Electrics

Question 1

What are the ratings of the IDGs and APU?

Answer 1

Engine IDGs and the APU Generator are rated at 40kVA, 115VAC, 400Hz (3 Phase) (B12 14-05-10 Pg 1).

Question 2

What normally supplies AC ESS bus?

Answer 2

AC BUS 2 (B12 14-05-40 Pg 2)

Question 3

What are the alternate and emergency supplies for the AC ESS bus?

Answer 3

Alternate: AC BUS 1. Emergency: RAT (electrical emergency) (B12 1405-40 Pg 2)

Question 4

When will the RAT deploy automatically?

Answer 4

Whenever AC power sources are not powering AC buses, the RAT is automatically deployed, and after 8 s, supplies power to the AC ESS BUS. (B1214-05-10 Pg 4)

Question 5

Where is the battery voltage displayed?

Answer 5

On the MFD Electrical Synoptic Page (B12 14-05-05 Pg 7) and the MFD Synoptic Status Page (B12 14-05-05 Pg 12)

Question 6

In an ELECTRICAL EMERGENCY with the RAT failed, for how long will the batteries supply essential systems?

Answer 6

In an ELECTRICAL EMERGENCY, while the RAT is not fully deployed and also if RAT stall speed is reached, batteries supply essential loads for 10 min. (B12 14-05-15 Pg 2)

Question 7

What indications will be seen when the Battery temperature rises above 70 degrees C for longer than 2 seconds?

Answer 7

Whenever the battery temperature reaches 70°C for at least 2 s, the associated indication becomes red and the EICAS WARNING message BATT 1 (2) OVERTEMP is triggered. (B12 14-05-15 Pg 2)

Question 8

What is the minimum IAS for RAT operation?

Answer 8

130 kt is required to ensure the RAT continues supplying AC/DC ESS BUSES. (B12 14-05-10 Pg 4)

Question 9

In flight on battery power only, which electrical busses may be powered?

Answer 9

HOT BATT BUS 1, HOT BATT BUS 2, APU START BUS, DC ESS BUS 1/2/3, AC STBY BUS (via DC BUS 1 and DC INVERTER) (B12 14-0540 Pg 5)

Question 10

What does the avail light on the electrical overhead panel mean?

Answer 10

Illuminates inside the button when the AC GPU is connected to the airplane and AC power quality requirements (voltage/amperage/frequency) are satisfied. (B12 14-05-05 Pg 3). Ground staff can connect the GPU directly to the AC/DC GND SVC BUSES for ground maintenance and flight preparation, by pushing the respective button located on the front ramp panel or on the flight attendant panel at the forward right galley. (B12 14-05-10 Pg 3)

Question 11

What is No Break Power Transfer (NBPT)?

Answer 11

The E-Jets Electrical System has a protection feature, the NBPT, which avoids electrical transient in case of power transfer when the airplane is on the ground. The NBPT allows the momentary paralleling between two AC power sources: the IDGs, GPU and the APU generator, at any possible combination.

After achieving the auto-parallel condition, the system is able to parallel the sources for a short period (milliseconds). If the system does not achieve the auto-parallel requirements within the allowed time delay, the transfer will be concluded with a break-transfer of minimum power interruption. (B12 14-05-10 Pg 5)

Question 12

What is the rating of the RAT? What hydraulic pump does it power?

Answer 12

15kVA, 115 V AC, 400Hz

ACMP 3A

Question 13

What does the AC system compose of?

Answer 13

• 2 IDGs
• 1 APU
• 1 Inverter
• 1 RAT
• 1 external AC receptacle

Question 14

What does the DC system compose of?

Answer 14

• 2 NiCd batteries
• 3 TRUs
• 1 APU external DC receptacle

Question 15

What conditions cause the IDG amber LED to illuminate indicating that the IDG needs to be disconnected? When does automatic IDG disconnection occur?

How long should the switch be held in this position to disconnect the IDG?

Answer 15

Oil pressure - below 140 psi +/- 25 psi
Oil Temperature - 335F +/- 10F (168C +/- 5C)

Automatic disconnection - Oil temp reaches 366F (185.6C)

1 Second

Question 16

What does a green battery icon mean? and white?

Answer 16

Green: Voltages are greater than 18V
White: Voltages are less than 18V

Question 17

What speed is required to ensure the RAT does not stall?

Answer 17

130kts

Question 18

What is the rating of the TRU?

Answer 18

300A

Question 19

What is the rating of NiCd Batteries ?

Answer 19

22.8 V DC and 27A

Question 20

On ground if the AC is powered by only the batteries how long until the horn sounds?

Answer 20

5 minutes

Question 21

What is the electric source priority for the AC?

Answer 21

• Respective IDG
• APU
• GPU
• Opposite IDG

Question 22

What are the components turned off during load shedding?

Answer 22

• Galleys
• Right Windshield Heating

Question 23

In case of TRU failure what happens?

Answer 23

Respective DC BUS is automatically powered connected to the DC network through both essential Tie contactors (ETC) and a DC tie contactor (DCTC) according to the system logic

Question 24

What happens in a total loss of AC power event?

Answer 24

RAT automatically deploys

Question 25

What is the secondary power source for abnormal ground and flight operations?

Answer 25

APU

Question 26

When the aircraft electrical system is only on main batteries from where is the AC power generated for the AC STBY BUS?

Answer 26

Static Inverter

Question 27

How can flight crew visually monitor the remote circuit breakers inside the electronica bay?

Answer 27

MCDU CB page

Question 28

In the event of an electrical emergency, which instruments are powered directly from the DC ESS busses?

Answer 28

Pilots MFD, Pilots CCD, Co pilots MCDU, the EICAS and the Pilots Display Controller

Question 29

In the event of an electrical emergency where the RAT fails to deploy, which message will be displayed on the EICAS?

Answer 29

BATT Discharging

Question 30

Whenever the AC power sources (IDG or APU gen) are not powering AC buses, and the AC is on batters only, what will provide AC ESS BUS power in flight?

Answer 30

RAT