Electrical

Question 1

Which bus control unit controls External AC, DC?

Answer 1

Left BPCU controls Ext AC

Right BPCU - Ext DC

Question 2

What is the rated output of the RAT?

Answer 2

15 kVA.

Question 3

E-Batts will trigger on if ARM’d if:

Answer 3

Voltage on either ESS DC buses drops below 20 Volts

Question 4

What do you need to energize (power) the Main Battery Chargers?

Answer 4

MAIN AC BUS powered (Generator/APU/Ext AC)

Battery Switches - “ON”.

Question 5

Which BUS powers the EBHA and UPS battery chargers?

Answer 5

Left Main AC Bus

Question 6

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

Answer 6

1. Fault within Main AC bus or Emergency AC
2. Logic fault within BPCU
3. Relay or Component Failure

Question 7

Why does transfer of power between Ext AC and the APU result in BPT?

Answer 7

APU gen and Ext AC power are not frequency controlled by GCU and BPCU. (No IDG involved)

Question 8

What three ways are the 60 Hz converters controlled?

Answer 8

1. Cabin/Galley Master push button
2. 60 HZ Master Push Button
3. SSPC on any MCDU

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

When should you remove the batteries?

Answer 11

When parked in a cold soak condition (<-20°C)

Question 12

When would MAIN BATTERY switches indicate amber ON?

Answer 12

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

Question 13

What additional function does the right battery have on ground?

Answer 13

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

Question 14

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

Answer 14

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

Question 15

What’s the purpose of UPS battery?

Answer 15

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

Question 16

Describe the emergency batteries.

Answer 16

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

Question 17

What are the three modes of emergency batteries?

Answer 17

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

Question 18

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

Answer 18

Right main DC bus, external DC, or right battery

Question 19

SPDS is composed of two (2) 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?

Answer 19

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

Question 20

How long do the E-Batts provide power?

Answer 20

45 Minutes