11.6 Electrical Power Flashcards by John Watts

What are the main components of the electrical power system?
A. Generation and storage subsystems.
B. Generation and distribution subsystems.
C. Distribution and backup subsystems.

B. Generation and distribution subsystems.

How well did you know this?

Not at all

Perfectly

What is the function of the generation subsystem in the electrical power system?
A. To produce electrical energy at the required parameters.
B. To distribute electrical energy to all consumers.
C. To store electrical energy for later use.

A. To produce electrical energy at the required parameters.

How well did you know this?

Not at all

Perfectly

What is the role of the distribution subsystem in the electrical power system?
A. To store electrical energy for emergency use.
B. To provide electrical energy to all the consumers.
C. To generate electrical energy at the necessary parameters.

B. To provide electrical energy to all the consumers.

How well did you know this?

Not at all

Perfectly

What are the primary uses of the aircraft battery?
A. To supply power to the aircraft lighting system.
B. To provide emergency power and APU starter motor power.
C. To operate cabin ventilation fans.

B. To provide emergency power and APU starter motor power.

How well did you know this?

Not at all

Perfectly

What is the primary type and function of the main aircraft battery?
A. A lead-acid battery that supplies power to cabin lights.
B. A nickel-cadmium battery providing 24 Vdc to DC power distribution when no other source is available.
C. A lithium-ion battery designed to start the engines.

B. A nickel-cadmium battery providing 24 Vdc to DC power distribution when no other source is available.

How well did you know this?

Not at all

Perfectly

What is the minimum requirement for the aircraft battery in emergency situations?
A. To supply power to non-essential systems for 15 minutes.
B. To ensure power to all essential consumers for at least 30 minutes.
C. To recharge itself while providing power to all systems.

B. To ensure power to all essential consumers for at least 30 minutes.

How well did you know this?

Not at all

Perfectly

What are the two types of main batteries commonly fitted to aircraft?
A. Lithium-ion and Lead-acid
B. Ni-Cd and Lead-acid
C. Ni-MH and Lithium-ion

B. Ni-Cd and Lead-acid

How well did you know this?

Not at all

Perfectly

What is the nominal voltage of a complete aircraft main battery with cells connected in series, and what is the typical voltage of each cell?
A. 12 V with 1.2 V per cell
B. 24 V with 1.2 V per cell
C. 48 V with 2.4 V per cell

B. 24 V with 1.2 V per cell

How well did you know this?

Not at all

Perfectly

What is the voltage of an individual battery cell during charging and discharging?
A. 1.0 V during charging and 1.5 V during discharge
B. 1.5 V during charging and 1.0 V during discharge
C. 1.2 V during charging and 1.2 V during discharge

B. 1.5 V during charging and 1.0 V during discharge

How well did you know this?

Not at all

Perfectly

How can line maintenance personnel check if a nickel-cadmium battery is fully charged?
A. By visually inspecting the battery
B. By monitoring the voltage and current during charging
C. By measuring the battery temperature

B. By monitoring the voltage and current during charging

How well did you know this?

Not at all

Perfectly

What is one of the major problems with batteries?
A. Battery corrosion
B. Thermal Runaway (TR)
C. Overcharging

B. Thermal Runaway (TR)

How well did you know this?

Not at all

Perfectly

What are the two basic methods of charging batteries?
A. Constant Voltage Method and Constant Current Method
B. Rapid Charge Method and Slow Charge Method
C. Quick Charge Method and Full Charge Method

A. Constant Voltage Method and Constant Current Method

How well did you know this?

Not at all

Perfectly

What are the three different DC power sources used for DC generation in modern aircraft?
A. DC battery, External DC power source, and DC generators
B. AC battery, External AC power source, and AC generators
C. Solar panel, Wind turbine, and AC battery

A. DC battery, External DC power source, and DC generators

How well did you know this?

Not at all

Perfectly

What is the purpose of the External Power Unit (EPU) or Ground Power Unit (GPU) in an aircraft?
A. To supply power to the aircraft whilst it is in the air
B. To supply the aircraft with power while it is on the ground
C. To generate emergency power during flight

B. To supply the aircraft with power while it is on the ground

How well did you know this?

Not at all

Perfectly

What is the primary function of a voltage regulator in an aircraft’s electrical system?
A. To generate power for the aircraft’s systems
B. To maintain the generator’s voltage within a set limit automatically
C. To control the battery’s charging rate

B. To maintain the generator’s voltage within a set limit automatically

How well did you know this?

Not at all

Perfectly

DC voltage in an aircraft can be obtained from which of the following sources?
A. DC generators only
B. Batteries and Transformer Rectifier Units (TRU) only
C. DC generators, batteries, and Transformer Rectifier Units (TRU)

C. DC generators, batteries, and Transformer Rectifier Units (TRU)

How well did you know this?

Not at all

Perfectly

TRUs (Transformer Rectifier Units) typically provide which of the following DC voltages on aircraft?
A. 12 Vdc or 24 Vdc
B. 28 Vdc or 14 Vdc
C. 36 Vdc or 18 Vdc

B. 28 Vdc or 14 Vdc

How well did you know this?

Not at all

Perfectly

What is the primary purpose of a Transformer Rectifier Unit (TRU) in an aircraft’s electrical system?
A. To convert DC voltage to AC voltage
B. To convert 115 Vac supplied by the AC generator to a lower DC voltage
C. To increase the DC voltage supplied by the aircraft’s battery

B. To convert 115 Vac supplied by the AC generator to a lower DC voltage

How well did you know this?

Not at all

Perfectly

What is one advantage of parallel electrical systems in aircraft?
A. They provide higher voltage than individual generators
B. They allow for the isolation of a defective generator during flight
C. They increase the fuel efficiency of the aircraft

B. They allow for the isolation of a defective generator during flight

How well did you know this?

Not at all

Perfectly

What is a paralleling bus, or synchronizing bus, used for in aircraft electrical systems?
A. To connect the aircraft’s battery to the power distribution system
B. To connect the generators during flight
C. To monitor the fuel levels during flight

B. To connect the generators during flight

How well did you know this?

Not at all

Perfectly

What happens in the event of a generator failure in a parallel electrical system?
A. The generators are automatically shut down
B. The defective generator is isolated from the system
C. The entire electrical system is powered off

B. The defective generator is isolated from the system

How well did you know this?

Not at all

Perfectly

Why is paralleling of electrical systems in aircraft important?
A. It allows for efficient use of fuel
B. It helps ensure that in case of a generator failure, power is not lost
C. It reduces the weight of the aircraft

B. It helps ensure that in case of a generator failure, power is not lost

How well did you know this?

Not at all

Perfectly

What is the function of the “DC BUS” switching in an aircraft’s electrical system?
A. To switch between AC and DC power
B. To switch the main DC buses into parallel operation
C. To monitor the battery charge levels

B. To switch the main DC buses into parallel operation

How well did you know this?

Not at all

Perfectly

Which of the following are sources of AC power on an aircraft?
a) AC generators, Static inverters, Rotary inverters
b) AC generators, Batteries, Rotary inverters
c) Static inverters, Batteries, Solar panels

a) AC generators, Static inverters, Rotary inverters

How well did you know this?

Not at all

Perfectly

What are the characteristics of the AC electrical power system in modern aircraft? a) Single-phase, 60 Hz, 120 V b) Three-phase, 400 Hz, 115/200 V c) DC power, 24 V

b) Three-phase, 400 Hz, 115/200 V

In a rotating field alternator, which part is stationary and which part rotates? a) Armature rotates, Field is stationary b) Armature is stationary, Field rotates c) Both rotate

b) Armature is stationary, Field rotates

What is the frequency of a generator's alternating output directly proportional to? a) Rotor size b) Rotational speed of the rotor c) Ambient temperature

b) Rotational speed of the rotor

What is the term used when the frequency increases with the rotor's speed in a generator? a) AC Stable b) AC Wild c) AC Fixed

b) AC Wild

What additional factor, besides rotor speed, affects the frequency of a generator's output? a) Rotor size b) The number of pairs of rotating poles c) Generator voltage

b) The number of pairs of rotating poles

Why are most modern aircraft powered by constant frequency systems? a) They are easier to maintain b) They provide a stable and reliable power supply c) They require fewer components

b) They provide a stable and reliable power supply

Why are most modern aircraft powered by constant frequency systems? a) Generator loading decreases with engine speed b) Generator loading increases with engine speed c) Generator loading does not vary with engine speed

c) Generator loading does not vary with engine speed

How are constant speed and frequency achieved in modern aircraft generators? a) By varying the engine speed directly b) By fitting a Constant Speed Drive (CSD) between the engine’s auxiliary gearbox and the generator c) By using a battery backup system

b) By fitting a Constant Speed Drive (CSD) between the engine’s auxiliary gearbox and the generator

What does the Constant Speed Drive (CSD) do with the variable engine speed? a) Converts it into electrical energy b) Adapts it to produce a constant output drive speed c) Increases it to a higher speed

b) Adapts it to produce a constant output drive speed

Why is the output drive from the Constant Speed Drive (CSD) coupled to the generator? a) To maintain constant speed and constant frequency output b) To increase engine speed c) To reduce generator voltage

a) To maintain constant speed and constant frequency output

What does the diagram of a constant frequency system typically show? a) Only the engine components b) A simplified control system and the AC and DC bus bars c) Fuel flow and engine temperature

b) A simplified control system and the AC and DC bus bars

From where does the AC generator obtain its drive in a constant frequency system? a) Engine directly b) Battery c) Constant Speed Drive Unit (CSDU)

c) Constant Speed Drive Unit (CSDU)

What type of system is the Integrated Drive Generator (IDG)? a) An old-fashioned AC power source b) A state-of-the-art means of producing AC electrical power c) A DC power generator

b) A state-of-the-art means of producing AC electrical power

What advantage does the Integrated Drive Generator (IDG) have over traditional systems? a) It separates the generator and CSDU into two units b) It combines the generator and CSDU into one unit, making it lighter and smaller c) It uses more power than traditional systems

b) It combines the generator and CSDU into one unit, making it lighter and smaller

What does each generator in an AC generation system have? a) A single control unit for all generators b) A Generator Control Unit (GCU) for each generator c) No control unit

b) A Generator Control Unit (GCU) for each generator

What are the three main functions of the Generator Control Unit (GCU)? a) Regulation, Protection, Switching b) Generation, Distribution, Storage c) Monitoring, Maintenance, Repair

a) Regulation, Protection, Switching

Which of the following are functions of the Generator Control Unit (GCU)? a) Voltage regulation, current limiting, protection against out-of-tolerance voltages and frequencies, crew alerting b) Fuel management and navigation control c) Engine thrust control and landing gear operation

a) Voltage regulation, current limiting, protection against out-of-tolerance voltages and frequencies, crew alerting

How does the electrical power operate on a typical non-parallel aircraft system? a) As one combined power channel b) As two independent power channels: left and right c) Through a backup battery system only

b) As two independent power channels: left and right

What must stay within very strict limits in a parallel electrical system to ensure proper operation? a) Generator voltages, frequencies, and phase sequences b) Engine speed and fuel flow c) Cabin pressure and temperature

a) Generator voltages, frequencies, and phase sequences

What are the electrical signals from the current transformer used for in an aircraft? a) To control protection circuitry and supply signals to load meters on the overhead panel b) To adjust cabin temperature c) To control engine thrust

a) To control protection circuitry and supply signals to load meters on the overhead panel In the flight deck

What is the typical minimum duration of an aircraft’s emergency electrical power supply? a) 15 minutes b) 30 minutes c) 1 hour

b) 30 minutes

Why is an emergency generator necessary on aircraft operating long routes (EROP)? a) Because there are many landing options b) Because landing quickly may not be possible, requiring extended power backup c) Because it reduces fuel consumption

b) Because landing quickly may not be possible, requiring extended power backup

What is a key requirement for the power source driving the emergency generator? a) It must be connected to the main engines b) It must be independent of the engines c) It must be powered by the aircraft’s battery only

b) It must be independent of the engines

What is an emergency generator called if it is driven directly by a ram air turbine? a) Constant Speed Motor Generator (CSMG) b) Air Driven Generator (ADG) c) Hydraulic Generator

b) Air Driven Generator (ADG)

What is an emergency generator called if it is driven by a hydraulic motor? a) Air Driven Generator (ADG) b) Constant Speed Motor Generator (CSMG) c) Ram Air Turbine Generator

b) Constant Speed Motor Generator (CSMG)

How is emergency power switching controlled during flight? a) Fully manual only b) Fully automatic, with manual override possible c) Fully automatic with no manual option

b) Fully automatic, with manual override possible

Why must all batteries be switched off while the aircraft is parked? a) To save fuel b) To prevent battery discharge by the emergency equipment c) To avoid noise in the cabin

b) To prevent battery discharge by the emergency equipment

What is the name of the part of the distribution that remains powered and is always connected directly to the battery? a) Cold battery bus b) Hot battery bus c) Main power bus

b) Hot battery bus

What are the functions of the Auxiliary Power Unit (APU)? a) Starting the main engines, pre-flight preparation, and serving as an auxiliary power source during flight if the main engine fails b) Only starting the main engines c) Only providing cabin heating

a) Starting the main engines, pre-flight preparation, and serving as an auxiliary power source during flight if the main engine fails

What happens to the spring-biased contacts in a vibrating voltage regulator when the generator voltage is below its predetermined level? a) They open b) They close c) They stay unchanged

b) They close

Where is the generator voltage felt in a vibrating voltage regulator? a) At the field coil b) At the series winding of the voltage regulator coil c) At the battery terminal

b) At the series winding of the voltage regulator coil

What happens when current flows through the series winding and closed voltage regulator contact breaker in a vibrating voltage regulator? a) The output voltage decreases b) The output voltage builds up by energizing the field coil c) The generator shuts down

b) The output voltage builds up by energizing the field coil

What type of voltage regulation system is most common in modern aircraft? a) Vibrating voltage regulators b) Solid-state (transistorised) voltage regulators c) Mechanical voltage regulators

b) Solid-state (transistorised) voltage regulators

is the purpose of busbars in an aircraft electrical system? a) To generate electrical power b) To distribute electrical power and provide a physical connection for circuit breakers c) To regulate voltage levels

b) To distribute electrical power and provide a physical connection for circuit breakers

What type of voltage regulation system is most common in modern aircraft? a) Vibrating voltage regulators b) Solid-state (transistorised) voltage regulators c) Mechanical voltage regulators

b) Solid-state (transistorised) voltage regulators

What is the purpose of busbars in an aircraft electrical system? a) To generate electrical power b) To distribute electrical power and provide a physical connection for circuit breakers c) To regulate voltage levels

b) To distribute electrical power and provide a physical connection for circuit breakers

What materials are busbars typically made from to carry large currents? a) Steel or iron b) Aluminium or copper strips c) Plastic or rubber

b) Aluminium or copper strips

Where are busbars typically found on older aircraft, and what has replaced them on newer generation aircraft? a) Inside engines; replaced by batteries b) Behind circuit breaker panels; replaced by contactors c) In the cockpit; replaced by fuses

b) Behind circuit breaker panels; replaced by contactors

What is the function of an electrical power bus? a) To generate electrical power b) To connect the power source to all electrical consumers using the same type of electrical power c) To regulate engine speed

b) To connect the power source to all electrical consumers using the same type of electrical power

How is power source switching controlled in aircraft electrical systems? a) Only manually b) Only automatically c) Either automatically or manually

c) Either automatically or manually

What are the main components used in power relays for aircraft electrical systems? a) Power relays as switching devices, circuit breakers, and fuses as safety devices b) Batteries and transformers c) Engines and fuel pumps

a) Power relays as switching devices, circuit breakers, and fuses as safety devices

What are the two types of power relays used in aircraft electrical systems? a) Contactor and breaker b) Fuse and resistor c) Transformer and capacitor

a) Contactor and breaker

What is the function of a contactor in an aircraft electrical system? a) To regulate voltage levels b) To use a low-power coil drive circuit to switch higher currents and voltages c) To store electrical energy

b) To use a low-power coil drive circuit to switch higher currents and voltages

What is part of the main AC power distribution? a) The main AC buses b) The fuel system c) The landing gear

a) The main AC buses

What connects the power sources to the buses? a) Power source switching b) Flight controls c) Air conditioning

a) Power source switching

What does bus tie switching do? a) Connects two AC buses b) Starts the engines c) Controls cabin lighting

a) Connects two AC buses

How many main buses does an AC bus have, and what are they called in the three-phase electrical power system? a) One main bus called X b) Three main buses called A, B, and C c) Two main buses called Red and Blue

b) Three main buses called A, B, and C

What must be done before switching any power source on or off on the ground? a) Large loads must be shed or switched off b) The engines must be started c) The cabin lights must be turned on

a) Large loads must be shed or switched off

Why is load shedding important before switching power sources on or off? a) It improves power relay reliability and prevents overload b) It turns on the engines faster c) It cools the cabin air

a) It improves power relay reliability and prevents overload

When does automatic load shedding occur in an aircraft electrical system? a) When the engines start b) When an overload of generators is detected or needs to be prevented c) When the cabin lights turn on

b) When an overload of generators is detected or needs to be prevented

What does an inverter do in an aircraft electrical system? a) Provides AC voltage from DC power sources b) Supplies fuel to the engines c) Powers the landing gear system

a) Provides AC voltage from DC power sources

What AC voltages are typically provided by an inverter on an aircraft, and what is their usual DC supply source? a) 12 Vac or 24 Vac from 14 Vdc b) 26 Vac or 115 Vac from 28 Vdc c) 50 Vac or 100 Vac from 48 Vdc

b) 26 Vac or 115 Vac from 28 Vdc

What is the purpose of a transformer in an electrical system? a) To transform voltages up or down b) To store electrical energy c) To convert DC power to AC power

a) To transform voltages up or down

What is the purpose of a rectifier in an aircraft electrical system? a) To convert DC voltages to AC voltages b) To convert AC voltages to DC voltages c) To step up or step down voltages

b) To convert AC voltages to DC voltages

How do rectifiers usually convert AC voltages to DC voltages? a) Using mechanical switches b) Using solid-state technology like diodes c) Using transformers

b) Using solid-state technology like diodes

What are the two main types of rectifiers? a) Step-up and step-down rectifiers b) Half wave and full wave rectifiers c) Single-phase and three-phase rectifiers

b) Half wave and full wave rectifiers

What is a Transformer Rectifier Unit (TRU)? a) A combination of transformer and rectifier in one unit b) A combination of inverter and rectifier in one unit c) A combination of generator and battery in one unit

a) A combination of transformer and rectifier in one unit

What does an inverter do in an aircraft electrical system? a) Converts DC to AC b) Converts AC to DC c) Steps up voltage

a) Converts DC to AC

What are the two basic types of inverters? a) Rotary and static inverters b) Step-up and step-down inverters c) Half wave and full wave inverters

a) Rotary and static inverters

What does a solid-state inverter consist of? a) A mechanical motor and transformer b) A 400 Hz sinusoidal oscillator and a transformer c) A battery and rectifier

b) A 400 Hz sinusoidal oscillator and a transformer

What current sensing devices are used to protect electrical systems? a) Fuses and circuit breakers b) Transformers and inverters c) Generators and batteries

a) Fuses and circuit breakers

What is the purpose of fuses and circuit breakers in electrical systems? a) To prevent currents higher than the wire’s maximum allowed b) To increase voltage in the system c) To convert AC to DC

a) To prevent currents higher than the wire’s maximum allowed

Which part of the electrical system is NOT protected by fuses or circuit breakers? a) Generator feeder lines b) Lighting circuits c) Passenger cabin power outlets

a) Generator feeder lines

What protects the generator feeder lines if not fuses or circuit breakers? a) Manual switches b) Electronic circuits of the Generator Control Unit (GCU) c) Mechanical relays

b) Electronic circuits of the Generator Control Unit (GCU)

What is a fuse mainly made of in overcurrent protection? a) A metal strip with a smaller cross-section than the wire it protects b) A plastic strip with the same cross-section as the wire c) A ceramic piece

a) A metal strip with a smaller cross-section than the wire it protects

What must be done if a fuse is blown? a) It must be replaced after repairing the affected circuit b) It can be reused immediately c) It must be bypassed

a) It must be replaced after repairing the affected circuit

What is a major advantage of circuit breakers compared to fuses? a) They can usually be reset after a fault b) They are cheaper to replace c) They protect against voltage drops

a) They can usually be reset after a fault

What are two advantages of circuit breakers compared to fuses? a) They can be reset quickly and act as manual on-off switches b) They are cheaper and more compact c) They increase voltage and current

a) They can be reset quickly and act as manual on-off switches

Why does the location of circuit breakers depend on the wire or consumer they protect? a) To minimise wire length b) To maximise wire length c) To make maintenance harder

a) To minimise wire length

What was the old common practice when a circuit breaker ‘popped’? a) Count to three and reset repeatedly b) Replace the circuit breaker immediately c) Ignore it and continue operation

a) Count to three and reset repeatedly

What are the two most common types of circuit breakers? a) Thermal and magnetic (or electromagnetic) b) Hydraulic and pneumatic c) Solid-state and mechanical

a) Thermal and magnetic (or electromagnetic)

What is the customary practice when circuit breakers are tripped for servicing? a) They are 'gagged' on the circuit breaker panel b) They are removed completely c) They are ignored and left as is

a) They are 'gagged' on the circuit breaker panel

What is the name of the electronic circuit breakers used in the A380 for currents up to 15 A? a) Solid State Power Controller (SSPC) b) Thermal Circuit Breaker c) Magnetic Circuit Breaker

a) Solid State Power Controller (SSPC)

What does the power selector switch prevent the GPU from doing? a) Connecting to the battery bus bar and charging the battery directly b) Starting the engines c) Supplying power to the cabin lights

a) Connecting to the battery bus bar and charging the battery directly

What is the function of the small pins in the AC external power receptacle? a) To ensure the three-phase and neutral load-bearing pins are open circuited before disconnection, preventing arcing b) To supply power to the cabin lighting c) To charge the aircraft battery directly

a) To ensure the three-phase and neutral load-bearing pins are open circuited before disconnection, preventing arcing

What must be checked during the inspection of ground power connectors before every connection? a) Damage, cracks, looseness, bends, discolouration, corrosion, and pitting b) Only the power output c) Only the connection size

a) Damage, cracks, looseness, bends, discolouration, corrosion, and pitting

11.6 Electrical Power Flashcards

(100 cards)