldering which would overheat the transistor.
D. All of the above.
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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- If the contacts of a motor starter or controller fail to drop out when the “stop” button is depressed the .
A. contacts are carrying excessive current
B. contacts have become welded together
C. shading coil is broken
D. shading coil is loose
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an .
A. small wire brush
B. compressed air jet
C. clean dry cloth
D. 10% solution carbon solvent and water
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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Controller contacts should be routinely cleaned by .
A. blowing with compressed air
B. filing with a bastard file
C. wiping with a clean dry cloth
D. dressing with crocus cloth
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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When troubleshooting AC motors, a portable growler can be used for locating .
A. open field coils
B. grounded field coils
C. grounded stator coils
D. shorted stator coils
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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When charging a nickel-cadmium battery, .
A. the charging rate should be lessened when gassing commences
B. overcharging should be avoided
C. the specific gravity of the electrolyte will be unaffected by the state of charge
D. add distilled water just prior to charging to insure proper mixing
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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Which of the listed items will stop a motor due to a reduction in voltage and restart it when the voltage is restored to normal?
A. Low voltage protection circuit
B. Non-renewable link fuse
C. Renewable link fuse
D. Low voltage release circuit
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The difference between the synchronous speed of an induction machine and its operating speed (slip) may be correctly expressed
.
A. as a percent of synchronous speed
B. as a decimal fraction of synchronous speed
C. directly in revolutions per minute
D. as all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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A suspected “open” in a motor field can be tested by using a/an
.
A. potentiometer
B. megger
C. wattmeter
D. ammeter
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Basically, a magnetic amplifier is a saturable reactor withthe addition of .
A. AC to the bias winding
B. variable capacitance to all windings
C. eddy current protectors
D. a rectifier in the load circuit
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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A capacitor discolored due to excessive heat should be
.
A. calibrated
B. replaced
C. cooled
D. soldered
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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A ground in an electrical circuit outside the engine room
.
A. cannot be detected under normal conditions
B. is of no consequence to engineering personnel
C. is indicated at the branch circuit breaker panel
D. is indicated by the ground detecting lamps on the main switchboard
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]D
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The third color band on a resistor is used to indicate the
.
A. tolerance of the resistor
B. number of zeros following the first two significant figures in the resistance value
C. first significant figure of the resistance
D. second significant figure of the resistance
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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Impressed current cathodic protection is used on vessels instead of
.
A. fire alarm systems
B. repeated painting
C. sacrificial zincs
D. vacuum tube degaussing systems
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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Common basic applications for the operational amplifier include
.
A. counting, pulsing and clocking amplifiers
B. summing, scaling and difference amplifiers
C. step-up, step-down and rectifying amplifiers
D. all of the above
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]B
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The timer element found in a reverse power relay obtains its operating torque via .
A. line voltage
B. the main bus
C. electromagnets
D. a separate battery source
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]C
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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 .
A. reduces magnetic force on the plunger and requires more current to trip the relay
B. reduces magnetic force on the plunger and requires less current to trip the relay
C. increases magnetic force on the plunger and requires more current
to trip the relay
D. increases magnetic force on the plunger and requires less current to trip the relay
[bg_collapse view=”button-orange” color=”#49494a” expand_text=”View Answer” collapse_text=”Hide Answer” ]A
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