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competency Quiz on c05b, created by mrk nthny on 15/08/2016.

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Questão 1 de 149

1

Reversing the DC current flow through an electrical coil will _____.

Selecione uma das seguintes:

  • reverse its two-pole field

  • reduce the amount of flux produced

  • change its impedance

  • reduce the power consumed

Explicação

Questão 2 de 149

1

A device which prints out a permanent record of the plant operating conditions is known as the _________.

Selecione uma das seguintes:

  • data logger

  • analogger

  • bell logger

  • alarm logger

Explicação

Questão 3 de 149

1

Engine room watch officers should keep a constant check on the loads carried by electric motors because _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 4 de 149

1

The torque produced by a motor when the shaft will not turn, even though rated voltage is applied to the stator, is known as ___.

Selecione uma das seguintes:

  • locked rotor torque

  • pullout torques

  • breakdown torque

  • torque margin

Explicação

Questão 5 de 149

1

An operating characteristic appearing on the name plates of shipboard AC motors is____.

Selecione uma das seguintes:

  • Temperature rise

  • type of overload protection

  • rated slip

  • locked rotor torque

Explicação

Questão 6 de 149

1

Which of the following operating characteristics for DC motors is considered to give high starting torque?

Selecione uma das seguintes:

  • series

  • shunt

  • cumulative-compound

  • differential-compound

Explicação

Questão 7 de 149

1

What type of electric motor is commonly used to start small auxiliary diesel engines?

Selecione uma das seguintes:

  • series

  • synchronous

  • cage

  • shunt

Explicação

Questão 8 de 149

1

In a compound-wound motor, a portion of the line current flows through the ____.

Selecione uma das seguintes:

  • shunt field coils

  • inertia poles

  • stator

  • frame

Explicação

Questão 9 de 149

1

An advantage of DC motors over AC motors is that they ______.

Selecione uma das seguintes:

  • offer infinite speed variations

  • are less expensive

  • require less maintenance

  • offer slow speed

Explicação

Questão 10 de 149

1

The cycle per second developed by the alternator aboard your vessel is determined by ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 11 de 149

1

One important difference between wye-connected and delta-connected generators is that delta connections have ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 12 de 149

1

A DC generator which is used to supply direct current in order to maintain an AC generator field is commonly known as a/an ______.

Selecione uma das seguintes:

  • exciter

  • rotor

  • stator

  • armature

Explicação

Questão 13 de 149

1

DC generator circuits are protected against malfunctions due to prime mover power loss by the use of ____

Selecione uma das seguintes:

  • reverse current relays

  • main bus disconnect links

  • a separate battery back-up

  • reverse power relays

Explicação

Questão 14 de 149

1

Armature cores in a DC generator are made of laminated steel sheets to ___.

Selecione uma das seguintes:

  • reduce eddy current losses

  • fit the curvature of the frame

  • increase the hysteresis effect

  • allow for easy assembly

Explicação

Questão 15 de 149

1

Modern DC generators are fitted with commutating poles to ____.

Selecione uma das seguintes:

  • reduce sparking

  • prevent motorizing

  • reduce spring pressures ion the brushes

  • reduce the load on the main poles

Explicação

Questão 16 de 149

1

The simplest method of controlling the terminal voltage of compound-wound DC generator is with a ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 17 de 149

1

Which of the terms listed best describes a compound wound DC generator having a higher voltage at no load than at full load?

Selecione uma das seguintes:

  • Under compound

  • Flat compound

  • Over compound

  • Terminal compound

Explicação

Questão 18 de 149

1

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

Selecione uma das seguintes:

  • I, II and III

  • I only

  • I and II only

  • II and III only

Explicação

Questão 19 de 149

1

Regarding an induction motor, the output power developed is related to the ____.

Selecione uma das seguintes:

  • slip of the rotor

  • speed of the rotating field

  • DC filed excitation

  • current flow in the interpoles

Explicação

Questão 20 de 149

1

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 ___.

Selecione uma das seguintes:

  • a percent of synchronous speed

  • the reduced amp rating

  • the decrease in shaft torque

  • reduced fuel consumption

Explicação

Questão 21 de 149

1

The speed of a squirrel cage induction motor is determined by the ____.

Selecione uma das seguintes:

  • number of the stator poles

  • diameter of the stator

  • bar resistance of the conducting rotor

  • motor winding resistance

Explicação

Questão 22 de 149

1

The most practical method of controlling the RPM of a step-speed AC motor is to ____..

Selecione uma das seguintes:

  • vary the number of poles

  • change input voltage

  • change the number of brushes

  • vary power factor

Explicação

Questão 23 de 149

1

Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine ____.

Selecione uma das seguintes:

  • slightly greater than the line frequency

  • slightly less than the line frequency

  • the same as the line frequency

  • greater than the line frequency

Explicação

Questão 24 de 149

1

The division of kilowatt load between two paralleled alternators is determined by the ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 25 de 149

1

The load sharing characteristics of two diesel alternators operating in parallel are directly related to the setting of their governors’_____.

Selecione uma das seguintes:

  • speed droop

  • Load limit

  • idle speed

  • speed limit

Explicação

Questão 26 de 149

1

Kilowatt load is divided between two AC generators operating in parallel by ____.

Selecione uma das seguintes:

  • adjusting the governor controls

  • varying the excitation voltage

  • increasing both prime mover speeds simultaneously

  • decreasing both prime mover speeds simultaneously

Explicação

Questão 27 de 149

1

The division of the reactive KVA load between paralleled AC generators is initiated by the ____.

Selecione uma das seguintes:

  • voltage regulators

  • prime mover governors

  • proportioner

  • phase balance relay

Explicação

Questão 28 de 149

1

After closing the circuit breaker to place tow similar alternators in parallel, the NEXT step is to balance the _____.

Selecione uma das seguintes:

  • kilowatt load

  • power factor

  • voltage load

  • ampere load

Explicação

Questão 29 de 149

1

If the energy input is significantly reduced to the prime mover of one ship board alternator operating in parallel with others, that alternator will ___.

Selecione uma das seguintes:

  • 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

Explicação

Questão 30 de 149

1

When two AC generators are being paralleled, the breaker should be closed with the synchroscope pointer rotating in ____.

Selecione uma das seguintes:

  • ‘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

Explicação

Questão 31 de 149

1

A change in field excitation of an alternator operating in parallel will cause a change in its _____________.

Selecione uma das seguintes:

  • voltage output

  • alternator frequency

  • kilowatt load

  • current rating

Explicação

Questão 32 de 149

1

The purpose of squirrel-cage windings in a synchronous motor is to ___.

Selecione uma das seguintes:

  • provide a means for starting

  • provide more precise balancing

  • produce a higher power factor

  • eliminate arcing between the stator and the frame

Explicação

Questão 33 de 149

1

Amortisseur windings are installed in a synchronous motor to ___.

Selecione uma das seguintes:

  • provide a means for starting

  • reduce eddy current losses

  • produce a higher power factor

  • eliminate arcing between the stator and the rotor

Explicação

Questão 34 de 149

1

A common source of field excitation for synchronous motors is a/an ______.

Selecione uma das seguintes:

  • DC rectifier

  • low voltage battery

  • motor attenuator set

  • AC supply

Explicação

Questão 35 de 149

1

An increase in which of the listed conditions will increase the speed of synchronous electric motor?

Selecione uma das seguintes:

  • Frequency

  • Voltage

  • Armature current

  • Inductance

Explicação

Questão 36 de 149

1

The speed of a synchronous motor is varied by ____.

Selecione uma das seguintes:

  • changing the input frequency

  • interchanging any tow of the three live leads

  • changing the voltage of the system

  • increasing the field excitation

Explicação

Questão 37 de 149

1

What is the approximate voltage per cell produced by the nickel-iron (Edison) battery?

Selecione uma das seguintes:

  • 1.35 volts

  • 0.85 volts

  • 6.05 volts

  • 2.20 volts

Explicação

Questão 38 de 149

1

Common nickel-cadmium and nickel-iron storage batteries utilize _____.

Selecione uma das seguintes:

  • alkaline secondary cells

  • acid primary cells

  • alkaline primary cells

  • acid secondary cells

Explicação

Questão 39 de 149

1

What is the approximate discharge voltage produced by one cell of a wet type nickel-cadmium battery?

Selecione uma das seguintes:

  • 1.25 volts

  • 1.5 volts

  • 2.2 volts

  • 6.0 volts

Explicação

Questão 40 de 149

1

The capacity of a storage battery is measured in ____.

Selecione uma das seguintes:

  • ampere-hours

  • volts

  • volt-hours

Explicação

Questão 41 de 149

1

Local action in a dry-cell, or lead storage battery is the process whereby ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 42 de 149

1

When mixing electrolyte, which if the following precautions should always be observed?

Selecione uma das seguintes:

  • Add the acid to the water

  • Use a heavy duty aluminum pail

  • Add the water to the acid

  • Mix the solution outdoors

Explicação

Questão 43 de 149

1

The normal open-circuit voltage of one cell of a fully charged lead-acid battery is ____.

Selecione uma das seguintes:

  • 2 volts

  • 1.5 volts

  • 12 volts

  • 6 volts

Explicação

Questão 44 de 149

1

When lead-acid batteries are charging, they always give off hydrogen gas that is ____.

Selecione uma das seguintes:

  • highly explosive

  • considered inert

  • heavier than air

  • extremely toxic

Explicação

Questão 45 de 149

1

When charging lead-acid batteries the charging rate should be reduced as the battery nears its full charge to ____.

Selecione uma das seguintes:

  • prevent damaging battery plates

  • allow equalization of cell voltages

  • reduce lead sulfate deposits

  • increase lead peroxide formation

Explicação

Questão 46 de 149

1

When a lead-acid battery gassing freely while receiving a normal charge, the charging current should be ____.

Selecione uma das seguintes:

  • decreased

  • increased

  • shut off

  • unchanged

Explicação

Questão 47 de 149

1

Violent gassing developed by a lead-acid battery during charging indicates that the ____.

Selecione uma das seguintes:

  • charging rate is excessive

  • plate separators are grounded

  • cell voltages are excessive

  • specific gravity is insufficient

Explicação

Questão 48 de 149

1

A nickel-cadmium battery is receiving a normal charge and gases freely. The charging current should ____.

Selecione uma das seguintes:

  • remain the same

  • be decreased

  • be cut off and the battery allowed to cool

  • be increased

Explicação

Questão 49 de 149

1

Battery charging rooms should be well ventilated because the charging process produces ____.

Selecione uma das seguintes:

  • explosive gases

  • highly combustible oxygen

  • highly poisonous gas

  • corrosive gases

Explicação

Questão 50 de 149

1

Protection against sustained overloads occurring in molded-case circuit breakers is provided by a/an ____.

Selecione uma das seguintes:

  • thermal acting trip

  • overvoltage release

  • reverse current relay

  • low voltage relay

Explicação

Questão 51 de 149

1

The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 52 de 149

1

Electrical circuits are protected against overheating by means of a/an ___.

Selecione uma das seguintes:

  • circuit breaker

  • amplifier

  • diode

  • capacitor

Explicação

Questão 53 de 149

1

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

Selecione uma das seguintes:

  • I, II and III

  • I only

  • I and II only

  • II and III only

Explicação

Questão 54 de 149

1

As storage battery for an emergency lighting and power system must have the capacity to ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 55 de 149

1

Regulations require emergency diesel engine starting systems to have sufficient capacity to provide power for at least ____.

Selecione uma das seguintes:

  • six consecutive cranking cycles

  • three continuous starting sequences

  • nine repeated starts under load

  • twelve cranking periods of 5 seconds

Explicação

Questão 56 de 149

1

The source of emergency lighting and power at loss of normal ship’s power on a cargo vessel should be obtained from the ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 57 de 149

1

An emergency generator driven by an internal combustion engine, shall be tested under load for a minimum of 2 hours at least once evry ___.

Selecione uma das seguintes:

  • month

  • 2 weeks

  • week

  • 3 months

Explicação

Questão 58 de 149

1

A bus disconnect link is used to isolate ___.

Selecione uma das seguintes:

  • 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

Explicação

Questão 59 de 149

1

A ‘dead front’ switchboard is one ____.

Selecione uma das seguintes:

  • with insulated switches and no exposed terminals

  • without switches on it

  • without circuit breakers

  • without safety hand rail nor rubber mats

Explicação

Questão 60 de 149

1

Which of the following statements identifies the difference between the primary windings and the secondary windings of a 2:1 step down transformer?

Selecione uma das seguintes:

  • 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

Explicação

Questão 61 de 149

1

Increasing the load on the secondary windings of a transformer will cause a/an _____.

Selecione uma das seguintes:

  • increase in the primary current

  • decrease in the primary voltage

  • increase in the primary voltage

  • decrease in the primary current

Explicação

Questão 62 de 149

1

Power transformers are rated in _____.

Selecione uma das seguintes:

  • kilovoltamperes

  • kilowatt-amps

  • ampere-turns

  • kilowatt-volts

Explicação

Questão 63 de 149

1

Relative to the secondary winding of a step-up transformer, the primary winding will have ____.

Selecione uma das seguintes:

  • fewer turns

  • more turns

  • same number of turns but smaller wires

  • twice as many turns

Explicação

Questão 64 de 149

1

When a transformer is used to step-down voltage, the low voltage winding is ___.

Selecione uma das seguintes:

  • the secondary coil

  • part of the core

  • the primary coil

  • not insulated

Explicação

Questão 65 de 149

1

In a three-phase, open-delta connected transformer, the line current is equal to ____.

Selecione uma das seguintes:

  • the phase current

  • three times the phase current

  • the sum of any two phase currents

  • the difference of any two phase currents

Explicação

Questão 66 de 149

1

Transformers are used onboard ships with AC generators to ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 67 de 149

1

Which of the listed transformers uses a single winding to produce voltage transformation?

Selecione uma das seguintes:

  • Autotransformers

  • Stepup transformers

  • Stepdown transformers

  • Isolation transformers

Explicação

Questão 68 de 149

1

A transformer works on the basic principle of ____.

Selecione uma das seguintes:

  • mutual induction

  • self impedance

  • attraction and repulsion

  • increasing power

Explicação

Questão 69 de 149

1

The basic operating principle of a transformer is attributed to ___.

Selecione uma das seguintes:

  • electromagnetic induction

  • variance of a conductor in a magnetic fluid

  • mutual reaction

  • thermionic emission

Explicação

Questão 70 de 149

1

If a transformer is connected to a DC source, the transformer will overload at the _____.

Selecione uma das seguintes:

  • primary coil

  • contacts

  • secondary coil

  • core

Explicação

Questão 71 de 149

1

Transformer cores are laminated to reduce ____.

Selecione uma das seguintes:

  • eddy currents

  • secondary flux

  • leakage flux

  • tertiary flux

Explicação

Questão 72 de 149

1

A transformer in an electric circuit serves to ___.

Selecione uma das seguintes:

  • increase or decrease circuit voltage as required

  • generate its own electrical power

  • transform electrical energy into mechanical energy

  • convert AC current to DC current

Explicação

Questão 73 de 149

1

In an alternating current electrical system, a low system power factor is a direct sign of ____.

Selecione uma das seguintes:

  • a large inductive load

  • a large resistance load

  • a short in exciter field windings

  • a ground in exciter field windings

Explicação

Questão 74 de 149

1

Voltage will always lead current in a/an_____.

Selecione uma das seguintes:

  • inductive circuit

  • capacitive circuit

  • magnetic circuit

  • resistive circuit

Explicação

Questão 75 de 149

1

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 _____.

Selecione uma das seguintes:

  • unity

  • lagging

  • leading

  • infinity

Explicação

Questão 76 de 149

1

When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is ___.

Selecione uma das seguintes:

  • maximum

  • lagging

  • leading

  • minimum

Explicação

Questão 77 de 149

1

Capacitors can be used in electric distribution systems to improve power factor. This is accomplished by seesawing energy between the capacitor and the ____.

Selecione uma das seguintes:

  • inductive loads

  • generator

  • resistive loads

  • transformer

Explicação

Questão 78 de 149

1

Which of the following types of motors can be used for correcting power factor during normal operation?

Selecione uma das seguintes:

  • Synchronous

  • Polyphase

  • Wound-rotor

  • Induction

Explicação

Questão 79 de 149

1

Which of the substances listed can be used to shield sensitive equipment from static magnetic fields?

Selecione uma das seguintes:

  • Permeable Iron

  • Glass

  • Mica

  • Bakelite

Explicação

Questão 80 de 149

1

The purpose of a magnetic relay is to ______.

Selecione uma das seguintes:

  • remotely open and close contacts

  • open a circuit only in the event of overload

  • provide overcurrent protection during starting

  • relay voltages at increased power

Explicação

Questão 81 de 149

1

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

Selecione uma das seguintes:

  • I, II and III

  • I only

  • I and II only

  • II and III only

Explicação

Questão 82 de 149

1

An adjustable resistor, whose resistance can be changed without opening the circuit in which it is connected, is called a ____.

Selecione uma das seguintes:

  • rheostat

  • bleeder resistor

  • bridge

  • variable shunt strip

Explicação

Questão 83 de 149

1

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 _____.

Selecione uma das seguintes:

  • 4.9 and 5.1 milliamperes

  • 4.8 and 5.2 milliamperes

  • 4.5 and 5.5 milliamperes

  • 4.0 and 6.0 milliamperes

Explicação

Questão 84 de 149

1

A DC ammeter would normally be connected ______.

Selecione uma das seguintes:

  • in series with a circuit

  • in parallel with a circuit

  • with internal shunts only

  • without regard to polarity

Explicação

Questão 85 de 149

1

If the approximate voltage to be measured in an electric circuit is not known, you should _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 86 de 149

1

The resistance value of a resistor in a circuit can best be determined by the ______.

Selecione uma das seguintes:

  • band markings on the resistor

  • single solid body color of the resistor

  • amperage value written on the resistor

  • physical size of the resistor

Explicação

Questão 87 de 149

1

The basic “control action” of a magnetic amplifier is dependent upon _____.

Selecione uma das seguintes:

  • variations in the load capacities

  • changes in the inductance

  • the type of core material

  • the construction of the core

Explicação

Questão 88 de 149

1

A general purpose electrical multimeter can be used to directly measure ____.

Selecione uma das seguintes:

  • current

  • watts

  • field flux

  • all of the above

Explicação

Questão 89 de 149

1

The Wheatstone bridge is a precision measuring instrument utilizing the principle of changes in ____.

Selecione uma das seguintes:

  • resistance

  • inductance

  • capacitance

  • amperage

Explicação

Questão 90 de 149

1

The RPM of an AC generator can be measured with a/an _____.

Selecione uma das seguintes:

  • vibrating reed meter

  • ammeter

  • voltmeter

  • synchroscope

Explicação

Questão 91 de 149

1

The shunt of a DC ammeter should be connected in _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 92 de 149

1

Which of the following statements represents the correct method of connecting the shunt of an ammeter prior to taking a reading?

Selecione uma das seguintes:

  • 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

Explicação

Questão 93 de 149

1

Which of the following meters uses a shunt connected in series with the load, but parallel with the meter movement?

Selecione uma das seguintes:

  • ammeter

  • voltmeter

  • power factor meter

  • wattmeter

Explicação

Questão 94 de 149

1

External shunts are sometimes used with ammeters to _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 95 de 149

1

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 _____.

Selecione uma das seguintes:

  • 9.8 and 10.2 milliamperes

  • 9.8 and 10.0 milliamperes

  • 8.0 and 12.0 milliamperes

  • 8.0 and 10.0 milliamperes

Explicação

Questão 96 de 149

1

An ammeter reads slightly ‘zero’ when its lead are disconnected, this is a result of ______.

Selecione uma das seguintes:

  • mechanical misalignment of the meter pointer

  • a poor ground for the meter case

  • static electricity in the air

  • resistor inside the meter storing charges

Explicação

Questão 97 de 149

1

When a resistor is used as a shunt and is connected in parallel with a meter movement coil, it will provide _____.

Selecione uma das seguintes:

  • an extended meter range

  • a measurement of circuit resistance

  • an increased accuracy of approximately 1.5 percent

  • none of the above

Explicação

Questão 98 de 149

1

A galvanometer is an instrument used to measure ____.

Selecione uma das seguintes:

  • very small amounts of current or voltage

  • thickness of galvanized metal

  • resistance of electrical wiring insulation

  • quantity of galvans in an electric circuit

Explicação

Questão 99 de 149

1

To limit the current flow through a DC, voltmeter to as low a value as possible, the moving coil is provided with a/an ____.

Selecione uma das seguintes:

  • high series resistance

  • high parallel resistance

  • series inductor

  • external shunt

Explicação

Questão 100 de 149

1

AC voltmeters are generally calibrated to read the ____.

Selecione uma das seguintes:

  • RMS voltage

  • instantaneous voltage

  • average voltage

  • peak voltage

Explicação

Questão 101 de 149

1

Most AC voltmeters are calibrated to indicate ____.

Selecione uma das seguintes:

  • root-mean-square voltage

  • peak-to-peak voltage

  • average voltage

  • peak voltage only

Explicação

Questão 102 de 149

1

Conductor resistance may be INDIRECTLY measured by using a/an______.

Selecione uma das seguintes:

  • voltmeter and an ammeter

  • voltmeter only

  • ammeter only

  • frequency meter

Explicação

Questão 103 de 149

1

Which of the following statements regarding the use of a current measuring instrument is correct ?

Selecione uma das seguintes:

  • 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

Explicação

Questão 104 de 149

1

Handheld electrical phase sequence indicators are useful when ____.

Selecione uma das seguintes:

  • connecting shore power lines to the ship

  • preparing to parallel alternators

  • connecting lighting branch circuits

  • troubleshooting DC motors

Explicação

Questão 105 de 149

1

Modern handheld non-contact digital tachometers operate by counting light pulses returned to the unit by _____.

Selecione uma das seguintes:

  • a piece of reflective tape mounted in the shaft

  • the vibrating tach generator

  • the coupling bolts

  • a small bulb attached to the shaft

Explicação

Questão 106 de 149

1

A handheld reflective digital tachometer could give a false reading it ____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 107 de 149

1

Electrostatic forces in high voltage circuits cause indicating instruments to give ____.

Selecione uma das seguintes:

  • inaccurate readings

  • parallax readings

  • highly intuitive readings

  • highly accurate readings

Explicação

Questão 108 de 149

1

Fuses are usually rated in ___.

Selecione uma das seguintes:

  • amps and volts

  • watts

  • volts only

  • amps only

Explicação

Questão 109 de 149

1

Time delayed or delayed action-type fuses are designed to ___.

Selecione uma das seguintes:

  • permit momentary overloads without melting

  • prevent grounds in branch circuits

  • prevent opens in motor circuits

  • guard lighting and electronic circuits

Explicação

Questão 110 de 149

1

In a cartridge-type fuse, the metal element is contained in a ____.

Selecione uma das seguintes:

  • fiber tube

  • porcelain window

  • thermal cut out

  • flasher device

Explicação

Questão 111 de 149

1

Fuses placed in series with a thermal trip-type circuit breaker are used for ____.

Selecione uma das seguintes:

  • short-circuit protection

  • time-delay protection

  • short duration surge protection

  • sustained overload protection

Explicação

Questão 112 de 149

1

The energy consumed by AC motor, as strictly reactive power, is _____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 113 de 149

1

A constant output voltage from an AC generator is maintained by the ___.

Selecione uma das seguintes:

  • voltage regulator

  • prime mover governor

  • exciter generator

  • reverse power relay

Explicação

Questão 114 de 149

1

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 ____.

Selecione uma das seguintes:

  • dip

  • droop

  • drop

  • regulation

Explicação

Questão 115 de 149

1

Prior to starting an AC generator prime mover, the voltage regulator selector switch should be placed in the ___.

Selecione uma das seguintes:

  • manual position

  • bus neutral position

  • raise voltage position

  • transfer position

Explicação

Questão 116 de 149

1

Which is a function of the voltage regulators used with AC generators?

Selecione uma das seguintes:

  • 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

Explicação

Questão 117 de 149

1

The life expectancy of electrical insulation, is approximately hal;ved for an increased operating temperature of ___.

Selecione uma das seguintes:

  • 10ºC

  • 25ºC

  • 50ºC

  • 100ºC

Explicação

Questão 118 de 149

1

If a pointer on a megger fails to return to ‘zero’ when not being used, the ____.

Selecione uma das seguintes:

  • megger is operating normally

  • megger is out of calibration

  • hairsprings are burned out

  • pointer probably stuck in that position

Explicação

Questão 119 de 149

1

A multimeter may be damaged by taking a ___.

Selecione uma das seguintes:

  • 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

Explicação

Questão 120 de 149

1

In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This accomplished by opening the ___.

Selecione uma das seguintes:

  • bus disconnect link

  • reverse power relay

  • generator bus fuse connections

  • power directional relay

Explicação

Questão 121 de 149

1

When replacing fuses, always make sure ___.

Selecione uma das seguintes:

  • 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’

Explicação

Questão 122 de 149

1

When working on electrical circuits containing large capacitors, in addition to de-energizing the circuit, which of the listed precaution should also be taken?

Selecione uma das seguintes:

  • Ground the capacitor terminals

  • keep all radio equipment away

  • Measure capacitor insulation resistance

  • Check capacitor circuit polarity

Explicação

Questão 123 de 149

1

The third color band on a resistor is used to indicate the_______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 124 de 149

1

Which of the listed conditions describes the effect on intrinsic semiconductor operation as a result of a temperature increase?

Selecione uma das seguintes:

  • Conductivity will increase

  • Capacitive reactance will decrease

  • Inductive reactance will decrease

  • Resistivity will increase

Explicação

Questão 125 de 149

1

A signal derived from a controlled function and returned to the initiating point is called a/an_____.

Selecione uma das seguintes:

  • feedback signal

  • monitoring signal

  • inverse signal

  • reverse signal

Explicação

Questão 126 de 149

1

Which of the following statements describes the significance of ambient temperature in relation to the service life of electronic components?

Selecione uma das seguintes:

  • 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.

Explicação

Questão 127 de 149

1

The method used to produce electron emission in most vacuum tubes is known as______.

Selecione uma das seguintes:

  • thermionic emission

  • photoelectric emission

  • secondary electric emission

  • cold cathodic electric emission

Explicação

Questão 128 de 149

1

In electronic circuitry, the abbreviation 'PCB' commonly means________.

Selecione uma das seguintes:

  • printed circuit board

  • pulse coded binary

  • poly -coated braid

  • personal computer bits

Explicação

Questão 129 de 149

1

Which of the following statements concerning analog and digital devices are correct?

Selecione uma das seguintes:

  • 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.

Explicação

Questão 130 de 149

1

Which of the following statements correctly applies to transistors?

Selecione uma das seguintes:

  • 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.

Explicação

Questão 131 de 149

1

A silicon controlled rectifier (SCR) is a solid state device used to change_______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 132 de 149

1

Silicon diodes which are designed for a specific reverse breakdown voltage, and are most often used in electronic power supply voltage regulators, are called________.

Selecione uma das seguintes:

  • Zener diodes

  • tunnel diodes

  • hot -carrier diodes

  • compensating diodes

Explicação

Questão 133 de 149

1

Which of the listed devices may be used as a digital device?

Selecione uma das seguintes:

  • diode

  • variable resistor

  • strain gauge

  • thermistor

Explicação

Questão 134 de 149

1

A triac thyristor functions as a control device and basically functions as______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 135 de 149

1

The purpose of a heat sink, as frequently used with transistors, is to______.

Selecione uma das seguintes:

  • prevent excessive temperature rise

  • compensate for excessive doping

  • increase the reverse current

  • decrease the forward current

Explicação

Questão 136 de 149

1

In process control terminology, continuously variable values which change without distinct increments, such as temperature, pressure, or level are called_______.

Selecione uma das seguintes:

  • analog values

  • binary values

  • digital values

  • bumpless values

Explicação

Questão 137 de 149

1

Increasing the power source frequency in a capacitive circuit will_____.

Selecione uma das seguintes:

  • 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

Explicação

Questão 138 de 149

1

An operational amplifier, as used in today's consoles, may have a calculated gain of 5. This means that as the input changes by______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 139 de 149

1

An operational amplifier, as used in today's consoles, has a calculated gain of 5. This means that when the input changes______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 140 de 149

1

Heat sinks are most frequently used with_____.

Selecione uma das seguintes:

  • power transistors

  • vacuum tubes

  • LED's

  • LCD's

Explicação

Questão 141 de 149

1

Which of the listed conditions is an advantage of a PN diode over a vacuum diode?

Selecione uma das seguintes:

  • All of the above.

  • Smaller size.

  • No warm up time.

  • More reliable.

Explicação

Questão 142 de 149

1

The schematic symbol for an operational amplifier in an analog circuit is a______.

Selecione uma das seguintes:

  • triangle

  • circle

  • square

  • trapezoid

Explicação

Questão 143 de 149

1

Which of the listed conditions is an advantage of a PN diode over a vacuum diode?

Selecione uma das seguintes:

  • All of the above.

  • Longer life.

  • No warm up time.

  • Less delicate.

Explicação

Questão 144 de 149

1

In a logic circuit, the NOT gate function______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 145 de 149

1

How many possible states does a binary logic circuit have?

Selecione uma das seguintes:

  • Two

  • One

  • Three

  • Four

Explicação

Questão 146 de 149

1

In a logic circuit the NOR and NAND gate functions______.

Selecione uma das seguintes:

  • 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

Explicação

Questão 147 de 149

1

Which of the listed logic gates is considered to be a BASIC building block (basic logic gate) used in logic diagrams?

Selecione uma das seguintes:

  • OR

  • NAND

  • NOR

  • All of the above.

Explicação

Questão 148 de 149

1

In a diesel electric plant, raising the AC generator's field excitation will cause the DC propulsion motor to______.

Selecione uma das seguintes:

  • increase in speed

  • decrease in speed

  • operate with a lower power factor

  • operate with a higher power factor

Explicação

Questão 149 de 149

1

Equipment for dc propulsion drive systems usually includes_________.

Selecione uma das seguintes:

  • 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

Explicação