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88L10 > [Generators and Switchboards] > Flashcards

[Generators and Switchboards] Flashcards

1
Q

How many volts are brushless generators?

A

240-450 V

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3
Q

How does the operator monitor the power from the generators?

A

Main power distribution switchboard

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4
Q

What is loss of power in the form of heat called?

A

Hysteresis loss

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6
Q

What provide power to bus bars inside the switchboards and each distribution panel?

A

Feeders (large cables)

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7
Q

What is a smaller version of the main distribution switchboard that provides power to vital services?

A

Emergency switchboard

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8
Q

What is converted into energy to turn the generator?

A

Fuel

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9
Q

What is a chemical process that reduces the number of electrons in a substance because the electrons migrate to other areas?

A

Oxidation (rust)

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12
Q

What is the electrical/physical connection between the main and emergency switchboard bus bars?

A

Bus tie

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14
Q

What is accomplished by connecting a battery to the exciter field terminals?

A

Flashing the field

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15
Q

What controls the ship service generated power and shore power?

A

Main power distribution switchboard

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18
Q

How are brushless generators rated?

A

Kilovolt-ampere (kVA) at a specified power factor (PF)

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20
Q

What consolidates all the motor controlling equipment for all the major motors onboard the vessel?

A

Motor Control Center (MCC)

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21
Q

What controls the output of the generator by controlling the magnetic field in the stationary exciter field winding?

A

Voltage regulator

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22
Q

What refers to physical connections between conductive materials and the earth?

A

Grounding

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23
Q

What is used to show the change in current direction of the AC system?

A

Sine wave

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24
Q

What leave the distribution panel circuit breakers and provide power to individual loads?

A

Branch circuits

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27
Q

What type of grounding system do Army watercraft use?

A

Ungrounded current-carrying

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28
Q

Where are the four sets of generator windings in the brushless generator?

A
  • 2 are connected to generator mainframe

* 2 are fitted to the rotor shaft

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30
Q

What support the mainframe?

A

Mounts

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32
Q

What are short-circuited at each end to allow currents to circulate so that a magnetic field can be produced to oppose any change in prime mover motion?

A

Amortisseur (damper windings)

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33
Q

What is a ground system that uses an insulated current-carrying conductor and a direct wiring connection to the earth?

A

Neutral system

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34
Q

What states: “An induced effect is always such, as to oppose the cause that produced it?”

A

Lenz’s Law

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35
Q

What are used to carry the large generator loads within the switchboard?

A

Bus bars

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38
Q

What consists of four to eight individual coils or pole pieces keyed to the rotor shaft?

A

Main rotating field

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39
Q

What is the chemical process in which a substance loses or gains electrons?

A

Electrolysis

45
Q

Which end contains a bearing that supports the internal rotor shaft?

A

Bell end

46
Q

What is a three-conductor, three-phase rotating winding located directly inside the exciter stator?

A

Exciter armature

48
Q

What allows an abnormal circuit to be separated from the electrical distribution system very close to the fault?

A

Selective tripping

49
Q

What is used to change the exciter portion output from AC to DC?

A

Rotating rectifier

51
Q

What is a strong metallic structure surrounding and retaining the stationary windings?

A

Mainframe (housing)

52
Q

What is the stationary DC energized winding where the DC magnetic field is initially developed?

A

Exciter field

53
Q

What device allows alternating voltages to be stepped up or down in amplitude?

A

Transformer

57
Q

How should dirt and grease/oil be removed?

A

Dirt should be vacuumed and grease/oil should be cleaned with lint-free rags

58
Q

What are rubber composition or springs incorporated into the mounts as shock absorbers?

A

Resilient mounts

61
Q

What indicates one cycle per second?

A

Hertz

62
Q

When contamination is found, what should be used to check the insulation values?

A

Megger

63
Q

Who supervises internal inspection of the ship service generator?

A

Chief engineer or their appointed representative

68
Q

What is 180 degrees of rotation called?

A

Alternation

69
Q

What is designed to change electrical energy back into mechanical energy to do work?

A

Electric motor

70
Q

What is the prime mover for the generator?

A

Diesel engine

71
Q

What portion of the generator is connected to the diesel engine?

A

Yoke end (frame end)

72
Q

1) Where are the main generators located?

2) Where is the emergency generator located?

A

1) Engine room

2) Above the waterline in a separate compartment

73
Q

How is the speed of the generator calculated?

A

Frequency
—————————
# of pairs of poles

74
Q

What are the two basic power sources for the switchboard?

A
  • Generator

* Shore power

75
Q

How many separate windings do PMGs (Permanent Magnet Generators) have?

A

6

76
Q

How many windings are in the brushless generator?

A

4

77
Q

What of an AC generator must not change?

A

Frequency

78
Q

What determines the speed the prime mover must turn the rotor to maintain a frequency of 60 Hz?

A

Number of poles

79
Q

What are installed in switchboards and distribution panels to separate abnormally operating electrical apparatus from the rest of the system?

A

Circuit breakers and fuses

80
Q

What is the grounded conductor in the case of Army watercraft?

A

Hull of the vessel

81
Q

What is attached from the generator housing to the engine bed to connect the diesel generator set to the engine bed with a conductive path?

A

Grounding strap (flexible shunt)

82
Q

What is the current produced by Earth?

A

Telluric current

83
Q

In the neutral ground system, what is insulated throughout its circuit and retains the circuit breaker protection?

A

Phase conductor

84
Q

In the neutral ground system, what is insulated throughout the entire circuit, normally without a circuit breaker?

A

Neutral conductor

85
Q

In the neutral ground system, what is the safety circuit designed specifically to carry current during an abnormal condition to protect the operator?

A

Ground wire

86
Q

What have an outstanding resistance to oxidation?

A

Noble metals (zinc anodes)

87
Q

What means that the generator is supplying power through the switchboard to the loads?

A

On line

88
Q

What automatically connects the emergency generator to the emergency switchboard when power is lost?

A

Automatic Bus Transfer (ABT) switch

89
Q

What is the most critical setting for paralleling AC generators?

A

Voltage setting

90
Q

What is happening when the generator is connected to the bus, but is not delivering power?

A

Floating on the line

91
Q

In electronic governors, what provide the voltage and current necessary for operating the electronic fuel control system?

A

Batteries

92
Q

What connect to the bus monitor and protect the feeders and branch circuits?

A

Automatic over current protective devices

88L10 (22 decks)

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