A220 > ELECTRICAL SYSTEM > Flashcards

ELECTRICAL SYSTEM Flashcards

(45 cards)

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1
Q

Where can the aircraft receive its power from?

A

Variable Frequency Generators (VFG)
APU Generator
External AC Power
Ram Air Turbine (RAT)

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2
Q

Variable Frequency Generator (VFG)

A

Two VFGs, mounted on the accessory gearbox.
Supplies 115VAC. Rated to 75kVA continuous. 112.5kVA for 5mins. 150kVA for 5sec.
Contains a Permanent Magnet Generator (PMG), which supplies power to a GCU and an Over-voltage Protection Unit
Lubricating oil for the VFG is cooled by a dedicated air/oil cooler
VFGs controlled by L GEN & R GEN switches

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3
Q

Generator Control Unit (GCU)

A

Regulates VFG voltage
Connects or disconnects the VFG to the main AC busses
Protects the electrical circuits from generator faults
Supplies status information to the Bus Power Control Units (BPCUs)
Primary power for the GCU is the associated PMG, backed up by aircraft DC power

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4
Q

Over-voltage Protection Unit (OPU)

A

Is an additional independent backup to the GCU over-voltage protection
Electrically disconnects the VFG if it produces excessive voltage and the GCU has not acted
PMG powers the OPU

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5
Q

APU Generator

A

115 VAC, VFG mounted on the APU accessory gearbox.
Rated to 75 kVA for continuous up to FL365. 58 kVA at FL410

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6
Q

APU Generator Control Unit (AGCU)

A

Regulates the APU generator voltage
Connects or disconnects the APU generator to the aircraft busses
Protects the electrical channel from APU generator faults
Supplies status information to the Bus Power Control Units (BPCUs)
Primary power is the APU PMG, backed up by aircraft DC power

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7
Q

External AC Power

A

Can supply AC power in two different modes:
Ground service mode
External power mode

When connected, checked for frequency, voltage, & phase.

In ground service mode, AC BUS 1, AC BUS 2, & DC BUS 1 are powered

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8
Q

Which busses are always powered?

A

DC EMER BUS and BATT DIR BUS

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9
Q

Which bus is not shown on ELEC synoptic page?

A

BATT DIR BUS

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10
Q

Ram Air Turbine (RAT)

A

If there is a total loss of AC power, RAT deploys automatically and supplies emergency AC power and hydraulics.
115 VAC, rated at 10 kVA.
Air cooled
Also drives a hydraulic pump

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11
Q

Which busses are supplied by the RAT generator?

A

AC ESS BUS, which powers Electrical Power Center 3 (EPC 3)
DC ESS 3 bus through TRU 3

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12
Q

At what aircraft speed will the RAT supply electrical and hydraulic power?

A

148 knots or more for electrical power
115 knots for hydraulic power

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13
Q

What busses are the batteries connect to?

A

DC ESS 1 & DC ESS 2 busses. All three DC ESS busses are connected in parallel

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14
Q

What happens if a VFG is recovered while RAT is deployed?

A

The VFG will supply the entire electrical system except for:
AC ESS & DC ESS 3 busses. RAT powers these.

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15
Q

How is DC power supplied?

A

Transformer Rectifier Units (TRUs)
Nickel-Cadmium (NiCad) batteries
Battery chargers

DC power generated by two Fly-By-Wire Power Converters (FBWPCs) supplies the Electronic Flight Control System (EFCS)

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16
Q

Transformer Rectifier Units (TRU)

A

3 TRUs.
Primary source of DC power
Rated at 350 amperes
Receives power from AC busses, converts it to 28 VDC and distributes it to the DC busses

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17
Q

Batteries

A

2 24 VDC NiCads
Rated at 42 ampere-hours

Supplies power to:
BATT DIR busses at all times
DC EMER bus at all times
DC ESS busses when BATT selector is in AUTO and TRUs are not functioning
Electric brakes when all other DC sources are not available

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18
Q

What happens if only batteries are supplying power?

A

After 5 minutes, the BATT DISCHARGING caution message is displayed &
A horn sounds until AC power is available, or batteries are switched off

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19
Q

Fly-By-Wire power generation and FADEC power

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A

Two PMAGs, installed on the accessory gearbox. Supplies dedicated AC power to 2 FBWPCs and the EEC of each FADEC
Converts AC to DC and supplies dedicated DC power to FBW system as an alternate source when DC BUS is not available

20
Q

When will the DC EMER bus show on ELEC synoptic page?

Study These Flashcards
A

When it is not powered

21
Q

What do the BATT 1 & BATT 2 switches do?

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A

Allows the BPCU to connect the BATT DIR bus to its corresponding DC ESS
Allows the battery chargers to operate if AC power is available

AUTO position: the BATT DIR bus will power the corresponding DC ESS bus until the DC ESS bus receives power from a TRU

22
Q

APU GEN Switch

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A

FAIL: APU GCU removes generator from the bus due to a fault

23
Q

CABIN PWR guarded switch

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A

Deactivates electrical loads from:
Flight compartment outlets
Cabin systems, such as, galleys and in-flight entertainment systems

Used to isolate sources of smoke in the cabin

24
Q

What happens when you push the RAT GEN switch with the RAT deployed?

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A

RAT GCU will reset

25
L DISC & R DISC guarded switch
Allows crew to disconnect the generator shaft from engine gearbox cannot be reset in-flight OIL: low oil pressure or high oil temperature Engine VFG high oil temperature has two threshold: When the first threshold is reached, the amber OIL light come on When the second higher temperature limit is reached, the VFG automatically disconnects from the engine accessory gearbox
26
Cockpit Voice Recorder
Records all voice, digital comms, & aural alerts Starts recording when beacons or strobes On or weight off wheels Stops recording when lights off plus 10mins Records last 2 hours
27
How long will the Under Water Beacon last?
90 days
28
What type of power does the aircraft use?
Both 115 VAC and 28 VDC
29
PMAG
PMAG supplies power to the EEC and is the alternative power supply to the FBWPC. FBWPC use the DC BUS as the primary source of power and BATT DIR BUS as a transition source.
30
What do the BPCUs do?
The BPCUs route AC power from the available power sources (VFG, APU, or EXT PWR) to their respective AC busses, TRUs and DC busses. The BPCUs control AC and DC line contactors and bus tie contactor. This enables automatic reconfiguration.
31
Load shedding
Seven groups. Not required for continued safe flight. Groups 1 & 2- galley equipment Group 3- in-flight entertainment Group 4- lighting Groups 5,6,7- DC CBs designed to unload the TRUs
32
BUS ISOL switch
Controls automatic EPC reconfiguration of line and bus tie contactors (e.g. during smoke isolation procedures).
33
BUS ISOL AUTO
Reconfigures electrical routing as required.
34
BUS ISOL MAIN
Inhibits auto reconfiguration in EPC 1 and EPC 2. AC busses can only be powered by their on-side VFG.
35
BUS ISOL ESS
Inhibits automatic reconfiguration in EPC 3. Only RAT can power the ACC ESS BUS.
36
Cabin PWR switch
Deactivates electrical loads from flight compartment outlets and selected cabin systems to isolate sources of smoke in the cabin. (Galleys and in-flight entertainment systems).
37
Why is the CABIN PWR switch guarded?
To prevent confusion or inadvertent activation during smoke isolation procedures.
38
RAT GEN switch
Manually deploys the RAT
39
What happens if you press the RAT GEN switch while the RAT is deployed?
The RAT GCU will reset.
40
BATT 1 and BATT 2 switches
Enables the Bus Power Control Unit to connect the BATT DIR bus to its corresponding DC ESS bus until the DC ESS bus receives power from a TRU. Also enables the battery charger to operate if AC power is available.
41
L GEN and R GEN switches
Connects or disconnects the associated VFG. FAIL light indicates generator fault or failure. GCU takes VFG offline.
42
L/R GEN switches OFF
Illuminated when the GEN switch is selected while the engine is running. Will not be illuminated if the engine is shutdown.
43
EXT PWR switch
AVAIL- when appropriate external AC power is connected IN USE- when external power is in use. If an engine VFG or APU VFG is available, the aircraft load will be shared.
44
APU GEN switch
Connects or disconnects the APU generator. FAIL- AGCU removes the generator from the bus due to a fault.
45
L DISC and R DISC
Enables flight crew to disconnect generator shaft from engine gearbox. Cannot be reconnected in flight. OIL- Low oil pressure or high oil temperature. (HOTLOP). DISC- generator is disconnected from the engine gearbox. Two thresholds for high oil temperature. First threshold- OIL light comes on. Higher threshold limit- VFG automatically disconnects from gearbox.
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