[Generators and Switchboards] Flashcards
How many volts are brushless generators?
240-450 V
How does the operator monitor the power from the generators?
Main power distribution switchboard
What is loss of power in the form of heat called?
Hysteresis loss
What provide power to bus bars inside the switchboards and each distribution panel?
Feeders (large cables)
What is a smaller version of the main distribution switchboard that provides power to vital services?
Emergency switchboard
What is converted into energy to turn the generator?
Fuel
What is a chemical process that reduces the number of electrons in a substance because the electrons migrate to other areas?
Oxidation (rust)
What is the electrical/physical connection between the main and emergency switchboard bus bars?
Bus tie
What is accomplished by connecting a battery to the exciter field terminals?
Flashing the field
What controls the ship service generated power and shore power?
Main power distribution switchboard
How are brushless generators rated?
Kilovolt-ampere (kVA) at a specified power factor (PF)
What consolidates all the motor controlling equipment for all the major motors onboard the vessel?
Motor Control Center (MCC)
What controls the output of the generator by controlling the magnetic field in the stationary exciter field winding?
Voltage regulator
What refers to physical connections between conductive materials and the earth?
Grounding
What is used to show the change in current direction of the AC system?
Sine wave
What leave the distribution panel circuit breakers and provide power to individual loads?
Branch circuits
What type of grounding system do Army watercraft use?
Ungrounded current-carrying
Where are the four sets of generator windings in the brushless generator?
- 2 are connected to generator mainframe
* 2 are fitted to the rotor shaft
What support the mainframe?
Mounts
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?
Amortisseur (damper windings)
What is a ground system that uses an insulated current-carrying conductor and a direct wiring connection to the earth?
Neutral system
What states: “An induced effect is always such, as to oppose the cause that produced it?”
Lenz’s Law
What are used to carry the large generator loads within the switchboard?
Bus bars
What consists of four to eight individual coils or pole pieces keyed to the rotor shaft?
Main rotating field
What is the chemical process in which a substance loses or gains electrons?
Electrolysis
Which end contains a bearing that supports the internal rotor shaft?
Bell end
What is a three-conductor, three-phase rotating winding located directly inside the exciter stator?
Exciter armature
What allows an abnormal circuit to be separated from the electrical distribution system very close to the fault?
Selective tripping
What is used to change the exciter portion output from AC to DC?
Rotating rectifier
What is a strong metallic structure surrounding and retaining the stationary windings?
Mainframe (housing)
What is the stationary DC energized winding where the DC magnetic field is initially developed?
Exciter field
What device allows alternating voltages to be stepped up or down in amplitude?
Transformer
How should dirt and grease/oil be removed?
Dirt should be vacuumed and grease/oil should be cleaned with lint-free rags
What are rubber composition or springs incorporated into the mounts as shock absorbers?
Resilient mounts
What indicates one cycle per second?
Hertz
When contamination is found, what should be used to check the insulation values?
Megger
Who supervises internal inspection of the ship service generator?
Chief engineer or their appointed representative
What is 180 degrees of rotation called?
Alternation
What is designed to change electrical energy back into mechanical energy to do work?
Electric motor
What is the prime mover for the generator?
Diesel engine
What portion of the generator is connected to the diesel engine?
Yoke end (frame end)
1) Where are the main generators located?
2) Where is the emergency generator located?
1) Engine room
2) Above the waterline in a separate compartment
How is the speed of the generator calculated?
Frequency
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# of pairs of poles
What are the two basic power sources for the switchboard?
- Generator
* Shore power
How many separate windings do PMGs (Permanent Magnet Generators) have?
6
How many windings are in the brushless generator?
4
What of an AC generator must not change?
Frequency
What determines the speed the prime mover must turn the rotor to maintain a frequency of 60 Hz?
Number of poles
What are installed in switchboards and distribution panels to separate abnormally operating electrical apparatus from the rest of the system?
Circuit breakers and fuses
What is the grounded conductor in the case of Army watercraft?
Hull of the vessel
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?
Grounding strap (flexible shunt)
What is the current produced by Earth?
Telluric current
In the neutral ground system, what is insulated throughout its circuit and retains the circuit breaker protection?
Phase conductor
In the neutral ground system, what is insulated throughout the entire circuit, normally without a circuit breaker?
Neutral conductor
In the neutral ground system, what is the safety circuit designed specifically to carry current during an abnormal condition to protect the operator?
Ground wire
What have an outstanding resistance to oxidation?
Noble metals (zinc anodes)
What means that the generator is supplying power through the switchboard to the loads?
On line
What automatically connects the emergency generator to the emergency switchboard when power is lost?
Automatic Bus Transfer (ABT) switch
What is the most critical setting for paralleling AC generators?
Voltage setting
What is happening when the generator is connected to the bus, but is not delivering power?
Floating on the line
In electronic governors, what provide the voltage and current necessary for operating the electronic fuel control system?
Batteries
What connect to the bus monitor and protect the feeders and branch circuits?
Automatic over current protective devices
