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  • 問題数 89 • 7/30/2024

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    問題一覧

  • 1

    In a circuit that is not energized, which of the listed instruments is used?

    ohmmeter

  • 2

    At a point is equal to thr negative potential gradient at that point

    electric intensity

  • 3

    If a DC generator was rotated in the wrong direction it would fail to come up to voltage because the

    armature field would oppose the field current

  • 4

    A cycloconverter (CCV) is a static power converter that

    provides adjustable frequency to power an ac propulsion drive motor

  • 5

    Which of the following statement is true concerning all three-phase alternators?

    Each has three separate but identical armature windings acted on by one system of rotating magnets

  • 6

    Which of the instruments listed is used to check insulation resistance?

    megohmmeter

  • 7

    The division of kilowatt load between two paralleled alternators is determine by the

    load-speed characteristics of the governors

  • 8

    To locate a grounded field coil in a synchronous motor, which of the instruments listed could be used?

    megohmeter

  • 9

    Which of the following is non-linear circuit parameter

    inductance

  • 10

    The timer element found in a reverse power relay obtains it operating torque via

    a separate battery source

  • 11

    Which of the following statements is true concerning the operating characteristics of a squirrel-cage motor?

    Rotor slip is dependent upon the motor load

  • 12

    Protection against prolonged overload periods in a molded-case circuit breaker is provided by

    thermal relay trip

  • 13

    The type of feature afforded to auxiliaries vital to the operation of propelling equipment, where automatic restart after a voltage failure would not create hazard, which of the following termed is used to describe the process?

    low voltage release

  • 14

    The co-efficient of coupling between two air core coils depends on

    mutual inductance and self inductance of two coils

  • 15

    A material for good magnetic memory should have

    high retentivity

  • 16

    Which of the following is not provided in a switchboard for an AC electrical distribution system?

    transducer

  • 17

    The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as

    self-inductance

  • 18

    The unit of apparent power in a purely inductive circuit is called

    VAR

  • 19

    Electric intensity at any point in an electric field is equal to the at that point

    potential gradient

  • 20

    The type of feature afforded to auxiliaries vital to the operation of propelling equipment, where automatic restart after a voltage failure would not create a hazard, which of the following termed is used to describe the process?

    low voltage release

  • 21

    Which circuit element(s) will oppose the change in circuit current

    resistance only

  • 22

    A saturable-core reactor operates on the principle of controlling a load windings inductance by varying the core s

    permeability

  • 23

    The combined effect of inductive reactance, capacitive reactance, and resistance in an AC series circuit is known as

    impedance

  • 24

    Line losses in a distribution circuit are kept to a minimum by

    Using higher voltage and lower current

  • 25

    A pure transducer utilizes?

    proportion action

  • 26

    The timer element found in a reverse power relay obtains it operating torque via

    a separate battery source

  • 27

    The unit of magnetic flux is

    weber

  • 28

    The feed pumps are started/stopped manually from control panel or from the electric starter cabinet. However, when initiating start of the first main power pack, of the feed pumps will automatically be started (high capacity mode) before the power pack is started.

    two

  • 29

    Silicon steel is used in electrical machines because it has

    low hysteresis loss

  • 30

    Which solid AWG wire size has the smallest physical cross-sectional area?

    18

  • 31

    What system supplies air primarily to the combustion control system and other pneumatic controllers

    control air system

  • 32

    The frequency of an AC generator if the load is removed?

    governor control of the diesel engine driving the AC gemerator

  • 33

    When a megohmmeter is used to test insulation, the gradual rise of the point reading as a result of continued cranking is caused by

    The dielectric absorption effect of the insulation

  • 34

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

    Increased ambient temperature decreases the service life of electronic components.

  • 35

    The freezing point of electrolyte in a fully charged lead-acid battery will be

    lower than in a discharged battery

  • 36

    What is an important factor in reducing DC motor commutator wear?

    Establishing the copper oxide surface film

  • 37

    An ideal voltage source should have

    zero source resistance

  • 38

    System pressure is set by the potentiometer on the control panel, as a voltage input to the PLC. The PLC output is amplified by a proportional card controlling the proportional pressure control valve for the system pressure. The set pressure is automatically set to zero until one of the power packs has been loaded.

    valve driver

  • 39

    The power packs are started/stopped manually from control panel or from the electric starter cabinet. The power packs can be started in any sequence. . Maximum 2 following starts can be made, then minutes between each. The starts are controlled by the PLC, including starts from the electric starter cabinet.

    15

  • 40

    An air blower driven by an electric motor used to supply pressurized air into the combustion chamber is called

    Draft fan

  • 41

    What do you call a direct current passing through a wire coiled around a soft iron core?

    electromagnet

  • 42

    The power packs are started/stopped manually from control panel or from the electric starter cabinet. The power packs can be started in any sequence. Maximum starts should be made during an hour.

    4

  • 43

    Alternating current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in

    henrys

  • 44

    On tank vessel with an electrically driven capstan the motor should be meggered periodically to test

    Insulation resistance

  • 45

    Which component when defective will not produce DC voltage in the excitation system of an AC generator?

    silicon rectifier

  • 46

    Which of the following devices should be used to measure the temperature of a battery electrolyte?

    Alcohol thermometer

  • 47

    Which of the following is non-linear circuit parameter?

    inductance

  • 48

    Conductivity is analogous to

    permeability

  • 49

    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.

    increases magnetic pull on the plunger and requires less current to trip the relay

  • 50

    The control system pneumatic actuators can be mounted in the ballast tanks and adjusted with no need foe electricity, thus offering a lower-cost control approach

    marex valve

  • 51

    Which of the following problems will most likely occur if the starting winding of a split-phase induction motor failed to cutout once the motor was in continuous operation?

    the winding will burn out

  • 52

    Which of the following statements concerning the specific gravity of a battery electrolyte is true?

    The specific gravity reading is lowered when the electrolyte temperature has increased

  • 53

    In a series circuit which value will remain unchange at all places in the circuit?

    current

  • 54

    Which of the following circuit elements will oppose the change in circuit current?

    inductance

  • 55

    When a megohmmeter is used to test the winding insulation of a large motor, an initial dip of the pointer toward zero is caused by

    the capacitance of the winding

  • 56

    Which of the listed devices is used to measure and convert it to an electrical signal?

    transducer

  • 57

    Germanium semiconductor diodes are commonly used as

    retifiers

  • 58

    What does the output voltage of a three-phase alternator regulates

    DC voltage to the field

  • 59

    A capacitor is generally a

    linear and bilateral component

  • 60

    What do you call an instrument that used to measure the specific gravity of the electrolyte in a rechargeable battery?

    hygrometer

  • 61

    An instrument which detects electric current is known as

    galvanometer

  • 62

    An open coil has

    infinite resistance and zero inductance

  • 63

    A device used in an electrical circuit to change alternating current to direct current, is known as a

    rectifier

  • 64

    It is the ratio of effective value of the counter EMF in volts to the effective value of the current in amperes

    inductive reactance

  • 65

    Which of the following circuit element stores energy in the electromagnetic field?

    inductance

  • 66

    The opposition offered to the establishment of magnetic lines of force in a magmetic circuit.

    reluctance

  • 67

    The total heating surface of any steam generating unit is comprised of?

    Those parts of boiler which are exposed on one side to only water or steam being heated, and on the other side to the combustion gases.

  • 68

    When the insulation values of a 440 volt feeder system drops below alarm level what component is opened to pinpoint to the operator location of the fault in the system?

    Feeder circuit breaker

  • 69

    The main difference between a circuit containing low voltage protection and low voltage release is that the former contains

    A momentary contact start button

  • 70

    The superposition theorem is applicable to this

    linear responses only

  • 71

    electric intensity at any point in an electric field is equal to the at that point

    potential gradient

  • 72

    The law that the induced e.m.f. Amd current always oppose the cause producing them is to

    lenz

  • 73

    The following are rating of circuit breaker except

    rater short ionization current

  • 74

    The freezing point of electrolyte in a fully charged lead-acid battery will be

    Lower than in a discharged battery

  • 75

    The amount of voltage induced in the stator windings of a modern AC generator depend mainly on

    the strenght of the magnetic field

  • 76

    The frequency of an AC generator if the load is removed?

    Governor control of the diesel engine driving the AC generator

  • 77

    Regenerative feedback implies feedback with:

    negative sign

  • 78

    A generator is prevented from being motorized by the use of a/an

    reverse power relay

  • 79

    In the flow of cycle of single AC current past any given point in a circuit, the maximum current peak occurs.

    2 times

  • 80

    Two resistors are said to be connected in series when

    same current passes in turn through both

  • 81

    What is the function of the interpoles installed in DC motors?

    To provide sparkles commutation without having to shift brushes

  • 82

    A variable shunt connected across the series field coils of a DC compound wound generator to permit a adjustment of the degree of compounding is called

    diverter

  • 83

    A hydrometer indicates specific gravity by comparing the.

    bouyancy of an object in water with the buoyancyof the same object in the liquid being measured

  • 84

    Why is it necessary to measure bolted bus bar joint resistance?

    Because as high current flows through the bus bar, any resistance in it causes resistive heating

  • 85

    Which one of the following is best described as the combinations of electrical disconnect switches and circuit breakers that are used to control, protect and isolate high-voltage electrical equipment?

    switchgear

  • 86

    A switchboard for an AC electrical system requires the use of which of the following devices?

    frequency meter

  • 87

    Heating of conductor as a result of resistance in a distribution circuit causes a power loss is demonstrate as

    line loss

  • 88

    Which of the following statement will affect he capacity value of a capacitor?

    the flow of current in the circuit

  • 89

    A lead-acid battery may become hotter than normal during a charge if the.

    battery has a shorted cell