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Study Guide > Electrical > Flashcards

Electrical Flashcards

1
Q
  1. How is AC power normally produced?
A

By engine driven Integrated Drive Generators (IDGs) and/or APU generator.

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2
Q
  1. What’s the purpose of emergency batteries?
A

They power emergency avionics and emergency egress lighting.

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3
Q
  1. What’s the difference between red and black circuit breakers?
A

Red CBs are related to essential circuits and black CBs are considered non-essential.

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4
Q
  1. What’s the purpose of GCUs?
A

They work with electrical system to provide quality power.

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5
Q
  1. 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.

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6
Q

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

A

True

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7
Q
  1. How is electrical power normally controlled?
A

By two (2) BPCUs, three (3) GCUs and two (2) ESCs. BPCUs are brains of system and control most contactors.

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8
Q
  1. Describe emergency batteries.
A

Two (2) lead acid emergency batteries: one located up forward in LEER and one located back aft on left side of baggage compartment in Forward BEER.

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9
Q
  1. What are the three modes of emergency batteries?
A

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

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10
Q
  1. How are emergency batteries activated?
A

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

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11
Q
  1. What items are powered down to emergency batteries?
A

Emergency lighting Both SFDs

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12
Q
  1. When would 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.

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13
Q
  1. What additional function does right battery have on ground?
A

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

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14
Q
  1. What are main battery charging requirements?
A

AC power applied

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15
Q
  1. When is 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.

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16
Q
  1. What mode of battery/chargers is lost with loss of Main AC buses?
A

TR and charge mode

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17
Q
  1. The batteries have split bus configuration. What does that mean?
A

Left battery is involved in APU start; both batteries power aux pump.

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18
Q
  1. When should you remove batteries?
A

Cold soak conditions (-20°C)

19
Q
  1. On dark airplane, what occurs when EXTERNAL BATTERY switch is selected ON?
A

Power is provided from both main batteries and anti-collision beacon illuminates.

20
Q
  1. What’s the purpose of ground service bus (GSB)?
A

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

21
Q
  1. What are the sources of power for ground service bus?
A

Right main DC bus, external DC, or right battery.

22
Q
  1. Name the locations of four (4) GSB control switches.
A

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

23
Q
  1. What happens on dark airplane when GND SVC BUS switch is selected to ON?
A

Right battery powers ground service bus and anti-collision beacon illuminates.

24
Q
  1. There are four (4) GND SVC Bus annunciator lights: one in cockpit, one in Security / Gnd Svc panel, one in refuel panel, and one on ground service panel in tail compartment. When do they illuminate?
A

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

25
Q
  1. When is ground service bus automatically deactivated?
A

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

26
Q
  1. What’s the function of EBHA battery?
A

It’s dedicated source of power to Electric Backup Hydraulic Actuators (EBHAs).

27
Q
  1. What’s the purpose of UPS battery?
A

It’s dedicated source of power to flight control computers.

28
Q
  1. If both AC and DC external power is connected, which has priority?
A

External AC

29
Q
  1. Describe APU generator.
A

It’s mounted on APU, is usable on ground, or in flight. It’s physically and distinctly different from IDGs but produces same type of power.

30
Q
  1. What’s the source of power for personal electronic devices, electric razors, hair dryers, blender, toaster, etc.?
A

60 Hz power system comprised of two converters. One converter is active while other is standby.

31
Q
  1. 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 single switch for load shedding all power to cabin.

32
Q
  1. What’s the purpose of Secondary Power Distribution System (SPDS)?
A

It takes power from primary power system and distributes it to various aircraft loads.

33
Q
  1. SPDS is composed of two Electrical System Controllers (ESCs) and 14 Modular Power Tiles (MPTs) (4 for AC and 10 for DC). What’s the difference between ESCs and MPTs?
A

ESCs perform system control functions and interface with other aircraft systems. MPTs perform power routing and circuit protection functions using AC and DC Solid State Power Controllers (SSPCs).

34
Q
  1. What causes “AC” or “DC” legend of AC/DC RESET switchlight to activate?
A

Fault in AC or DC bus, logic fault within BPCU, or relay or component failure.

35
Q
  1. What happens when you depress RESET switch?
A

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

36
Q
  1. When would you select L/R Bus Tie to ISLN?
A

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

37
Q
  1. Describe RAT deployment.
A

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

38
Q
  1. What does 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 TRUs.

39
Q
  1. How is RAT stowed?
A

On ground using installed hand-operated piston pump mounted above RAT assembly: it cannot be stowed in flight.

40
Q
  1. What happens as airspeed falls below limit of RAT operation (200 knots)?
A

RAT stops operating and Main, UPS and EBHA batteries begin to power flight critical systems for up to 10 minutes.

41
Q
  1. When is AUX DC bus load shed or not powered?
A

During single generator operation, RAT generator operation, battery only operation, or when Aux TRU is powering another DC bus. Load shed feature is inhibited on ground.

42
Q
  1. Describe purpose of fifth or Aux TRU.
A

It serves as backup to primary TRUs. When not serving in backup role, Aux TRU powers Aux DC bus which provides 28 VDC power to cabin loads.

43
Q
  1. What’s Aux TRU priority?
A

Essential before main and left before right.

44
Q

Components

A

4 Generators: 2 Integrated Drive Generators (IDGs), APU generator, and Ram Air Turbine (RAT)
6 Computers: 2 Bus Power Control Units (BPCUs) and 4 Generator Control Units (GCUs)
5 Transformer Rectifier Units (TRUs)
6 Batteries: 2 main ship batteries, Electric Backup Hydraulic Actuation (EBHA) battery, Flight Control Uninterruptible Power Supply (UPS) battery, and 2 emergency batteries
2 Converters
2 Electrical System Controllers (ESCs)
14 Modular Power Tiles (MPTs)

Study Guide (17 decks)

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