Electrical Flashcards
(107 cards)
1
Q
How many independent electrical systems are on the airplane? Why?
ASM 6.1.1
A
- 2 independent networks
- Redundancy
2
Q
What components power the AC system?
ASM 6.1.1
A
- 2 Integrated Drive Generators (IDG) (40 KVA)
- Auxiliary Power Unit (APU)
- Inverter
- Ram Air Turbine (RAT) (15 KVA)
- AC GPU receptacle
3
Q
What components power the DC system?
ASM 6.1.1
A
- 2 NiCad batteries
- 3 transformer rectifier units (TRU)
- DC GPU receptacle
4
Q
List all the DC buses
ASM 6.8.2.4
A
- GND service bus
- APU start bus
- 2 HOT BAT buses
- 2 DC buses
- 3 DC ESS buses
5
Q
What is the source priority order for powering the AC main buses?
ASM 6.8.3
A
- Onside
- Inside (APU GEN)
- Outside (GPU if connected)
- Cross-side (Opposite IDG)
6
Q
How does the IDG maintain a stable power output?
A
A constant speed drive (CSD) attaches the IDG to the AGB (accessory gear box)
7
Q
What monitors and controls the IDGs?
ASM 6.3.2.1
A
Each has a generator control unit (GCU)
8
Q
If only 1 IDG is on, what powers the other side? What if you start the APU? What would power it?
A
- IDG will power both sides through BTC 1
- APU will power the right side (system 2) through BTC 2
9
Q
Are the IDG icons on the MFD always in view even when the IDGs are not powered?
A
Almost always. They become 3 dashes if invalid or out of range. Otherwise they are always in view.
10
Q
Can one IDG power the entire electrical system?
A
Yes
11
Q
Does the IDG have its own oil supply? If yes, can you see it’s quantity?
A
Yes, No
12
Q
On the electric control panel, the amber lights near the IDG control knob indicates what?
A
Which IDG must be disconnected and its associated EICAS message
13
Q
What are three reasons for the IDG disconnect light to illuminate?
A
- High oil temperature
- Low oil pressure
- Annunciator test button
14
Q
If an IDG is mechanically disconnected can it be reconnected on the ground or in flight by the flight crew?
A
No, this is a maintenance function.
15
Q
What indication would you get with an IDG low oil pressure or high oil temperature?
A
An amber LED next to the associated IDG switch and an associated EICAS IDG 1(2) oil illumination
16
Q
During “normal operation” will a failed IDG de-power the respective AC bus?
A
No
17
Q
What happens when the IDG selector knob is in AUTO, OFF or DISC?
A
AUTO: Allows the automatic operation of the electrical system. It closes the IDG contractor, connecting the IDG to its respective AC bus.
OFF: The generator is de-engergized and the IDG contractor is opened isolating the IDG from the respective AC bus
DISC: must be held in this position for one second to mechanically disconnect the IDG
18
Q
What is the primary purpose of the AC generators?
A
To power the AC BUSs and the AC ESS BUS which…
Power the 3 transformer rectifier units TRU 1, 2 and ESS
19
Q
What is primary and alternate sources of power for the AC ESS BUS?
A
Primary is the AC BUS 2. ALT is AC BUS 1 (and the RAT when both AC BUSs 1 and 2 are not powered)
20
Q
What is the normal and alternate source of power for the AC standby bus?
A
Normal is the AC ESS BUS and the alternate is the AC inverter
21
Q
State the source priairoty for powering the AC main buses
A
Respective IDG
22
Q
Which AC source has priority, the APU or GPU
A
APUhas priority and will automatically switch when the API is ip and running
23
Q
Will the AC APU icon always be in view on the MFD>
A
No, only when the APU is available (3 seconds after 95%)
24
Q
What is the purpose of the transformer rectifier units?
A
To convert 115 VAX to 28 VDC
25
What happens when the TRU 1 (2) and TRU ESS switches are in AUTO?
AUTO allows automatic operation of the electrical system. TRU 1 and 2 connect to its respective DC BUS, TRU ESS connects to the ESS BUS 3
26
What does the OFF position of TRU 1 and 2 do?
Isolates the TRU from its respective DC BUS
27
What does the OFF position of TRU ESS do?
Isolates the TRU from ESS BUS 3
28
During normal operations, TRU 1 supplies power to what?
DC BUS 1, DC ESS BUS 1, DC ground service bus, HOT BATT 1, and BATT 1 charging
29
During normal operations TRU 2 supplies power to what?
DC BUS 2, DC ESS BUS 2, HOT BATT BUS 2, and BATT 2 charging
30
During normal operations TRU ESS supplies power to what?
DC ESS BUS 3
31
When are batteries being charged?
Whenever the TRUs are powered from any source
32
TRU transforms AC to DC, is there a way to change DC to AC?
Yes, the inverter
33
BATT 1 or 2 normally charges through which TRU?
the associated side
34
Cant eh APU fully replace a failed IDG?
Yes
35
The APU GEN button, when depressed, does what?
- Connects the APU GEN to the AC bus tie according to source priority and provided the power is within limits
- Allows automatic operation of the electrical system
36
What happens when he APU GEN pushbutton is out?
- Opens the APU GEN cofactor and isolates the APU from the AC BUS TIE. The APU GEN is tripped off line and de-excited
- White stripe illuminates
37
During ground operations with the APU operating, the failure of an IDG will cause its respective AC BUS to get power from where?
APU GEN
38
You receive the aircraft at the gate and it is powered by the AC GPU. You start the APU. Once it's up and running how can you tell the APU GEN has automatically taken over the electrical load?
AVAIL light on the AC GPU button and the MFD electrical page shows green APU icon
39
In flight, with the APU operating, an intentionally disconnected IDG will cause the respective AC BUS to seek power from?
APU GEN
40
What happens when the GPU pushbutton is out?
Isolates the AC GPU from the AC BUS TIE
41
At the gate, ground power is connected. What do you have to have to get an AVAIL light outside and in the cockpit?
Volts/Amps/Freqs are within limits
42
How is it known that an AC GPU is plugged in and the outside GPU panel button displays IN USE?
- GPU buttons display AVAIL and the GPU icon is presented on the electrical synoptic page
- Once the GPU button is pushed in, the button will display IN USE. Connects the AC GPU to the AC BUS TIE according to source priority
43
What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?
- Ground service bus is in use
| - Cockpit GPU button will display AVAIL even though the ground service bus is in use
44
Will the AC GPU icon always be in view on the MFD?
No. It comes into when when connected and the power is good
45
If the airplane is using the AC GPU and the APU is started what should the pilot be sure to do?
Deselect the AC GPU button so the power can be connected the next time it is used. Going from out to in closes the generator relay
46
Will the AC GPU provide power to start the APU?
No, the AC GPU will only charge the batteries
47
What will charge the batteries?
Any AC power source
48
The battery icon is always displayed on the MFD. How can you tell if the voltage is good?
- The parameters are indicated (voltage and temp). All the battery icon is green above 18 volts and white below 18 volts
- RJET limits: 22.5V for start and -20C
49
What does it mean when the battery associated digits turn RED on the MFD?
The battery temp reached 70C for 2 seconds. The BATT 1(2) OVERTEMP EICAS massage is also displayed.
50
Why is there an AUTO position on BATT 2?
BATT 2 supplies the APU START BUS during APU starting
51
Name a six items on the HOT BATT BUSES
- Engine Fire Extinguishers
- Fuel shutoff valves
- Hydraulic shutoff valves
- Engine oil level systems
- Refueling panel
- Water and waste system
52
What happens when BATT 2 switch is in AUTO or OFF?
AUTO: Allows automatic operation of the electrical system. BATT 2 connects to DC ESS BUS 2
OFF: The battery supplies power to the HOT BATT BUS 2
53
What happens with the BATT 1 selector ON or OFF?
ON: The battery is connected to the DC ESS BUS 1
OFF: The battery supplies power to the HOT BATT BUS
54
During an electrical emergency, the batteries supply essential loads for how long?
10 mins
55
How long will the aircraft batteries last without recharging?
10 mins
56
During an electrical emergency what equipment is available?
DU 2 (Locked into a PFD), DU 3, Clock, IESS, MCDU 2, CCD 1
57
Does turning the battery selector knobs to "ON/AUTO" cause the battery to power its respective HOT BATT BUS?
No
58
What is the min battery voltage for the SAFETY and POWER ON checklist?
22.5 VDC (needed for APU start)
59
What if the batteries are not at 22.5 VDC during the SAFETY and POWER ON checklist?
GPU can provide power to the aircraft. Reference SOP chapter 6 to determine how long is necessary to recharge the batteries
60
What is the min battery voltage to close the battery bus ties?
18 V
61
What battery is used for APU start?
BATT 2 powers the APU START BUS
| BATT 1 powers the APU FADEC (logic for the start)
62
Why is there an AUTO position for BATT 2?
- BATT 2 supplies the APU start bus to be powered exclusively during the APU start
- The disconnect of DC BUS 2
63
What is the min battery temp for APU start?
-20C
64
What would you do if the BATT 2 was colder than -20C
Connect the DC GPU which powers the APU start bus and isolates BATT 2
65
What is the purpose of the DC GPU receptacle
- For APU start when the batteries
66
What is the purpose of the inverter?
Converts 28 VDC from the batteries to 115 VAC to power the AC STANDBY BUS when an AC source isn't available
67
What happens when the AC BUS TIE switch is in AUTO?
Auto allows automatic operation of the electrical system. Controls the operation of the bus tie contractors IAW system logic
68
What does the OPEN 1 position of the AC BUS TIES knob do?
Opens the BTC 1 which segregates AC BUS 1 from 2
69
What does the OPEN 2 position of the AC BUS TIES knob do?
Opens the BTC 2 which segregates AC BUS 2 from 1
70
What happens if a power generating source fails?
Bus ties automatically connect to provide no system degradation
71
What happens when the DC BUS TIES switch is in AUTO or OFF?
AUTO: allows automatic operation of the electrical system
OFF: Opens all BUS TIE contactors
72
What is on the AC STANDBY BUS?
Engine exciters 1A and 2A
73
What powers the Ram Air Turbine (RAT)?
Airflow turns the RAT propeller which spins the turbine inside
74
When will the RAT deploy?
- Automatically deploys if AC BUS 1 and 2 are not powered
| - Manually by pilot
75
Both IDGs and the APU generator are rated at 40KVA. What is the RAT rated at KVA and volts?
15 KVA and 115 VAC
76
Is there an altitude restriction for operation of the RAT?
No
77
How long after deployment before the RAT will supply power?
8 secs
78
Is there a total loss of power during the 8 second RAT deployment?
No. HOT BATT BUS 1 and 2 supply power to DC ESS BUSS 1/2 and AC STANDBY BUS through the AC inverter
79
What BUSES does the RAT power?
AC ESS BUS, AC STBY BUS, TRU ESS, ESS BUS 3, DC ESS BUS 1, HOT BATT BUS 1, DC ESS BUS 2, HOT BATT BUS 2
80
With both IDGs and APU generator offline, and the AC BUS TIE set to AUTO, will the RAT power the AC BUSES via the AC ESS BUS?
No
81
What does the RAT power?
Powers the AC and DC ESS BUSES
82
What is the minimum airspeed for the RAT?
- 130 knots
- Below this speed power the to the DC ESS BUSES are initially powered by the battery, then load shedding occurs and eventually the AC ESS BUS is no longer powered
- 150 knots on the QRH checklist is to ensure that the ESS TRU contractor will close, Once it closes and the RAT is supplying the ESS BUSES it is possible to maintain the 130 knot minimum,
83
How would you deploy the RAT in the event of an automatic deployment failure?
Use the RAT manual deployment handle
84
If a TRU fails, will the respective DC BUS be unpowered?
No
85
Briefly describe the electrical power distribution and control system?
- 4 ICCs
| - 2 secondary power distribution assemblies (SPDAs)
86
What is an ICC?
An electrical control device which provides power distribution and protection for electrical loads
87
Name the four ICCs.
LICC, RICC, EICC, AICC
88
The ICCs are located where?
In the E-bays
89
What do the ICCs contain?
Line replaceable units and modules, thermal circuit breakers and the AC/DC buses including the essential buses and HOT BATT buses
90
Which ICC houses the the HOT BATT 2 and the APU start bus?
The AICC
91
What is an SPDA?
An electrical load-management unit powered by the ICC's that distributes electrical loads to aircraft systems IAW distribution logic
92
Each SPDA has specific slots that house what?
Electronic modules that provide associated functions such as COMM, data processing and power distribution. The MAU does the thinking, the ICC's provide the power and the SPDA's do the switching.
93
Four independent DC BUSES power each SPDA. Which buses power SPDA 1?
DC BUS 1, DC ESS BUS 1, DC ESS BUS 2, and DC GND SVC BUS
94
Four independent DC BUSES power each SPDA. Which buses power SPDA 2?
DC BUS 2, DC ESS BUS 1, DC ESS BUS 2, and DC GND SVC BUS
95
What type of CB protection is incorporated into the SPDAs?
Electronic CBs (solid state CBs)
96
Can the remote electronic CBs be monitored? (in the E-Bays?)
Yes via the MCDU
97
What items will the SPDA command to be load-shed IOT prevent the remaining electrical source from overloading?
- Right windshield
| - Galleys
98
Can the flight crew reset the ICC and SPDA remote electronic CBs?
- ICC CB's can only be reset by maintenance on the ground
| - SPDA CB's can be reset bia the MCDU
99
What powers the IESS in case of electrical emergency?
RAT/batteries
100
If the APU is available and one engine generator fails, the failed generator is replaced by:
APU GEN
101
If you start an engine at the gate with the GPU, is the electrical system split?
Yes
102
During dual engine failure checklist says min airspeed of 265 knots. Why?
Windmill speed for the start envelope. If you start the engine with insufficient airflow you risk core lock
103
You board a depowered airplane and proceed to establish electrical power. Which panel is of relevance to you and where is it?
- Galley electronic panel behind cockpit door
| - Ground service buses must be disconnected prior to applying power through the AC GPU
104
What happens if only the ground personnel push their GPU button?
Their button shows IN USE and the cockpit shows AVAIL. Only the ground service buses are powered
105
How many display units (DUs) come to life when you bring the batteries online? Which ones are they?
2, DU 2 and 3
106
An electrical PBIT test during the power-up of the aircraft will not be interrupted if?
APU is started
107
The STBY AC BUS is normally powered by the ESS AC BUS. It will be powered by the inverter when the aircraft is powered by what?
Batteries only
