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76 Cards in this Set
- Front
- Back
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What is the unit of measurement that refers to the electrical capacity of a
battery? |
Ampere-Hours
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what is is used to recharge the battery between scheduled complete
maintenance cycles?. |
Boost charge
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What is the discharge measured quantitatively in ampere-hours at a specified discharge rate (i.e., the length of time during which the battery is discharged) to a specified cutoff voltage?,
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Capacity
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What is is the voltage point on the discharge curve, for a specified
discharge rate, at which the battery or cell is considered to be discharged for all practical purposes? |
cutoff voltage
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What are the two charge methods presently used to charge nickel-cadmium batteries in a battery servicing facility?
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constant-potential method and constant-current method
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What is is the fastest method of charging a nickel-cadmium battery?
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constant-potential method
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What is the preferred method of maintenance charging nickel-cadmium batteries?
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constant-current method
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What are the primary factors that influence battery capacity?
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Sustained high battery current and extreme temperatures
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What in nickel-cadmium battery must be monitored periodically and adjusted
to compensate for water loss. |
electrolyte level
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What is the maintenance
interval for a Low-Maintenance Vented Battery? |
one year
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when current for a fully charged nickel-cadmium battery rises out of proportion to the impressed voltage is known at what?
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Thermal runaway
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Battery: What is the Charging method which applies a fixed voltage to a cell?
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CONSTANT POTENTIAL
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Battery: what is the Charging method in which current does not change appreciably in magnitude,regardless of battery voltage or temperature.
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CONSTANT CURRENT.
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The available ampere-hours in a battery at any given time is known as?
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STATE-OF-CHARGE
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lead- acid batteries do not have to be returned to the battery shop unless what?
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It fails to perform or reaches the end of its service life.
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What are the advantages of using transformers
and transformer rectifiers vice inverters and dynamotors for supplying aircraft power? |
Lightweight, more reliable, and simple to maintain
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What power system requirements do modern
naval aircraft have? |
120-/208-volt ac, 3 phase and 400 Hz
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What determines the voltage frequency of an ac generator?
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The number of magnetic poles and the rotor rpm
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What are the two types of ac generators?
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Brush and brushless
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What supplies the output ac power of a generator?
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The stator
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How many phases is an ac generator?
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Three
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What are the advantages of a brushless generator
over a brush-type generator? |
Increased reliability and greater operating time between overhaul
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What is a prime mover?
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A device that provides the driving force for a generator
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What is the purpose of a CSD?
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Convert variable engine speed to a constant speed output
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What are inverters?
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An emergency source of ac power when normal ac power fails
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In an inverter, what converts electrical energy
to mechanical energy? |
The dc motor
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On what does the rating of an aircraft inverter
depend? |
The equipment that it will supply
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What is the purpose of a transformer?
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To convert an input ac voltage into a usable ac output voltage by either stepping
up or stepping down that voltage |
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What is the function of a transformer
rectifier? |
To convert ac input voltage to a dc output voltage
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What is the only moving part in a transformer
rectifier? |
The cooling fan
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What is the difference between an autotransformer
and an ordinary transformer? |
An autotransformer has one winding that is common to both primary and
secondary windings |
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Autotransformers offer savings in both size and costs over conventional units. When are
these savings greatest? |
When the turns ratio is less than 2:1
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What are the two general types of instrument
transformers? |
Current and potential
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What components maintain the aircraft (a/c)
storage battery in a charged state? |
Ac generator and transformer rectifier
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What are the two most common types of a/c
storage batteries in use today and what are the colors of each? |
Lead-acid which have a red case and nickel-cadmium which have a blue case
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What manual is used for information of securing, storing, servicing, and handling a/c storage batteries?
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NAVAIR 17-15BAD-1
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On a VLAB, what is the purpose of the vent nozzles?
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The upper nozzle is connected to a tube that supplies definite pressure on the
battery while in flight. The lower nozzle is connected to a negative pressure tube, allowing battery acid to drain without damaging the aircraft |
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The sump jar of a VLAB system contains a felt
pad moistened with what? |
Sodium bicarbonate
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In a VLAB system, what is the purpose of the sump jar and the felt pad?
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To neutralize the gases and excess battery solution
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What type of electrolyte is used in a SLAB?
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A mixture of sulfuric acid and water
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In a SLAB, how is electrolyte immobilization accomplished?
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By using a gel or special mats to absorb electrolyte
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What is considered the fundamental unit of a
NICAD battery? |
The cell
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What are the types of cells used in NICAD batteries?
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Vented and sealed
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What is the nominal value of a NICAD battery cell?
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1.26 volts dc
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Why can the hydraulic driven emergency generator only power a small number of circuits?
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The kVA rating is too low
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What causes the rotor in the generator to turn?
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The hydraulic motor
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What helps to maintain generator output frequency?
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The motor converts 3000 pounds per square inch of fluid to a constant speed
rotation |
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How is the generator cooled?
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hydraulic fluid
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This provides voltage regulation and fault detection of the generator output.
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motor-generator control
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What is It ithat s de-energized when primary electrical power is lost and allows hydraulic
fluid to be routed to the hydraulic motor to drive the generator? |
solenoid control valve
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What are the two main sections of an APU?
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Accessory assembly and compressor/turbine assembly
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The electrical system of an APU consists of
what components? |
Holding relays, oil pressure switch, centrifugal switch assembly, hour meter, and
wiring harness |
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APU ignition cuts out at what rpm?
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95%
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What is the purpose of the centrifugal speed
switch assembly? |
It controls the sequence of operation of various electrical components
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How many sub-switches make up the
centrifugal speed switch assembly? |
Three
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How are the centrifugal speed switches adjusted?
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By using an adjustment screw to apply spring tension to the lever arm
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What are the functions of the apu's 35%, 95%, 106% switches?
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35%—shuts the starter down; 95%—arms load control circuit, starts hour meter,
and shuts off ignition; 106%—overspeed protection (shuts down the APU during an overspeed condition |
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Changing the setting of the 35% switch also
affects what? |
The settings of the 95% and 106% switches
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How does the 106% switch shut down the
APU? |
When the switch is actuated it cuts off fuel flow, causing the APU to shut down
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At what rpm is the starter disengaged?
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35%
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What could happen to the APU starter if the
dropout relay fails? |
The starter may fail internally due to an overheat or overspeed condition
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What is the most common method of voltage
regulation for ac generators? |
Varying the current to the field windings
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Why would we use a permanent magnet on the
generator rotor in place of exciter windings? |
It helps to maintain a constant load on the generator and simplifies generator
construction |
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What happens when magnetic fields of alternating polarity pass across the armature
windings? |
Ac voltage induction occurs
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What controls the voltage induced into the
armature windings? |
1. The number of turns of conductor per winding
2. Generator rpm 3. Magnetic field strength |
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What must ac generator control systems
protect against? |
1. Over- or undervoltage
2. Over- or underfrequency 3. Improper phase sequence |
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What is the purpose of the rotating
three-phase rectifier in a brushless generator? |
Change the rotating ac output voltages of the exciter to dc voltages
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What is the chief advantage of having dc
exciter units integrated into ac generators? |
Each generator has its own independent source of excitation so no external
source of electrical power is necessary |
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What is the only moving mechanical part in a
solid state voltage regulator? |
Exciter control relay
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What component provides circuit protection
for an ac generator? |
Supervisory panel
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A supervisory panel will disconnect the generator
from the load under what conditions? |
Over-/underfrequency
Over-/undervoltage Feeder fault |
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What is the required output frequency of the
PMG? |
600 Hz
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How many amperes are required through the
exciter coil to generate a 120-/208-volt, 60-kilovolt ampere (kVA) load? |
1.7 amps
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During an undervoltage condition, at what
voltage will the generator be dropped off line? |
When one or more phases drops to 90 volts or less
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At what voltage will the generator be dropped
off line during an overvoltage condition? |
When one or more phases is 129 volts or greater
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A condition where the current leaving the generator does not pass through the
load |
feeder fault
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