Electrical Flashcards
(128 cards)
1
Q
What is an IDG? How many are on the E175?
A
Integrated Drive Generator, 2
2
Q
What is the IDG output?
A
115VAC, 400Hz, 40KVA
3
Q
What is the APU output?
A
115VAC, 400Hz, 40KVA
4
Q
What does the GPU stand for? What is the GPU output?
A
Ground Power Unit, 115VAC, 400Hz, 40KVA
5
Q
What is the RAT? What is the RAT output?
A
Ram Air Turbine, 115VAC, 400Hz, 15KVA
6
Q
How many inverters are on the E175? How many VAC is the inverter?
A
1, 250VAC
7
Q
What is the purpose of an inverter?
A
Converts VDC to VAC
8
Q
When can the IDG power both AC buses?
A
On the ground and in flight
9
Q
When can the APU power both AC buses?
A
On the ground and in flight up to FL330
10
Q
Can the GPU power both AC buses?
A
Yes
11
Q
What is the primary source of AC power?
A
IDGs
12
Q
What happens when the IDG knob is in the AUTO position?
A
system logic controls contactor
13
Q
What happens when the IDG selector knob is turned OFF?
A
opens contactor to break the circuit disconnecting the IDG from the electrical network
14
Q
What happens when the IDG DISC position is selected?
A
This position mechanically disconnects the CSD (Constant Speed Drive) from the IDG
15
Q
Can the flight crew reconnect the IDG after IDG DISC?
A
No, only maintenance can reconnect the IDG
16
Q
Amber light accompanied by the EICAS oil message indicates
A
IDG disconnect is required due to High Oil Temperature or Low Oil Pressure
17
Q
What are the secondary sources of AC power?
A
The APU, the GPU
18
Q
What power source is required to start the APU?
A
DC Power is required
Either BATT 1 and BATT 2 or BATT 1 and DC GPU are required for APU start
19
Q
What is the function of BATT 1 and BATT 2 for APU start?
A
BATT 1 controls the APU’s FADEC; BATT 2 is isolated from the network to exclusively power the APU START BUS
20
Q
What is the minimum VDC for APU start?
A
22 VDC minimum must be noted during the Safety and Power On Checklist to consider APU start
21
Q
What is the minimum VDC required to close the battery contactor during APU start?
A
18 VDC minimum required to close the battery contactor (connect the APU to the electrical network)
22
Q
What is the minimum BATT 2 temperature required for APU start?
A
-20 degrees Celsius
23
Q
What 3 methods/locations that can be used to turn on the GPU?
A
- AC GPU panel (powers AC&DC ground service buses and TRU1)
- Opposite the FWD lav (powers AC&DC ground service buses and TRU1)
- Cockpit overhead panel (powers whole aircraft network)
24
Q
What are the messages/annunciations you will see if the parking brake is released with the GPU connected?
A
CAS message: GPU CONNECTED; Master Caution and aural warning
25
What CAS message will you see if the GPU is connected and power meets system requirements?
AVAIL
26
What CAS message will you see if the GPU is running and is the priority (powering the AC system)?
IN USE
27
What is the normal AC electrical priority?
1. Onside (IDG)
2. Inside (APU)
3. Outside (GPU)
4. Cross-Side (Other IDG)
28
What does the inverter power?
The inverter powers the AC STANDBY BUS when the normal AC power source is not available so that “A” igniters always have a source of power
29
What is the purpose of the RAT?
Emergency AC power source
30
Are there any altitude or airspeed restrictions for RAT deployment?
No
31
When does the RAT deploy and what does the RAT power?
The RAT automatically deploys if both AC buses lose power during flight (electrical emergency) to supply the ESS buses
32
Can the RAT be deployed manually?
Yes via the RAT Manual Deploy Lever
33
During RAT deployment, what source provides aircraft power?
The batteries provide power for approximately 8 seconds
34
What minimum airspeed is required for RAT operation?
130kts
35
What happens if the aircraft speed is below the minimum required (130kts) while the RAT is deployed?
The RAT will only provide power to the AC ESS bus; the BATTS will provide power to DC ESS bus and AC STANDBY bus; As airspeed decreases, load shedding occurs until AC ESS bus is no-longer powered
36
What sources provide the aircraft’s DC power?
3 TRUs, 2 Batteries, 1 DC GPU
37
What is a TRU?
Transformer Rectifier Unit, Converts AC to DC and can change the voltage
38
What is the output of the TRUs?
28 VDC, 300 A
39
What is the output of the batteries?
24 VDC, 27 AH
40
What is the output of the DC GPU?
28 VDC
41
What is the primary source of DC power?
TRUs
42
The TRUs convert ___ to ___
115 VAC to 28 VDC
43
Do the TRUs work together?
No, the TRUs work in isolation from each other
44
What is the secondary source of DC power?
The batteries
45
What type of batteries do we have?
NiCad (Nickel-Cadmium as electrodes)
46
How are the batteries charged?
Via any power source through the TRUs
47
What is the volt minimum to close the battery contactor?
18 Volts
48
How long will the batteries provide power during an electrical emergency?
10 minutes
49
What does the DC GPU connect to?
the APU start bus and replaces BATT 2 during APU start
50
How can the DC GPU be turned on?
By the button on the ramp
51
Can the DC GPU charge BATT 2?
No
52
What is SPDA an abbreviation for?
Secondary Power Distribution Assemblies
53
What is the purpose of the SPDAs?
manage electrical load, distribute power according to system logic, performs BITs on many items
54
What powers the SPDAs?
SPDAs receive power from the ICCs
55
In general, how to the ICCs and SPDAs work together?
The ICCs collect and confirm the power is safe and then sends it to the SPDAs, which distributes it
56
What is a hot bus?
A hot bus is a bus that is still powered ON when everything else is off - what is still powered ON when you get to the airplane in the morning cold and dark
57
What 8 items are powered by the DC HOT BUS 1?
Battery 1
FWD Service/Courtesy Lights
DC Ceiling Lights
Engine 1 Oil Level Indication
Engine 1 Fuel SOV
Engine 1 HYD SYS 1 SOV
Fire Bottle 1A (Handle 1, Bottle A)
Fire Bottle 2A (Handle 2, Bottle A)
58
What 9 items are powered by the DC HOT BUS 2?
Battery 2
CMC Central Maintenance Computer
Refuel/Defuel Panel
Engine 2 Oil Level Indication
Engine 2 Fuel SOV
Engine 2 HYD SYS 1 SOV
Fire Bottle 1B (Handle 1, Bottle B)
Fire Bottle 2B (Handle 2, Bottle B)
Water and Waste System Controller
59
How many networks make up the electrical system on the airplane? Why?
2 Independent Networks; Redundancy and Fault Isolation
60
What happens if a power generating source fails?
Bus ties automatically connect to provide no system degradation
61
What components power the AC system?
2 IDGs, APU, Inverter, RAT, AC GPU receptacle
62
What components power the DC system?
2 NiCad batteries, 3 TRUs, DC GPU receptacle
63
How does the IDG maintain a stable power output?
A CSD Constant Speed Drive attaches the IDG to the AGB Accessory Gear Box
64
What monitors and controls the IDGs?
Each has a GCU Generator Control Unit
65
Can 1 IDG power the entire electrical system?
Yes
66
What will cause the amber IDG light on the overhead panel to illuminate?
High oil temperature, low oil pressure
67
If an IDG is manually disconnected can it be reconnected by the flight crew?
No, only maintenance can reset the IDG
68
What is the primary purpose of the AC generators?
1. To power the AC BUSES and AC ESS BUS which… 2. Power the 3 TRUs 1, 2, and ESS
69
Can the APU replace a failed IDG?
Yes
70
How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?
GPU button displays 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 provided another AC power source is available
71
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
72
If the airplane is using the AC GPU and the APU is started what should the pilot be sure to do?
Deselect the GPU button before the next GPU connection
73
What is the purpose of the DC GPU receptacle?
For APU start when batteries < 22 VDC; or If battery temp is < -20 degrees C
74
What is the minimum battery temperature for APU start?
-20 degrees C
75
What is the minimum battery voltage to close the battery bus-tie?
18 votls
76
What battery is used for the APU start?
BATT 1 powers the FADEC and EICAS for monitoring; BATT 2 powers the APU Start Bus
77
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 is not available
78
What is on the AC STANDBY BUS?
Engine exciters 1A and 2A
79
What powers the RAT?
Airflow turns the RAT propeller which spins the turbine inside
80
When will the RAT deploy?
Automatically deploys if AC BUSES are not powered; Manually by pilot
81
How long after deployment before the RAT will provide power?
8 seconds
82
Is there a total loss of power during the 8 second RAT deployment?
No. Batteries supply power to the DC ESS BUSES and AC STANDBY BUS
83
What does the RAT power?
AC ESS BUS
AC STBY BUS
DC ESS BUSES 1,2,3
HOT BATT BUSES 1,2
Batteries
84
What is the minimum airspeed for the RAT?
130 KIAS; Load shedding occurs below this speed
85
When is the RAT icon displayed on the electrical synoptic page?
When the RAT is deployed
86
What manages the electrical system?
4 ICCs, 2 SPDAs
87
What is an ICC?
An electrical control device, which provides power distribution and protection for electrical loads
88
What is an SPDA?
An electrical load-management unit (powered by the ICCs), that distributes electrical loads to aircraft systems according to distribution logic and performs BITs on many components
89
Can the flight crew reset the ICC and SPDA remote electronic CBs?
ICC CBs can only be reset by maintenance; SPDA CBs can be reset via the MCDU
90
What is a MAU or modular avionics unit?
Cabinet of avionics components and some non-avionics components. MAU 1 and 2 are in the FWD Ebay. MAU 3 is in the mid ebay
91
What does the AVAIL lamp on the overhead panel mean?
The external power is connected and all quality requirements are satisfied.
92
If the APU is available and one engine generator fails, the failed generator is replaced by?
The APU generator
93
Can you reconnect the IDG in flight?
No
94
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 batteries only
95
What converts DC to AC?
The inverter
96
What does IDG stand for?
Integrated Drive Generator, attached to the AGB
97
What is difference between the electrical power created by the engines v the APU?
The engines have a CSD Constant Speed Drive that converts variable engine speed into constant generator speed
98
How is the IDG oil system cooled?
Air Cooled
99
What controls the IDGs?
The GCUs Generator Control Units
100
What could happen if the IDG disc light illumiunates but you don’t disc the IDG?
The IDG features an input shaft shear section and a thermal disconnect operation that will permanently disconnect the IDG if there is no manual disconnection.
101
How does the RAT maintain a constant electrical output?
The RAT blades are variable-pitch type
102
How will you know if the RAT failed to deploy and must be deployed using the RAT manual deploy lever?
The BATT DISCHARGING EICAS message appears.
103
What is the purpose of the inverter?
To provide backup electrical power while the aircraft is only powered by the batteries (during RAT deployment).
104
What is the only item on the aircraft to provide single phase power?
The inverter converts 28VDC to 115VAC, 400Hz, single-phase
105
What are the 4 ICCs?
The Left Integrated Control Center LICC, Right Integrated Control Center RICC, Emergency Integrated Control Center EICC, and Auxillary Integrated Control Center AICC (for APU start)
106
What is the secondary DC power source?
2 Nickel-Cadmium Batteries
107
Where are batteries 1 and 2 located?
BATT 1 in the Fwd E-bay, BATT 2 in the aft E-Bay
108
What charges the batteries normally?
Any AC power source, Even the RAT
109
With BATT 1 OFF, or BATT 2 OFF, will the batteries be connected to anything?
Yes, the HOT BATT Buses
110
What does an ICC provide? What is it physically?
Power distribution and protection. It is an electronic device.
111
Where are the respective ICCs located?
LICC and RICC in the middle e-bay, EICC in the fwd e-bay, and AICC in the aft E-bay (for APU start)
112
What are the components of the ICC electrical device?
AC/DC buses
Thermal Circuit Breakers (remote via the MCDU)
LRUs Line Replaceable Units
LICC: AC Bus 1, DC Bus 1, AC/DC Ground Service Buses, LRUs: TRU 1, GCU 1, External Power Modules, Several Thermal CBs
RICC: AC Bus 2, DC Bus 2, DC ESS Bus 2, LRUs: TRU 2, GCU2, ACGU (Aux GCU), several thermal CBs
The DC ESS Bus 2 is here instead of the EICC in case of damage to the fwd e-bay
EICC: AC ESS Bus, DC ESS 1/3, Standby AC Bus, HOT BATT Bus 1 ,LRUs: TRU ESS, several thermal CBs
AICC: APU start bus, HOT BATT BUS 2, several thermal CBs
113
How will you know if a remote CB trips in the ICC? Can they be reset in the air?
REMOTE CB TRIP EICAS Message
They cannot be reset in-flight
114
What is the SPDA purpose? What does SPDA stand for?
SECONDARY Power Distribution Assembly. Manages and distributes power from the ICCs based on the AUTO logic
115
Where are the SPDAs installed?
SPDA 1 in the fwd e-bay, SPDA 2 in the mid e-bay
116
Each SPDA has slots and electronic remote CBs, unlike the ICCs which are thermal CBs. If a SPDA CB trips, can it be reset?
Yes via the MCDU because it is electric, unlike the ICCs which are thermal and can only be reset on the ground. Vital system CBs are on the circuit breaker panel in the cockpit.
117
What normally powers the AC ESS bus?
IDG 2
118
What do TRUs do?
“Rectify” AC power to DC, and “transform” it down in voltage
119
Where are the GCUs located and what do they do?
They are Generator Control Units that control the IDGs. They are located in the RICC and LICC as LRUs. They send the signal to open or close the IDG line contactors, which are also located in the LICC and RICC.
120
Can DC ground power be used in lieu of AC ground power?
No. DC ground power (GPU) can only be used for APU start.
121
Can the AC or DC GPUs be powered on from outside the airplane?
Yes via the respective buttons which will power the ground service buses OR via the FA panel GND SVC button. NOTE: THE DC GPU can ONLY be powered on from outside the airplane via the button
122
BIT
Built-In Test
123
BTC
Bus Tie Contactor
124
GCU
Generator Control Unit
125
IDG
Integrated Drive Generator
126
MAU
Modular Avionics Unit
127
PBIT
Power Up Built-In Test
128
When will the BATT 1(2) OVERTEMP EICAS warning be triggered?
Whenever the battery temperature reaches 70°C for at least 2 seconds, the associated indication becomes red and the EICAS WARNING message BATT 1 (2) OVERTEMP is triggered.
