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AT354 Hawker Ground > Electrical Power Systems > Flashcards

Electrical Power Systems Flashcards

1
Q

The Hawker is a primarily ___ aircraft.

A

DC

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2
Q

HS-125 Electrical Bus Codes: What does P, X, and S signify?

A

P: DC power
X: AC power
S: Split-bus power

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3
Q

What bus does the APU power?

A

The PS2 bus

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4
Q

What provides power for some avionics and navigation equipment?

A

Two inverters providing 115-volt AC power

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5
Q

What powers windshield heat, windscreen heat, and stall vane heat?

A

Two-engine driven alternators

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6
Q

What do the alternators power?

A

Windshield heat, windscreen heat, stall vane heat

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7
Q

Where are most of the electrical components located onboard?

A

Aft equipment bay

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8
Q

Where is the one location besides the aft equipment bay electrical components may be found onboard?

A

The main distribution panel in the vestibule area

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9
Q

How is power distributed onboard?

A

Through a split-bus system controlled via circuit breakers

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10
Q

Where are the circuit breaker panels located?

A

One panel behind the head of the SIC, one larger panel in vestibule, and additional panels in the aft equipment bay

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11
Q

What drives the electrical system onboard?

A

Two 28-volt, 300-amp (continuous, 400-amps for two minutes) starter-generators (with an additional starter-generator on the APU)

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12
Q

What is the battery arrangement onboard?

A

Two main batteries (24-volt, 28 amp-hour lead-acid) and four additional smaller batteries

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13
Q

Where are the batteries located and what are their function?

A

Aft equipment bay, primarily used to start APU/engines and provide emergency power

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14
Q

What items are on the Hot Battery Bus? (VREF)

A

Voltmeter
Rear Equipment Bay Light
Entry/Vestibule Lights
reFueling Panel

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15
Q

What are the batteries directly connected to?

A

The PE bus

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16
Q

BATT switch ON:

A

Uses power from BATT 1 to close emergency contactors, connecting BATT 1 and BATT 2 to PE bus

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17
Q

BATT switch EMERGENCY:

A

Closes emergency contactors, powers PE bus, batteries do NOT charge

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18
Q

Why do we need fully charged batteries prior to takeoff?

A

Guarantees the minimum 30 minutes of electrical power in the case of an emergency

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19
Q

What does the ISOLATE switch do?

A

Isolates the respective batteries from the system - it will neither be charged nor power anything

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20
Q

EXT PWR switch ON:

A

Allows ground power units to power the electrical system

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21
Q

EXT BATT switch CHG ON:

A

Allows onboard batteries to be charged from external ground power if available and EXT PWR is ON

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22
Q

What is the voltmeter used for?

A

Allows monitoring of voltage on selected battery or bus

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23
Q

How can you change what system you are monitoring on the voltmeter, and what systems/buses can be monitored?

A

Rotary switch under voltmeter - allows monitoring of BATT 1, BATT 2, PS1 bus, PS2 bus, PE bus, as well as an XFER position to check voltage of the 4 additional smaller batteries. Typically left in PE switch position.

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24
Q

What is located on each engine and the APU, providing DC power to the aircraft?

A

A 28-volt, 300-amp starter-generator

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25
Q

How are the starter-generators cooled?

A

Ram air inlets on the cowling for each engine

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26
Q

How do starter-generators function?

A

Initially act as starters (for the engines and APU), then automatically switches to acting as a generator

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27
Q

When does a starter-generator switchover to generating power?

A

Around 42.5% N2

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28
Q

What are Generator Control Units? (GCU)

A

Provide output stabilization and load equalization - generators share the load through a bus-tie, and the GCUs ensure that the generators are carrying their half of the load and providing proper output

29
Q

What are the protections offered by a GCU?

A

Protection against reverse current flow, overvoltage, overexcitation (normal voltage is 28v)

30
Q

How do GCUs control generators?

A

Directly controlling Generator Line Contactors (GLC), which allows power from the generator into the aircraft electrical system and stabilizes bus bars at 28.5-volts

31
Q

What are bus-tie contactors?

A

Provides connection of the main bus bars (PS1 and PS2), allows load sharing to take place

32
Q

Are bus-tie contactors automatic?

A

NO, must be manually closed via the spring-loaded BUS TIE switch, when first starting the aircraft the bus-tie must be manually latched every time (however opens automatically)

33
Q

When would the bus-tie contactors automatically open?

A

In case of self-preservation due to under or over-voltage

34
Q

What voltage would cause the bus-tie contactor to open?

A

When voltage reaches 29.5±0.5 volts or 24.5±0.5 volts

35
Q

What allows for load sharing between the main bus bars?

A

An equalizing circuit

36
Q

Generator Close Switches are located where?

A

The electrical services panel

37
Q

Generator Control Switch to CLOSE:

A

Connects the respective generator to electrical system IF the GCU allows it

38
Q

Generator Control Switch to TRIP:

A

Opens circuit, removing generator power from system; may happen automatically for self-preservation, may be moved manually to disconnect generators if needed

39
Q

What are the ammeters for?

A

Dual purpose (may indicate loads on two different things), indicate load on respective generators for engines, range from 0-450 amps

40
Q

Where is the ammeter for the APU generator?

A

APU Control Panel

41
Q

What does the BATT pushbutton do when pressed?

A

Connects ammeters to batteries to show the charge rate of the batteries

42
Q

What should the charge rate of the batteries be less than prior to takeoff?

A

The charge rate of the batteries should be below 20 amps prior to takeoff

43
Q

What is shown if the BATT pushbutton is not pressed down when checking amperage?

A

The system or generator amperage is read instead

44
Q

What does the 0-40 pushbutton do when pressed?

A

Rescales the ammeter from 0-450 amps to 0-40 amps for easier reading when checking battery amperage

45
Q

How long does it typically take after engine start for the batteries to have an acceptable charge rate for takeoff?

A

Around 5-7 minutes after engine start

46
Q

Where is the external power port located on the Hawker?

A

Right side fuselage, underneath the engine pylon

47
Q

What connector is used for Ground Power Units?

A

Standard 3-pin, 28 volt DC-power receptacle

48
Q

If using a GPU for engine start, what are the limitations of the GPU?

A

The GPU output capability must be 42kW (with a short term capability of 28-volts, 1500-amps), and a current limiter rated at 1,100-amps

49
Q

What GPU is capable of powering the onboard systems?

A

A standard 28-volt battery cart

50
Q

What happens if you attempt engine start with too weak of a power cart?

A

May damage electrical system onboard

51
Q

In the cockpit, how is GPU power turned on and controlled?

A

Only the EXT PWR switched to ON - BATT switch does not need to be ON for electrical power to be supplied

52
Q

How is AC power supplied onboard?

A

Two inverters in aft equipment bay - single-phase, 115-volt, 400Hz AC powering avionics and some navigation equipment

53
Q

How do the inverters power the XS buses?

A

INV 1 normally powers XS1, INV 2 normally powers XS2, one inverter can power BOTH XS1 and XS2

54
Q

How does the distribution of AC power work?

A

Automatic distribution, INV 1/2 switches provide manual control of inverters

55
Q

How are the inverters started?

A

INV 1/2 switch must be held momentarily in START position (spring-loaded switch)

56
Q

Maximum Battery Amps Before Takeoff (B1 and B2)

A

20 amps

57
Q

Starter Limits

A

30 seconds on, 1 minute off. 30 seconds on, 1 minute off. 30 seconds on, 30 minutes off.

58
Q

What is the maximum continuous generator load?

A

300-amps (transient load of 400-amps is permitted for two minutes maximum), active monitoring required

59
Q

Can you reset tripped circuit breakers?

A

NO, unless deemed necessary for the safety of flight. If a reset is followed through with, only ONE attempt is allowed

60
Q

What is the minimum battery voltage?

A

23 volts

61
Q

What does a WHITE circuit breaker mean?

A

Unswitched PE function

62
Q

What does a RED circuit breaker mean?

A

Related to the fire suppression system

63
Q

What does a YELLOW circuit breaker mean?

A

Electric Pitch Trim

64
Q

The batteries will maintain essential service during a dual generator failure for:

A

30 minutes maximum

65
Q

When a generator is offline and the GEN FAIL and ELECT ^ annunciators are illuminated, the generator can be reinstated by:

A

Positioning the GEN switch to CLOSE for five seconds then releasing it

66
Q

The battery-charging rate can be monitored by:

A

Depressing the BATT ammeter pushbutton

67
Q

For engine starting, the ground power unit must produce

A

28 volts, 1,500 amps with 1,100-amp current limiter

68
Q

Circuit breakers protecting unstitched PE circuits are marked to ease isolation in the event of smoke or fire with:

A

A white background

69
Q

When either the BATT 1 CNTCTR or BATT 2 CNTCTR annunciator illuminates, it indicates that the respective:

A

Battery contactor or emergency contractor is open

AT354 Hawker Ground (10 decks)

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