Electrical Flashcards

1
Q

What types of components generally use AC power?

A

Aircraft components incorporating some type of movement or motor function (e.g. motors, heaters, and chargers).

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2
Q

What types of components generally use DC power?

A

Normally used for control functions or steady-state operations.

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3
Q

How many TRU’s convert AC to DC power?

A

Five (5)

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4
Q

What’s the difference between red and black circuit breakers?

A

Red CB’s are related to essential circuits and black CB’s are considered non-essential

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5
Q

What’s the rating of the IDG’s?

A

They’re rated at 40 kVA and provide three-phase, 400 Hz, 115 VAC power

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6
Q

How can a GCU be reset?

A

By cycling associated generator control switch (L GEN, R GEN or APU GEN) to OFF and then ON. This action causes the
software to re-initialize.

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7
Q

Describe the APU generator.

A

It’s mounted on the APU, is usable on the ground, or in flight and produces 3-phase, 400 Hz, 115V AC power. It’s physically and distinctly different from IDG’s but produces the same type of power.

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8
Q

What’s the purpose of GCU’s?

A

They work with aircraft electrical system to provide quality power

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9
Q

True/False: All non-failure AC power transfers are NBPT’s, except between external AC power and APU power sources.

A

True

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10
Q

Would transfer of power between the APU generator and external AC power be a break or no-break power transfer?

A

APU generator and external AC power are not frequency controlled by GCU and BPCU; therefore, power transfer between these two sources are break power transfers and result in momentary power loss during transfer.

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11
Q

How is electrical power normally controlled?

A

By two (2) BPCU’s and three (3) GCU’s. BPCU’s are the brains of the system and control most of the contactors

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12
Q

What causes the “AC” legend of AC/DC RESET switchlight to activate?

A

Fault in Main AC or Emergency AC bus, a logic fault within BPCU, or by a relay or component failure

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13
Q

What happens when you depress the RESET switch?

A

It resets lockout and allows tripped contactors to close if the fault no longer exists

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14
Q

When would you select L/R Bus Tie to ISLN?

A

When directed by a checklist. It prevents the associated contactor from closing and isolates respective main AC bus from other power sources.

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15
Q

If both AC and DC external power is connected, which has priority?

A

External AC

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16
Q

Describe RAT deployment.

A

It’s totally manual and is accomplished by pulling the guarded RAT DEPLOY handle.

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17
Q

What’s the rating of the RAT?

A

15 kVA

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18
Q

What does the RAT power once it reaches operating speed (usually 5-8 seconds)?

A

FCC UPS bus and EBHA bus through Emerg AC bus, and both Essential DC buses through Left and Right ESS TRU’s

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19
Q

How is the RAT stowed?

A

On the ground using an installed hand-operated piston pump that is mounted above the RAT assembly: it cannot be restowed in flight.

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20
Q

What happens as the airspeed falls below the limit of RAT operation (180 knots)?

A

The RAT stops operating and Main, UPS and EBHA batteries begin to power flight critical systems for up to 16 minutes.

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21
Q

What’s the source of power for personal electronic devices, electric razors, hair dryers, blender, toaster, etc.?

A

50 or 60 Hz power system comprised of two converters. One converter is active while the other operates in standby. New architecture has converters operating in parallel for more power: if one fails, it reverts to single converter operation.

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22
Q

True/False: CABIN / GALLEY and 60 HZ Master switches are wired in series (i.e. both must be selected ON for converters to produce power).

A

True. CABIN / GALLEY Master switch also controls 28 VDC to cabin. It’s a single switch for load shedding all power to cabin.

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23
Q

When are the L and R AUX DC buses load shed?

A

During single generator operation, RAT generator operation, battery only operation, loss of one or both hydraulic systems, or when the Aux TRU is powering another DC bus. Load shed feature is inhibited on the ground.

24
Q

Describe the purpose of the fifth or Aux TRU.

A

It serves as a backup to the primary TRU’s. When not serving in a backup role, the Aux TRU powers the Left and Right Aux DC buses which provide 28VDC power to cabin loads.

25
Q

What causes the “DC” legend of AC/DC RESET switchlight to activate?

A

Fault in Main DC, Essential DC or Aux DC buses, a logic fault within BPCU, or by a relay or component failure

26
Q

When the L MAIN TRU switch is depressed, the switchlight indicates R AC. What does this mean?

A

It means the Left Main TRU is powered by the Right Main AC bus.

27
Q

Describe the main batteries.

A

Two main batteries are located in the tail compartment: they’re Ni-Cad (28V DC, 53 amp/hour).

28
Q

The batteries have three modes of operation. What are they?

A

Charge, discharge, and TR

29
Q

What are main battery charging requirements?

A

AC power applied, battery switches must be on and battery voltage must be greater than 7 volts

30
Q

When is the TR mode initiated?

A

If battery switches are selected ON, main AC buses are powered, and the following occur – APU start switch is selected ON, aux pump is turned on, or essential DC buses require power from batteries.

31
Q

What mode of the battery/chargers is lost with loss of Main AC buses?

A

TR and charge mode

32
Q

The batteries have a split bus configuration. What does that mean?

A

Only the left battery is involved in APU start. Both batteries power the aux pump.

33
Q

When should you remove the batteries?

A

Cold soak conditions (-20°C)

34
Q

When would the MAIN BATTERY switches indicate amber ON?

A

When starting APU (left battery discharge only), operating aux pump, or powering ESS DC buses if MAIN BATTERY switches are selected ON and ESS DC buses have no other source of power

35
Q

What additional function does the right battery have on the ground?

A

It’s used to power the ground service bus when not powered by the right main DC bus or external DC power

36
Q

What’s the minimum battery voltage required during the cockpit preflight Inspection?

A

22 volts

37
Q

What action should be taken if the voltage on either of the main batteries is < 22 volts?

A

Refer to the GVI (G650) Maintenance Manual

38
Q

On a dark airplane, what occurs when the EXTERNAL BATTERY switch is selected to ON?

A

Power is provided from both main aircraft batteries and the anti-collision beacon illuminate

39
Q

What’s the Aux TRU priority?

A

Essential before main and left before right

40
Q

What’s the function of the EBHA battery?

A

It provides power to MCE’s on Electric Backup Hydraulic Actuators (EBHA’s)

41
Q

What’s the purpose of the UPS battery?

A

It’s a dedicated source of power for FCC Channel 1A, FCC Channel 2B, BFCU, and EBHA remote electronics units (REU’s).

42
Q

Describe the emergency batteries.

A

There are two (2) 24V DC, 10.5 amp/hour lead acid emergency batteries on the aircraft: one located up forward in the LEER and one located back aft on the left side of the baggage compartment in the Auxiliary EER.

43
Q

What are the three modes of the emergency batteries?

A

Like the main batteries, they have three (3) modes of operation: charge, discharge, and TR mode.

44
Q

If all sources of power are lost, how many minutes will the emergency batteries provide electrical power to the left and right emergency DC buses, essential flight instrument bus,
and inertial reference units to support equipment essential for safety of flight as well as emergency lighting?

A

45 minutes

45
Q

How are the emergency batteries activated?

A

The ON switch is depressed or they’re ARMED and the left or right essential DC bus drops below 20 VDC (even momentarily)

46
Q

What items are powered down to emergency batteries?

A

Both SFD’s without air data
Both clocks
IRU’s
MCDU#1 displays STBY ENGINE page
MCDU#3 displays Backup radio tuning page
All three ACP’s

47
Q

What’s the purpose of the ground service bus (GSB)?

A

To provide DC power to equipment required for minimal servicing while on the ground

48
Q

What are the sources of power for the ground service bus?

A

Right main DC bus, external DC, or right battery

49
Q

Name the locations of the four (4) GSB control switches.

A

One behind the cockpit on the REER System/Monitor Test panel, one in the Security / Gnd Svc panel, one on the ground service panel in the tail compartment, and one in the refuel panel.

50
Q

What happens on a dark airplane when the GND SVC BUS switch on the Security / Gnd Svc panel is selected to ON?

A

The right battery powers the ground service bus and the anti-collision beacon illuminates. In addition, both SMC’s and MCDU #2 are powered.

51
Q

There are four (4) GND SVC Bus annunciator lights: one on the cockpit EPCP, one in the Security / Gnd Svc panel, one in the refuel panel, and one in the ground service panel in the tail compartment. When do they illuminate?

A

When the GND SVC BUS is being powered by the right battery or by external DC power (i.e. other than its normal source of power).

52
Q

When is the ground service bus automatically deactivated?

A

When all the doors are closed: tail compartment door, main door, Security / Gnd Svc panel door, and refuel door

53
Q

What’s the purpose of the secondary power distribution system (SPDS)?

A

It takes 28 VDC and 115 VAC power from the primary power system and distributes it to various aircraft loads

54
Q

The SPDS is composed of two Remote Interface Units (RIU’s) and eight (8) Modular Power Tiles (MPT’s) (4 for AC and 4 for DC). What’s the difference between RIU’s and MPT’s?

A

The RIU’s perform system control functions and interface with other aircraft systems: they’re the brains of this system.
The MPT’s perform power routing and circuit protection functions using AC and DC Solid State Power Controllers (SSPC’s).

55
Q

How many MCDU’s can be used to simultaneously control the SSPC’s?

A

Two: the third MCDU will indicate “SSPC SYSTEM BUSY, MAXIMUM OF TWO MCDU’S ALREADY CONNECTED.”