Q400 > Electrical > Flashcards

Electrical Flashcards

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1
Q

EPGDS?

A

Electrical power generation and distribution system

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2
Q

What makes up the DC system?

A

3 batteries
2 Engine driven starter generators
2 TRUs
1 APU
DC external power

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3
Q

What are the batteries?

A

3 Nickel Cadium (Nicad) batteries
40 amp hour
24 volts DC

Main, Aux, Standby

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4
Q

What are the generators rated too?

A

400 Amps max

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5
Q

How many volts are the generators?

A

28.5 V DC

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6
Q

What are the TRUs max amp?

A

300
28 V DC

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7
Q

What is the APU max amps?

A

400

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8
Q

AC electrical system includes?

A

2 engine driven generators mounted in the prop reduction gearbox
AC external power receptacle

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9
Q

What do the AC gen’s produce?

A

115 V threes phase variable frequency AC power

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10
Q

EPCU?

A

Electrical power control unit reconfigures the system if there is a power source failure or bus fault

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11
Q

Can the AC gens power the whole electrical system

A

Yes

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12
Q

Where are the main and aux batteries?

A

Aircraft nose compartment left side

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13
Q

Are the main and aux battery used to assist engine starting even when external DC power is connected?

A

Yes

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14
Q

Where is the standby battery?

A

Left nose compartment upper (in the compartment above the other two batteries)

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15
Q

Can the standby battery power the L DC MAIN BUS?

A

No one way power so it only gets charged

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16
Q

Purpose of standby battery? (2 things)

A

Supply power to essential bus during an electrical emergency mode.
It also provides protection by absorbing voltage and current spikes

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17
Q

How long Backup electrical power in flight provided by the batteries?

A

Approx 60mins

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18
Q

What is the hot battery bus powered by?

A

Standby battery

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19
Q

Battery Bus powers?

A

• CLOCKS ONE & TWO
• BATTERY MASTER SWITCH
• BATTERY POWER FOR REFUELING
• FIRE BOTTLES DISCHARGE SQUIBS
• FUEL & HYDRAULICS SHUTOFF VALVES
• ENGINE FUEL METERING UNITS
• CARGO COMPARTMENTS FIRE SYSTEMS
• APU FIRE BOTTLE SQUIB-MANUAL DISCHARGE
• FLIGHT DECK DOME LIGHTS & BOARDING LIGHTS
• EMERGENCY POWER-PASSENGER ADDRESS SYSTEM

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20
Q

Switched battery power bus is powered by?

A

Either main batt, aux batt or left ess bus

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21
Q

What does the switched battery power bus supply power to?

A

Electronic integrated standby instrument (EISI)
#1 VHF receiver and standby control head
Storm lights and CCT breaker lights
Back lighting for compass

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22
Q

Turning battery master on does what?

A

Connects the 3 batteries to the essential buses

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23
Q

What batteries connect to the R ess bus?

A

Main and standby

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24
Q

What does the aux battery connect to?

A

Left essential bus which also powers the switched battery bus

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25
The EPCU is powered by?
Essential buses
26
MAIN BATT switch on does?
Ties the main battery to the Right Main DC Bus and the switch batter power bus. Two way flow from main battery to right main dc bus
27
AUX BATT switch on?
Connects aux batt to Left Main DC bus and switch batter power bus. Two way power flow between aux bat and left main dc bus
28
STBY BATT on?
Connects standby batt to the Left Main DC Bus. One way only to change to standby battery
29
If there is a bus fault or during emergency electrical ops what prevents the batteries being connected to the Main DC buses?
EPCU logic
30
Battery caution lights illuminated when?
When the battery are switched off or if there is an electrical fault and it has been automatically disconnect from its respective bus
31
How to monitor battery loads?
Electrical systems pages on either MFD (ENG SYS button)
32
What lights will you get if there is a batter overheat?
Warning light STBY BAT HOT AUX BAT HOT MAIN BAT HOT
33
Battery overheat temp?
>71 degrees = warning lights <63 degrees = warning lights extinguish
34
What are the 6 DC buses that are powered by external DC power on the ground?
2 Ess buses 2 main buses 2 secondary buses
35
If the ground power malfunctions (over or under voltage) what happens?
> 31 volts or <22 volts. The EPCU auto disconnects the external power source. After the malfunction is rectified then the DC external power switch need to be cycled which will also reset the EPCU protection logic
36
What do the Gen 1 and Gen 2 switches do?
Control the engine driven DC started generators
37
What position are Main to secondary bus ties prior to AC generators online?
They are closed to allow the secondary buses to be powered because the ac gens come online
38
Secondary buses powered by?
AC generators through the TRUs. To get the AC gens online the condition levers must be forward of 850 RPM
39
DC start Gen mounted?
Right side of the engines accessory gearbox and are air cooled
40
Generator control unit (GCU) does what during the start?
NH >50% the GCU converts the starter generator from starter mode to generator mode
41
GCU does what after start?
The GCU ensures generator supplies 28.5 volts DC and 400 amperes to it’s associated MAIN DC BUS
42
What is the DC Gen load showing on the electrical page?
+1.00 means 100 % load on the generator.
43
DC GEN caution light
Generator offline or Gen off
44
DC GEN HOT caution light
Starter-Gen overheat. EPCU does not automatically remove the generator in this situation it must be turned off
45
APU provides (volts)? And max load output?
28V AC 400 Amps
46
TRUs do what?
Change 115V variable freq AC to 28V DC 300 amp
47
TRU supply power to which buses?
Secondary buses when AC Generator or external AC power is available
48
If both DC starter gens fail can the TRUs power all the DC system?
Yes
49
If the TRU is offline or has failed what caution light will you see?
L or R TRU
50
If the TRU is too hot what will you see?
L OR R TRU HOT. It will extinguish once temp decreases
51
EPCU does what?
Monitors and protects by controlling 4 bus ties. Which can tie buses together when a DC generation source fails. Main bus tie 2 Main to sec Secondary bus tie
52
If the Main Bus Tie switch is not tied but there is an DC Gen failure will the main bus tie close automatically?
Yes the EPCU will close it regardless of what the switch is doing
53
If a TRU fails what bus tie will EPCU close?
Secondary bus tie
54
If both DC Gens fail which bus ties will close for all buses to remain powered?
Secondary to main bus ties (vertical bus ties)
55
Both TRUS failed what bus ties close?
Secondary to main
56
Both TRU and single DC Gen all failed what happens?
EPCU auto load shed. Only main bus tie closed so only main buses are powered. Results in no secondary bus
57
What is Emergency Mode of Operation? (How many sources of power are available)
EPCUs emergency mode occurs when airborne, DC gens not available and at least one TRU is not available
58
EPCU emergency mode what happens?
Auto disconnect the main buses from the batteries. Essential buses remain powered from the batteries Secondary buses remain powered from remaining TRU This is load shedding and loss of services from both main buses
59
DC BUS caution light
Bus fault and the bus has been isolated by the EPCU and DC GCU protection EPCU prevents the main and main to secondary bus tie from closing to isolate the bus
60
DC BUS fault reset switch used when?
As per QRH when it is a stand alone caution light probably the result of a spurious electrical malfunction
61
L Main Bus Fault - what caution lights illuminated?
DC BUS STBY BATTERY AUX BATTERY #1 DC GEN
62
R Main Bus Fault - what caution lights illuminated?
DC BUS MAIN BATTERY #2 DC GEN
63
Secondary Bus Fault what CCT breaker will trip?
L or R TRU
64
Can AC external power be used for engine starts?
No the TRUs have a 300amp limit and could be damaged
65
AC gens supply what power and where are they mounted?
115V three phase variable frequency Propeller reduction gearbox
66
How are the AC gens cooled?
Oil cooled
67
What systems use 115V variable AC power?
De ice and anti ice heaters STBY hyd pump 2 TRUs # 1 and 2 Aux fuel pumps
68
What caution light do you get if there is a failure of an AC Gen?
#1 or # 2 AC GEN Cross tie automatically happens to enable both left and right variable AC buses to be powered
69
If a GCU detects a bus fault what will it do?
Isolate the bus. Meaning all services from effected bus are lost
70
Gen overheat caution light?
#1 or #2 AC GEN HOT Must be turned off
71
Can 1 AC Gen power the entire electrical system both AC and DC?
Yes!!
72
During flight if both TRUs and a #1DC generator fail?
The secondary buses are shed
73
Tripping of the L TRU circuit breaker may be an indication of
A left secondary bus fault
74
Which of the following systems is NOT powered by the AC electrical system?
Cockpit display units
75
Each engine driven start generator is rated at?
400amps
76
The hot battery bus is powered by the
STBY battery
77
The receptacle for external AC power is located?
On the inboard side of the #2 nacelle
78
Battery hot warnings will occur when the battery temperature exceeds?
71 degrees
79
During normal operations in flight the right secondary bus is normally powered by the
Right TRU
80
The BUS FAULT RESET switch on the overhead panel may be used in response to a
DC BUS caution light
81
The maximum battery load meter reading for takeoff is?
0.10
82
During flight if both TRUs fail which bus ties will be closed?
Both secondary to main bus ties
83
Illumination of the L TRU caution light indicates?
The TRU is not energised
84
If there is an over voltage supplied by external DC power?
The EPCU automatically disconnects external power
85
The APU starts generator is connected to the
Right main bus
86
The DC generators are mounted to
The engine accessory gearbox
87
Illumination of the DC BUS caution light indicates?
A DC bus fault has occurred
88
The #1 engine starter generator is connected to the
Left main bus
89
Selecting the MAIN BATT switch on directly connects the battery to the
Right main bus
90
Illumination of the MAIN BATT HOT warning light indicates?
An overheat condition has been detected
91
Illumination of the #2 AC GEN HOT caution light indicates an over temperature condition
The generator must be taken offline by the crew
92
In flight how many sources of generated DC power are required to power all DC buses
Two
93
Illumination of the MAIN BATTERY caution light indicates
The battery is not connected to the right main bus
94
AC generators come online at approximately what propeller RPM
400NP
95
The DC starter generators are cooled by
Ram Air
96
Selecting the MAIN BATT switch in connects the battery to the
Right main bus
97
Where there is a bus fault or power source failure the DC electrical system is
EPCU
98
TRUs location ?
Aircraft nose compartment Access from the upper right access door.
99
During the emergency mode, the MAIN and AUXILIARY BATTERIES are automatically reconnected to the MAIN BUSES should you attempt?
an airborne engine start. The connection of the batteries to the buses occurs even if the respective individual MAIN BATT and AUX BATT switches are in the OFF positions.
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