Electrical System

Question 1

What are two main components on the DC HOT BAT BUS 1 and 2 that we, as pilots, care about?

Answer 1

Engine fire protection system and refueling panel

Question 2

What type(s) of circuit breakers do(es) the E170 have? How do I access them?

Answer 2

Thermal and Electrical. Electrical CBs are found on the MCDU/FMS

Question 3

What is the primary purpose of a TRU?

Answer 3

Convert AC to DC

Question 4

In an electrical emergency, the batteries will provide at least ___ minutes of electrical power.

Answer 4

10 minutes, 2 APU Starts

Question 5

Briefly explain the purpose of the RAT

Answer 5

Provides emergency AC power in case of IDG/APU failure.

Question 6

A DC GPU can replace battery ___ in the event it is inoperative for APU starts.

Answer 6

Battery 2, only powers BUS 2 OR APU Start Bus. The DC GPU hookup only powers the APU Start BUS

Question 7

Can the AC STBY BUS start the engine?

Answer 7

Yes. It is powered from a DC Bus and Inverter which allows for engine start with no AC power.

Question 8

When Battery 1 is switched on what happens? What about Battery 2 to AUTO?

Answer 8

Battery 1 ON supplies power to the DC BUS 1 and the Hot Battery Bus.
Battery 2 automatically powers EITHER DC BUS 2 OR APU Start Bus

Question 9

Sources of AC power include…

Answer 9

2 IDGs, APU, GPU, RAT, Inverter

Question 10

What considerations are there when disconnecting an IDG?

Answer 10

Mechanically disconnects IDG from gear box and switch must be held in 1-3 seconds. A reset by Mx is required when disconnecting IDG

Question 11

What considerations are there when disconnecting an IDG?

Answer 11

Mechanically disconnects IDG from gear box and switch must be held in 1-3 seconds. A reset by Mx is required when disconnecting IDG

Question 12

What does the amber light on the IDG panel indicate?

Answer 12

System senses low oil pressure or high oil temperature. EICAS message will display

Question 12

What does the amber light on the IDG panel indicate?

Answer 12

System senses low oil pressure or high oil temperature. EICAS message will display

Question 13

What do the AC Bus Ties do? What happens when the switch is turned to 1 OPEN or 2 OPEN?

Answer 13

If one of the AC power sources fails, the AC Buses automatically connected by bus tie contactors (BTCs). One AC power source is sufficient to supply the whole system without significant degradation or additional workload.

1 OPEN: opens the Bus Tie Contactor (BTC) 1, segregating AC BUS 1 from AC BUS 2.

2 OPEN: opens the Bus Tie Contactor (BTC) 2, segregating AC BUS 2 from AC BUS 1.

Question 14

What happens to protect against an overload on the system if one AC power source fails?

Answer 14

The system will load shed the galleys and right windshield heat.

Question 15

What is “Electrical Power Priority?”

Answer 15

AC Bus 1 and 2 independently will seek out Onside, Inside, Outside, Cross-Side

Question 16

After starting the left engine with the APU on, what generator will power AC BUS 2? What powers AC BUS 1?

Answer 16

APU, IDG 1

Question 17

When the GPU AVAIL light comes on what does that mean?

Answer 17

“AVAIL” is displayed when the AC power meets the specific quality requirements (voltage, amperage, and frequency).

Question 18

How long does it take the RAT to deploy and begin producing AC Power?k

Answer 18

8 seconds, will automatically deploy and can be manually extended. During the powerup the batteries supply essential loads for 10 minutes

Question 19

What AC BUS does the RAT connect to?

Answer 19

AC ESS BUS

Question 20

What items are on the AC ESS BUS?

Answer 20

AC Fuel Pump 2A, ACMP 3A, SF-ACE 1 Flap, and SF-ACE 2 Slat

Question 21

What EICAS message should go away when the RAT deploys?

Answer 21

Batt Discharge

Question 22

What speeds are required to get the RAT spinning and to keep it spinning?

Answer 22

150 to get the RAT spinning, 130 to keep the RAT spinning

Question 23

What kind of batteries do we have in the ERJ 175?

Answer 23

2 Sealed Lead Acid Batteries (SLABs) at 24V in a 28V system