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ET1 SEP EXAM 2018 > NAVEDTRA 14093, ELECTRONICS TECHNICIAN VOLUME 8-SUPPORT SYSTEMS > Flashcards

NAVEDTRA 14093, ELECTRONICS TECHNICIAN VOLUME 8-SUPPORT SYSTEMS Flashcards

1
Q

Which cooling method is limited in its cooling effect because it relies upon the natural airflow and requires that the equipment enclosure be of open construction without air falters?

A

Convection

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2
Q

Which type of cooling system is normally found on large equipment installations where a huge amount of heat is developed?

A

Air-to-Liquid

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3
Q

How many basic coolant systems is a typical liquid cooling system composed of?

A

2

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4
Q

How many basic liquid cooling system configurations are there in the U.S. Navy as of the time of this publication?

A

3

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5
Q

Type I (SW/DW) systems are used for electronic system installations that can be operated satisfactorily with seawater temperature as high as how many degrees?

A

95F

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6
Q

Type II (SW/DW, CW/DW) systems are used in installations that cannot accept a Distilled Water (DW) temperature higher than how many degrees?

A

90F

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7
Q

Which basic liquid cooling systems are used in installations where the temperature range is critical?

A

Type III (CW/DW)

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8
Q

The cooling water for the primary cooling system is either seawater or which other type of water?

A

Chilled

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9
Q

What are seawater systems referred to as besides one-pass?

A

Open-looped

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10
Q

Which cooling system is designed to transfer heat from the electronic equipment being cooled to the primary cooling system?

A

Secondary

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11
Q

The size of the heat exchanger on the Type I cooling system is designed to handle the full cooling load of the electronic equipment plus a margin of what percent?

A

20%

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12
Q

What will slowly dissolve the insides of various components in the primary seawater cooling system because of dissimilar metals in the cooling system?

A

Electrolysis

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13
Q

What maintains a positive pressure required on the circulating pump inlet for proper operation of the circulating pump in a liquid cooling system?

A

Expansion tank

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14
Q

What are used in the seawater cooling system to remove debris and sea life, which could clog the pressure and flow control device (orifice) and/or the tubes of the heat exchanger?

A

Strainers

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15
Q

Which type of basket strainer consists of a Y-pattern body housing a wire mesh basket?

A

Simplex

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16
Q

A duplex pressure gauge monitors the differential pressure between the inlet and outlet ports of the duplex strainer. The purpose of the duplex gauge is to provide a visual indication of a clogged strainer basket. To correctly use the gauge, it should be marked when the basket is clean. When the basket is clogged, the pressure reading is usually which psi above the clean-basket reading?

A

5 to 10

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17
Q

Which type of temperature regulating valve is used where seawater is the primary cooling medium in the heat exchanger?

A

Three-way

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18
Q

Which type of temperature regulating valve is used where chilled water is the primary cooling medium in the heat exchanger?

A

Two-way

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19
Q

The three-way temperature regulating valve’s range of operation is within how many degrees of the setting on the valve?

A

+ or - 5 degrees

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20
Q

What are used to reduce the pressure or the flow of coolant through a cooling system?

A

Flow regulators

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21
Q

To stabilize the flow of seawater and to prevent jet erosion of the heat exchanger and associated piping, the orifice plate should be installed with at least how many pipe diameters of straight pipe upstream from the heat exchanger?

A

15

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22
Q

Where is the constant flow regulator installed in relation to the heat exchanger when used with the chilled-water system?

A

Downstream

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23
Q

Most systems incorporate one or more types of devices to monitor the flow of distilled water through the system to ensure that the electronic equipment is supplied with an adequate flow. which type of switch is normally found in the secondary cooling system to monitor the overall coolant flow?

A

Low-flow

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24
Q

How many types of system flowmeters are installed aboard ships?

A

3

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25
Q

As the coolant approaches the contracted portion (throat) of the meter, its velocity must increase as it flows through the contracted zone in which type of flowmeter?

A

Venturi

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26
Q

Which type of flowmeter uses a flat plate with a hole in it which causes a considerable loss of pressure downstream?

A

Orifice

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27
Q

The efficiency of the orifice flowmeter can be as low as what percent?

A

65%

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28
Q

Which type of flowmeter is a variable area orifice meter that functions by maintaining a constant differential pressure with varying flow?

A

Rotameter

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29
Q

How many secondary distilled water circulating pumps does each cooling system have?

A

2

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30
Q

How many major elements does the centrifugal pump have?

A

2

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31
Q

What is used to maintain secondary cooling system water in an ultrapure state?

A

Demineralizer

32
Q

The demineralizer is sized so that what percentage of the cooling system volume passes through the demineralizer every hour?

A

5%

33
Q

The submicron filter is used to remove small particles from coolant flow having a size greater than how many microns?

A

.5

34
Q

How many conductivity cells monitor the coolant through the demineralizer?

A

2

35
Q

What is the reciprocal of resistance?

A

Conductance

36
Q

Typical operating requirements for the demineralizer are conductivity 1 micromno/cm at 77F (resistivity 1 megohm/cm at 77F), oxygen content 0.1 ppm by weight, and mechanical filtration of how many microns absolute?

A

0.5

37
Q

When a demineralizer system is filled with a fresh charge of water, it should be allowed to circulate for approximately how many hours before comparing the input and output readings?

A

2

38
Q

What is primarily used in some waveguide systems to increase the dielectric constant inside the waveguide to prevent RF energy from arcing inside it?

A

Dry air

39
Q

What is the approximate dry air pressure in high-power waveguide runs?

A

20-35 psig

40
Q

What is the approximate dry air pressure in low-power waveguide applications?

A

1-8 psig

41
Q

A high-power waveguide system requires dry air at a pressure of 25 to 35 psig with a dew point of how many degrees at atmospheric pressure?

A

-40F

42
Q

What is the temperature at which water vapors begin to deposit as a liquid?

A

Dew point

43
Q

Which type of equipment air dryers are installed in electronic equipment?

A

Desiccant

44
Q

The purpose of the desiccant air dryer is to remove oil and water in both forms, automatically and continuously, and to deliver clean, very dry air for pressurization of equipment waveguides. Which mode is the air dryer normally in?

A

Bypass

45
Q

What is designed to limit the output of the desiccant air dryer should the output of air increase beyond the limits of the dryer capability?

A

Flow limiter

46
Q

Which system is the link between the ship’s source of electrical power and the ship’s electrical loads?

A

Electrical distribution

47
Q

Most AC power distribution systems in naval ships are how many-volt, three-phase, 60-Hertz, three-wire systems?

A

450

48
Q

What interconnect the ship’s service generator and distribution switchboards so any switchboard can be connected to feed power from the generators to one or more of the other switchboards allowing the generators to operate in parallel?

A

Bus ties

49
Q

What is the phase sequence in Naval ships?

A

ABC

50
Q

Which type of equipment is used to provide two sources of power to equipment that is vital to the ship?

A

Bus transfer

51
Q

Which type of switches may be used to switch from normal to alternate or emergency power for those loads that draw a large starting current or for which some condition must be met before energizing?

A

Manual Bus Transfer (MBT)

52
Q

Which type of switches are used to provide two sources of power to those loads that MUST be re-energized as soon as possible after a sudden loss of normal power?

A

Automatic Bus Transfer (ABT)

53
Q

How many distinct groups or shipsets of distribution switchboards are there aboard modern Navy vessels at the time of this publication?

A

3

54
Q

How many distinct functions are provided by switchboards aboard ships?

A

3

55
Q

A set of how many ground detector lamps is connected through transformers to the main bus of each ship’s service switchgear group?

A

3

56
Q

Which type of generators produce most of the electric power used today?

A

Alternating Current (AC)

57
Q

How many distinct sets of conductors do all generators have at a minimum?

A

2

58
Q

Which two major assemblies are AC generators built in since relative motion is needed between the armature and field flux?

A

Stator and Rotor

59
Q

A three-phase ac generator, as the name implies, has three single-phase windings spaced so that the voltage induced in each winding is how many degrees out of phase with the voltages in the other two windings?

A

120 degrees

60
Q

Rather than have six leads come out of the three-phase ac generator, one of the leads from each phase may be connected to form a common junction. What is the stator then said to be besides star, or connected?

A

Wye

61
Q

Which type of connected AC generator is the start end of one phase winding is connected to the finish end of the third; the start of the third phase winding is connected to the finish of the second phase winding; and the start of the second phase winding is connected to the finish of the first phase winding?

A

Delta

62
Q

Which type of device has no moving parts and transfers energy from one circuit to another by electromagnetic induction?

A

Transformer

63
Q

Which type of transformer receives electrical energy at one voltage and delivers it at a higher voltage?

A

Step-up

64
Q

Which type of transformers have a low volt-ampere capacity and are less efficient than large constant-potential power transformers?

A

Power-supply

65
Q

Most power-supply transformers for electronic equipment are designed to operate at a frequency of how many Hz?

A

50-60

66
Q

Which frequency are most aircraft power-supply transformers designed for?

A

400 Hz

67
Q

How many windings does the typical transformer have which are electrically insulated from each other?

A

2

68
Q

What is the most common type of distribution transformers?

A

Core

69
Q

Which system provides the means for making temporary connections to vital circuits and equipment?

A

Casualty power

70
Q

Casualty power runs involve more than one repair party on large ships. All repair parties should rig simultaneously. Which rule should always be observed while rigging?

A

Rig from load to serve

71
Q

Which portable cable is used in AC casualty power systems?

A

Navy LSTHOF 42

72
Q

What is the normal carrying capacity of the Navy LSTHOF 42 cable?

A

93 amperes

73
Q

What is the Navy LSTHOF 42 cable casualty rating?

A

200 amperes

74
Q

How many hours without damage to the cable can the Navy LSTHOF 42 carry 200 amperes under normal conditions?

A

4

75
Q

How many amperes are shore-power cables rated at?

A

400

76
Q

What is used when connecting shore-power to the ship to ensure proper phase relationship between ship power and shore power?

A

Phase-sequence indicator

ET1 SEP EXAM 2018 (28 decks)

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