Electrical

Question 1

How long will the aircraft’s batteries last with no recharging?

Answer 1

10 minutes.

In an ELECTRICAL EMERGENCY, batteries are capable to supply airplane essential systems for at least 10 minutes, even if the RAT is failed.

Question 2

What is the purpose of the DC GPU receptacle?

Answer 2

For APU start when batteries are less than 22.0 VDC, or if battery temp is less than -20c

Question 3

What is the minimum battery temp for APU start?

Answer 3

-20c

Question 4

What is the minimum battery voltage to close the battery bus-ties?

Answer 4

18 Volts

Question 5

What battery is used for the APU start?

Answer 5

BATT 2 powers the APU Start Bus.

BATT 1 powers the FADEC and EICAS for monitoring

Question 6

What is the purpose of the Inverter?

Answer 6

Converts 28 VDC from the batteries to 115 VAC to power the AC STANDBY BUS when an AC source is not available so that 1A and 2A igniters always have a source of power.

Question 7

What is on the AC STANDBY BUS

Answer 7

Engine exciters 1A and 2A

Question 8

What powers the Ram Air Turbine (RAT)?

Answer 8

Airflow turns the RAT propeller which spins the turbine inside.

The RAT is an AC electrical device installed in the airplane nose section, which converts the kinetic energy of airflow across the turbine into AC power. The electrical power produced is rated at: 15kVA, 115V AC, 400Hz, three-phase.

Question 9

When will the RAT deploy?

Answer 9

Automatically deploys if AC BUSES are not powered.

Manually by pilot by using the Ram Air Deployment Handle.

Note: FLAP 3 max landing if RAT is deployed.

Question 10

How long after deployment before the RAT will supply power?

Answer 10

8 seconds

Whenever AC power sources are not powering AC Buses, the RAT is automatically deployed, and after 8s, supplies power to the AC ESS BUS

Question 11

Is there a total loss power during the 8 second RAT deployment?

Answer 11

No. Batteries supply power to the DC ESS BUSES and STBY AC BUS (through the Static Inverter).

To avoid total loss of power during this 8 second period, batteries are used as backup to power the DC ESS BUSES and the STANDBY AC BUS

Question 12

What does the RAT power?

Answer 12

AC ESS BUS
AC STBY BUS
(3) DC ESS BUSES
(2) HOT BATT BUSES

Question 13

What is the minimum airspeed for the RAT?

Answer 13

130 KIAS.
Load shedding occurs below this speed.

At speeds below this, the RAT may only supply the AC ESS BUS, and the batteries will automatically provide electrical power to the DC ESS BUSES and the STANDBY AC BUS through the Static Inverter (AC/DC Inverter). As airspeed decreases, load shedding occurs and the AC ESS BUS is no longer powered.

Question 14

How can you ensure the RAT has deployed successfully?

Answer 14

BATT DISCHARGING EICAS message will go away

Question 15

When is the RAT icon displayed on the electrical synoptic page?

Answer 15

When the RAT is deployed.

The RAT icon and its output (voltage and frequency) are displayed only when the RAT is deployed.

Question 16

What manages the electrical system?

Answer 16

4 ICC’s Integrated Control Centers (ICC).

2 SPDA’s Secondary Power Distribution Assemblies (SPDA)

Question 17

What is an ICC?

Answer 17

Integrated Control Center is an electrical control device, which provides power distribution and protection for electrical loads. (collects and confirms power is safe)

(1) Left Integrated Control Center (LICC). (2) Right Integrated Control Center (RICC). (3) Emergency Integrated Control Center (EICC). (4) Auxiliary Integrated Control Center (AICC)

Question 18

What is an SPDA?

Answer 18

An electrical load-management unit (powered by the ICC’s) that distributes electrical loads to aircraft systems according to distribution logic and performs BITs on many components.

Question 19

Can the flight crew reset the ICC and SPDA remote electronic CBs?

Answer 19

ICC CB’s can only be reset by maintenance.

SPDA CB’s can be reset via the MCDU.