問題一覧
1
Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel-cage motor does not?
Slip rings
2
Periodic testing of circuit breakers is necessary to assure that a correct rated and properly installed unit ____.
will continue to provide the original degree of protection
3
A current at which a magnetic-type overload relay tends to trip maybe decreased by raising the plunger further into the magnetic circuit of the relay. This action will ____.
Increases magnetic pull on the plunger and requires less current to trip the relay
4
What electrical apparatus can test insulating efficiency in an electric installation?
Megger tester
5
What is the cause when an alternator failed to produce line voltage?
exciter generator failure
6
Which of the listed precautions should be observed before spraying liquid solvent on the insulation of an electric motor?
Disconnect the motor from the power source.
7
Moisture as a result of condensation occurring inside of the cargo winch master switches, can be reduced by?
using strip heaters inside the switch box
8
An electric tachometer receives the engine speed signal from?
bimetallic sensing device
9
A fuse the blows often should be replaced only with a fuse of ______.
the recommended current and voltage rating
10
Upon failure of the normal power supply, the emergency generator is placed on the line by the _____.
automatic bus transfer devise
11
It is a type of temperature sensor that has the characteristic of being very accurate, linear and has a good long term stability.
RTD'S
12
Before working on an electric motor starter panel located on the main deck, what should you do FIRST?
Open the circuit breaker and tag out
13
If both the "high level" and "low level"" alarms come on for the same address of a centralized control console, the most likely problem is a/an
sensor failure
14
Which of the following statements best describes the material known as varnished cambric?
Cotton cloth coated with insulating varnish.
15
What may happen to the components of a winch master control switch, if the cover gasket becomes deteriorated?
Rapid corrosion of switch components.
16
A three-phase squirrel-cage induction motor will run hot due to ____.
Open stator coils
17
What is the first step to properly use a hook-on-type volt/ammeter in checking current flow?
hook the jaws of the instrument around the insulated conduct
18
Electrical leads and insulation on a motor should be painted with _____?
insulating varnish
19
What is the result if the solenoid coil burns on a cargo winch with an electrical brake?
The brake will be set by spring force.
20
What kind of instrument used to measure the specific gravity, or "charge" of the electrolyte of a storage battery?
Hydrometer
21
A reversible electric motor with worm gear that is connected to the flywheel to position engine parts is the _____ .
turning gear
22
The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the
main switchboard
23
Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by ____.
feeding current into the windings at low voltage
24
What indicates the third color band on a resistor?
number of zeros following the first two significant figures in the resistance value
25
A temperature instrumentation system for an accomodation reefer room consists of a resistance temperature detector(RTD), a measuring bridge circuit, and a meter or alarm circuit. Which of the following statements is true concerning the measuring bridge circuit?
The resistance bridge is said to be balanced when its output voltage is zero
26
Which device that commonly utilizes the principle of electromagnetic induction?
transformer
27
Electrical Insulating rubber gloves should be dielectrically tested every how many months?
6 months
28
Which of the following materials is recommended for finishing the slip rings after grinding or turning?
crocus cloth
29
What do do you call on a periodic testing by a shore side support technician using a special camera which can detect potentially dangerous loose or corroded bus bar and controller connections?
heat sensitive thermography
30
What devices is fitted to prevent the generator windings from absorbing moisture while at standstill?
Space heater
31
A molded-case breaker provides protection against short circuits by using?
electromagnet
32
When charging lead-acid batteries, you should reduce the charging rate as the battery nears its full charge capacity to _____.
prevent excessive gassing and overheating
33
A capacitor can be tested using a megohmmeter or an ohmmeter, if the meter is connected to a shorted capacitor, the meter pointer should ______.
immediately deflect to and remain at zero
34
Two contributors of electronic console failures are heat and vibration. To combine some of their effect, preventive maintenance procedures should include ____.
periodic changing or cleaning of console ventilation and control room air conditioning filters
35
In the event of a power failure during cargo loading operations, which of the following can stop the movement of an electric powered cargo winch?
A spring set brake
36
A common type of protective covering used on electrical conductors is
rubber or plastic
37
You are testing the insulation in an AC generator with with a megohmeter. the resistance value of a dry, clean winding will ______.
continue to rise as the test potential is maintained, becoming fairly steady as the leakage current stabilizes
38
The charging of lead-acid storage batteries will always result in ?
a dangerously explosive gas being liberated
39
Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness?
Place heat lamps in the motor housings
40
Which of the following statements is true concerning the cleaning of electrical contacts?
Delicate parts should be cleaned with a brush and an approved safety solvent
41
The division of kilowatt load between two paralleled alternators is determined by the ?.
load-speed characteristics of the governors
42
Which of the following statements concerning analog and digital devices are correct?
The variables in digital systems are fixed quantities and the variables in analog systems are continuous quantities.
43
A self-excited DC generator fails to come up to its normal 440 volts. What could be the probable cause?
low armature speed
44
A common type of protective covering used on electric conductors is _____
fibrous braid
45
Regulations require each motor controller to have a wiring diagram located ______.
on the inside of the controller door
46
How should controller contacts be routinely cleaned?
wiping with a clean dry cloth
47
If a small electric motor is immersed in salt water it should be _____. I. washed in fresh water II. dried in an oven III. blow air until it dries
I only
48
When reading electrical motor controller diagrams, it helps to know that ______.
current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines
49
What is a device that converts fluid powers into linear mechanical force and motion that consists of a movable piston, connecting rod, and plunger operating in a cylindrical cavity?
Cylinder
50
How much is the typical resistance of the body from hand to foot when dry?
500 ohms
51
When a nickel-cadmium battery begins gassing while connected to the battery charging circuit, you should _____.
do nothing as this is a normal condition when charging.
52
What would indicate ground in a particular phase 3 - phase low voltage distribution system?
dark or dim switchboard ground detecting light
53
How can you restore the charge of a lead-acid battery?
passing a direct electric current through the cell
54
The purpose of a motor under voltage protection device is to _____.
prevent high armature current when power is restored
55
Four lamps are connected in parallel in a single circuit. If one of the lamp burns out, the others will?
burn with their original intensities
56
A switchboard for an AC electrical system requires the use of which of the following devices?
Frequency meter
57
What should you use to determine if a stator coil is grounded?
megger
58
In an impressed current cathodic protection system, what is anode
insulated from the hull and does not waste away.
59
The purpose of a main switchboard circuit breaker's reverse-power trip is to _____.
prevent alternator motorization
60
The electrolyte in a lead-acid storage battery consists of distilled water and ?
sulfuric acid
61
When shipboard electrical distribution circuits are connected in parallel, additional parallel circuits will cause the total circuit resistance to ___ .
decrease, causing an increase in the line current
62
If a small electric motor is immersed in salt water it should be _____. I. washed in fresh water II. dried in an oven III. blow air until it dries
I only
63
When a lead-acid battery begins gassing freely while receiving a normal charge, what should you do when charging?
be decreased
64
Air gap readings should be periodically taken for electrical generation equipment. The best tool to use to take these measurement is a ____.
tapered, long blade gage
65
When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by the megohmmeter's pointer?
kicking slightly down scale as voltage is applied
66
Why should you use a high impedance multimeter when troubleshooting electronic equipment?
so as not to load down the circuit and obtain erroneous voltage readings
67
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?
The unit should remain off for the specified amount of time so as not to disturb curing
68
Before reassembling any machinery, what should you do?
clean any corroded surfaces and file all burrs smooth
69
What should be done to protect the rotor of a motor disassembled for maintenance of overhaul?
it must be supported by two "V" notched wood blocks
70
It is a type of electrical fault that happens when a phase conductor is completely or partially interrupted:
Open circuit fault
71
What is used in most for starting three-phase induction motors of five (5) horsepower less?
across-the-line starters
72
The automatic voltage regulators provide on switch boards has function to _____.
vary the field excitation to the generators
73
What gives the information about the speed of a motor in D. C. Generator,?
Speedometer
74
The proper way to apply plastic electrical tape to an electric cable splice is to _____.
wind the tape so that each turn overlaps the turn before it.
75
The insulation resistance of electric equipment and machinery should be tested for lowest normal insulation valves _____.
immediately after shutting down of the machine
76
Encrusted dirt accumulated inside a motor should be removed with a ______
Fiber scraper
77
When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered _____.
in parallel
78
When a replacing a fuse with one of a higher rating than the original, which of the following is true?
endangers the apparatus it is supposed to protect
79
If a delicate component must be soldered into a circuit the component may be protected from the heat of the soldering process by _____.
using a thermal shunt
80
When trouble shooting electronic equipment, what is the first step to be taken before testing the circuit voltage?
check the voltage supply from the power source
81
Which of the following statements concerning the maintenance of solid silver Contacts in relay and auxiliary control circuits is correct?
They should be filed with a fine-cut file when projections extend beyond the contact surface.
82
The greatest single cause of electrical failure is ____.
The breakdown of insulation
83
A temperature instrumentationsystem for an engine room console consistes of a resistance temperature detector(RTD), a measuring bridge circuit, and a meter(or alarm circuit). Which of the following statements is true concerning the measuring bridge circuit?
The resistance bridge is said to be balanced when its output voltage is zero
84
Any electric motor can be constructed to be?
Explosion proof
85
Which of the following statements represents the FIRST step in seating new brushes on slip rings?
Lay sandpaper between the brush and the slip ring and slide the sandpaper back and forth under the brush.
86
To check the three line fuses of three-phase system consisting of a three-phase motor, must _______.
make sure the motor is operating at full load to guard against a false reading
87
What does the variable resistance placed in the rotor circuit of a wound-rotor induction motor provide?
speed control
88
Electrically operated safety devices on auxiliary diesel engines functions to stop the engine by ____.
shutting off fuel supply
89
In the circle diagram for induction motor, the diameter of the circle represents _____.
rotor current
90
Which of the following data is required to draw the circle diagram for an induction motor?
Bolck rotor test, no load test and stator resistance test
91
What kind of electrical cable that is widely used and is highly resistant to mechanical damage?
Aluminum cable covered with insulation.
92
The schematic symbol for an operational amplifier in an analogue circuit is a _____.
Triangle
93
The removal of paint from electrical equipment such as generators, should be cautiously undertaken because _____.
the paint dust is composed of abrasive and semi-conducting materials which impakt insulation
94
What is a variable resistance component used as a control device in electrical circuit?
Potentiometer
95
Which test on a transformer provides information about the regulation, efficiency and heating under load condition?
Back to back test
96
What will you do if the generator is exposed to rain or any water?
Make a megger test
97
What is a three-layer bidirectional device used primarily as a trggering device with junctions heavily and equally doped?
Diac
98
A temperature instrumentation system for an engine room console consistes of a resistance temperature detector(RTD), a measuring bridge circuit, and a meter(or alarm circuit). Which of the following statements is true concerning the measuring bridge circuit?
The resistance bridge is said to be balanced when its output voltage is zero
99
periodic testing of circuit breakersis necessary to assure that a correct rated and properly installed unit ____.
will continue to provide the original degree of protection
100
To carry out an insulation resistance test, one terminal of the megohmmeter should be connected to the winding, with the other terminal being connected to the _____.
frame of the machine