11.6 Electrical Power Flashcards by Dylan Sinclair

What are the two main subsystems of the aircraft electrical power system?
A) Power and Control
B) Generation and Distribution
C) Storage and Monitoring

B) Generation and Distribution

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Which two sources provide electrical power on the ground?
A) Engine generators and TRUs
B) Batteries and APU
C) APU and GPU

C) APU and GPU

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Which of the following is NOT one of the three DC power sources used for generation?
A) AC alternator
B) DC battery
C) DC generators

A) AC alternator

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What are two typical uses for the aircraft battery system?
A) Flight data storage and lighting
B) Emergency power and APU start
C) Cabin entertainment and flight control

B) Emergency power and APU start

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In an emergency, how long must the battery supply electrical power to all consumers?
A) 10 minutes
B) 20 minutes
C) 30 minutes

C) 30 minutes

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What are the two common types of main aircraft batteries?
A) Ni-Cd and Lithium-ion
B) Ni-Cd and Lead-acid
C) Lead-acid and Gel-cell

B) Ni-Cd and Lead-acid

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What is the nominal voltage of a fully assembled aircraft battery made of cells in series?
A) 12V
B) 24V
C) 36V

B) 24V

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What voltage does a battery cell typically reach when fully charged?
A) 1.2V
B) 1.5V
C) 2.0V

B) 1.5V

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What is a major safety concern associated with batteries?
A) Static discharge
B) Electromagnetic interference
C) Thermal runaway

C) Thermal runaway

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Which method is NOT used to charge nickel-cadmium batteries?
A) Constant voltage
B) Constant current
C) Pulse discharge

C) Pulse discharge

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How can line maintenance personnel monitor the charge level of Ni-Cd batteries?
A) By weighing the battery
B) By checking voltage and current during charging
C) By using infrared scanning

B) By checking voltage and current during charging

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What voltage is used from the DC distribution to recharge batteries via TRUs?
A) 12V
B) 24V
C) 28V

C) 28V

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Which of the following is NOT one of the three possible DC power sources used in modern aircraft?
A) DC battery
B) DC inverter
C) DC generator

B) DC inverter

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What is the primary role of the Ground Power Unit (GPU) or External Power Unit (EPU)?
A) To regulate onboard battery voltage
B) To supply power to the aircraft while on the ground
C) To boost engine performance during takeoff

B) To supply power to the aircraft while on the ground

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What component is responsible for automatically maintaining a generator’s voltage within a set limit?
A) Power control unit
B) Load shed relay
C) Voltage regulator

C) Voltage regulator

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Which unit converts AC voltage from the generator into DC voltage?
A) Inverter
B) Transformer Rectifier Unit (TRU)
C) Voltage regulator

B) Transformer Rectifier Unit (TRU)

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What are the typical DC output voltages provided by TRUs?
A) 115 Vdc and 230 Vdc
B) 28 Vdc and 14 Vdc
C) 24 Vdc and 48 Vdc

B) 28 Vdc and 14 Vdc

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What is the main function of a Transformer Rectifier Unit (TRU)?
A) To convert DC to AC power
B) To rectify and transform AC voltage to DC at a usable level
C) To synchronize generator frequencies

B) To rectify and transform AC voltage to DC at a usable level

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What is one key advantage of parallel DC systems in aircraft?
A) They are lighter in weight
B) They reduce the voltage requirement
C) They allow buses to remain connected if a generator fails

C) They allow buses to remain connected if a generator fails

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What is the purpose of the synchronising or sync bus in a DC system?
A) To increase generator voltage output
B) To isolate the TRUs
C) To connect the generators during flight

C) To connect the generators during flight

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How are the main DC buses normally switched into parallel operation?
A) Automatically by the GPU
B) Through “DC BUS” switching
C) Using the inverter relay

B) Through “DC BUS” switching

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What are the primary sources of AC power on an aircraft?
A) AC batteries, solar panels, fuel cells
B) Static inverters, rotary inverters, AC generators
C) Fuel pumps, CSDs, hydraulic motors

B) Static inverters, rotary inverters, AC generators

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What are the standard voltage and frequency values for modern aircraft AC systems?
A) 230V, 60Hz
B) 115V/200V, 400Hz, three-phase
C) 28V, 400Hz, single-phase

B) 115V/200V, 400Hz, three-phase

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In a rotating field alternator, what remains stationary?
A) Field
B) Rotor
C) Armature

C) Armature

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The frequency of a generator’s output is directly proportional to: A) Voltage output B) Rotor speed C) Armature resistance

B) Rotor speed

Why are constant frequency systems commonly used in modern aircraft? A) They are more compatible with hydraulic systems B) Generator loading changes with engine speed C) Induction motors operate at a nearly constant speed

C) Induction motors operate at a nearly constant speed

What is the function of a Constant Speed Drive (CSD)? A) It reduces engine torque B) It adapts variable engine speed to maintain constant generator speed C) It regulates the generator voltage

B) It adapts variable engine speed to maintain constant generator speed

What does an Integrated Drive Generator (IDG) combine? A) A battery and generator B) A transformer and inverter C) A generator and Constant Speed Drive Unit (CSDU)

C) A generator and Constant Speed Drive Unit (CSDU)

What are the main functions of a Generator Control Unit (GCU)? A) Lighting control and fuel balancing B) Regulation, protection, and switching C) Cabin pressurization and altitude alerting

B) Regulation, protection, and switching

Which of the following is NOT a typical function of a GCU? A) Voltage regulation B) Thermal runaway prevention C) Frequency protection

B) Thermal runaway prevention

In a typical non-parallel AC power system, how does the electrical power operate? A) From a single generator feeding both sides B) As two independent power channels C) As a DC-linked loop

B) As two independent power channels

What is the maximum frequency difference allowed across the bus tie breaker for paralleling? A) 10 Hz B) 6 Hz C) 2 Hz

B) 6 Hz

What is the purpose of a Current Transformer (CT) in the AC system? A) To cool the generator coils B) To provide current sensing signals for protection and load meters C) To transform AC voltage into DC voltage

B) To provide current sensing signals for protection and load meters

What is the required minimum duration that emergency power must be available to allow the captain to land the aircraft safely? A) 15 minutes B) 30 minutes C) 60 minutes

B) 30 minutes

What is the term used for aircraft operating on long routes without quick landing options? A) Long Range Operations (LRO) B) Global Route Navigation (GRN) C) Extended Range Operation (EROP)

C) Extended Range Operation (EROP)

What drives an Air Driven Generator (ADG)? A) Engine turbine B) Ram air turbine C) Auxiliary power unit

B) Ram air turbine

What is a Constant Speed Motor Generator (CSMG) driven by? A) Electric motor B) Hydraulic motor C) Engine gearbox

B) Hydraulic motor

How is emergency power switching managed during flight? A) Manually only B) Automatically only C) Fully automatic, but manual switching is also possible

C) Fully automatic, but manual switching is also possible

Why must all batteries be switched off while the aircraft is parked? A) To allow system recalibration B) To prevent power surges C) To prevent discharge by emergency equipment

C) To prevent discharge by emergency equipment

What part of the aircraft electrical system remains powered while parked due to its direct battery connection? A) Auxiliary power bus B) Generator control bus C) Hot battery bus

C) Hot battery bus

Which of the following is a function of the Auxiliary Power Unit (APU) during flight? A) Cabin pressurization B) Backup power if the main engine fails C) Engine lubrication

B) Backup power if the main engine fails

What is a Ram Air Turbine (RAT) used for? A) Cabin temperature control B) Fuel distribution C) Emergency power generation

C) Emergency power generation

What does HMDG stand for in the context of emergency power systems? A) Hybrid Manual Drive Gear B) Hydraulic Motor-Driven Generator C) High-Mass Distribution Grid

B) Hydraulic Motor-Driven Generator

What happens when the generator voltage is below its predetermined level in a vibrating voltage regulator? A) The contacts remain open to prevent current flow B) The spring-based contacts close to allow voltage buildup C) The generator shuts down automatically

B) The spring-based contacts close to allow voltage buildup

In a vibrating voltage regulator, where does the generator voltage flow first when the contacts are closed? A) To the output terminals B) To the field coil directly C) Through the series winding of the voltage regulator coil

C) Through the series winding of the voltage regulator coil

What is the main function of the current flowing through the field coil in a vibrating voltage regulator? A) To reduce electrical noise B) To prevent overheating C) To enable the output voltage to build up

C) To enable the output voltage to build up

What is the common name for modern voltage regulation systems using transistors? A) Mechanical voltage regulators B) Vibrating contact regulators C) Solid-state voltage regulators

C) Solid-state voltage regulators

What component type is typically used in modern voltage regulators instead of spring-based contacts? A) Diodes B) Transistors C) Relays

B) Transistors

What is the primary purpose of barbars in an aircraft electrical system? A) To regulate generator voltage B) To provide wireless data transmission C) To distribute electrical power and connect circuit breakers

C) To distribute electrical power and connect circuit breakers

What materials are typically used to make barbars? A) Plastic or fiberglass B) Steel or rubber C) Aluminium or copper

C) Aluminium or copper

What does an essential bus connect? A) Only passenger comfort systems B) Power source to essential safe flight systems C) All non-essential aircraft systems

B) Power source to essential safe flight systems

How is power source switching controlled in aircraft systems? A) Only manually by ground crew B) Either automatically or manually C) Only by an emergency generator

B) Either automatically or manually

Which components are primarily used as switching devices in power distribution systems? A) Diodes B) Power relays C) Battery isolators

B) Power relays

What is another name for a type of power relay? A) Capacitor B) Contactor C) Converter

B) Contactor

How do contactors operate? A) They require manual switching B) They are driven by mechanical levers C) They use a low-power coil to switch higher currents and voltages

C) They use a low-power coil to switch higher currents and voltages

What does the main AC power distribution system include? A) Solar panels and batteries only B) AC buses, power source switching, and bus tie switching C) Fuel cells and DC inverters

B) AC buses, power source switching, and bus tie switching

What does each AC bus consist of in a three-phase power system? A) A single phase power line B) Random phase outputs C) Three main buses for phases A, B, and C

C) Three main buses for phases A, B, and C

Why must large electrical loads be shed before switching a power source on or off on the ground? A) To conserve fuel B) To improve relay reliability and avoid power overload C) To allow batteries to cool down

B) To improve relay reliability and avoid power overload

When is automatic load shedding activated? A) During takeoff B) When passengers use in-flight Wi-Fi C) When generator overload is detected or must be prevented

C) When generator overload is detected or must be prevented

What is the primary function of an inverter in an aircraft? A) To store electrical energy for emergency use B) To convert AC power into DC power C) To provide AC voltage from DC power sources

C) To provide AC voltage from DC power sources

What AC voltages are typically supplied by aircraft inverters? A) 12 Vac or 230 Vac B) 26 Vac or 115 Vac C) 14 Vac or 400 Vac

B) 26 Vac or 115 Vac

What type of power input do aircraft inverters typically use? A) 115 Vac B) 400 Hz AC C) 28 Vdc

C) 28 Vdc

What is the purpose of a transformer? A) To store excess electrical energy B) To transform voltages up or down C) To filter out electrical noise

B) To transform voltages up or down

What type of transformer increases voltage output? A) Step-down transformer B) Step-up transformer C) Isolation transformer

B) Step-up transformer

What do rectifiers do in an aircraft electrical system? A) Convert DC to AC B) Store electrical energy C) Convert AC voltages to DC voltages

C) Convert AC voltages to DC voltages

Which technology is commonly used in rectifiers for converting AC to DC? A) Resistors B) Inductors C) Diodes

C) Diodes

What are the two types of rectifiers? A) Step and phase rectifiers B) Full wave and half wave rectifiers C) Low and high frequency rectifiers

B) Full wave and half wave rectifiers

What is a Transformer Rectifier Unit (TRU)? A) A backup battery unit B) A combination of inverter and transformer C) A combination of transformer and rectifier

C) A combination of transformer and rectifier

Which of the following is a type of inverter? A) Oscillating inverter B) Pulse inverter C) Rotary inverter

C) Rotary inverter

What does a solid-state inverter include? A) Vacuum tubes and switches B) 400 Hz sinusoidal oscillator and a transformer C) Manual voltage regulator and rectifier

B) 400 Hz sinusoidal oscillator and a transformer

Which of the following is not protected by fuses or circuit breakers? A) Generator feeder lines B) Cabin lighting circuits C) Avionics systems

A) Generator feeder lines

What protects generator feeder lines instead of fuses or circuit breakers? A) Thermal sensors B) Manual switches C) Electronic circuits of the GCU

C) Electronic circuits of the GCU

What is the main function of a fuse in an aircraft electrical system? A) To store excess energy B) To prevent overvoltage C) To protect against overcurrent by melting

C) To protect against overcurrent by melting

What must be done when a fuse blows in an aircraft system? A) Reset it immediately B) Wait for it to cool down C) Replace it after fixing the fault

C) Replace it after fixing the fault

Which is a key advantage of circuit breakers over fuses? A) They are more sensitive B) They can be reset after fault correction C) They cost less

B) They can be reset after fault correction

Which of the following can also serve as a manual on/off switch? A) Fuse B) Thermal relay C) Circuit breaker

C) Circuit breaker

Why is the location of circuit breakers important in aircraft design? A) To protect the passengers B) To minimise wire length C) To reduce system weight

B) To minimise wire length

Which of the following is not a type of physical circuit breaker? A) Push/Pull Pop Out B) Switch Type C) Smart Touchscreen

C) Smart Touchscreen

What are the two most common types of circuit breakers? A) Hydraulic and pneumatic B) Thermal and magnetic C) Manual and automatic

B) Thermal and magnetic

What is a virtual circuit breaker? A) A fuse embedded in the circuit board B) A computer-controlled breaker that opens a relay C) A circuit breaker activated by voice command

B) A computer-controlled breaker that opens a relay

What does SSPC stand for in modern aircraft? A) Solid State Power Converter B) Smart Safety Power Circuit C) Solid State Power Controller

C) Solid State Power Controller

On which aircraft model would you typically find electronic circuit breakers like SSPCs for nominal currents up to 15A? A) Boeing 737 B) Airbus A380 C) Cessna 172

B) Airbus A380

What types of external ground power are commonly supplied to an aircraft? A) 28 Vac and 48 Vdc B) 115 Vac and 12/28 Vdc C) 400 Vac and 24 Vdc

B) 115 Vac and 12/28 Vdc

What is the purpose of the small pins in the AC external power connector? A) To provide an additional ground B) To increase power flow C) To ensure the load-bearing pins are open circuited before disconnection

C) To ensure the load-bearing pins are open circuited before disconnection

Why must load-bearing pins in the AC plug be open circuited before disconnection? A) To reduce frequency fluctuations B) To prevent voltage drop C) To prevent arcing

C) To prevent arcing

What must be inspected before every connection of ground power to the aircraft? A) The battery compartment B) The aircraft power switch C) The AC or DC aircraft connection

C) The AC or DC aircraft connection

Which of the following is not part of the required inspection criteria for ground power connectors? A) Voltage drop B) Cracks C) Corrosion

A) Voltage drop

Which of the following is a potential defect to look for during inspection of ground power connectors? A) Magnetic interference B) Loose pins C) High pressure

B) Loose pins

11.6 Electrical Power Flashcards

(88 cards)