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