Electrical Flashcards
What is an IDG?
Integrated Drive Generator
What are the components of an IDG?
Constant Speed Drive (CSD); Generator Control Unit (GCU) and a Generator
Where is the Main Battery located?
In the nose avionics bay
What is the purpose of a constant speed drive? (CSD)
Converts variable engine input speed to constant speed.
What is the purpose of the GCU?
- Regulates the IDG Generator
- Controls generator frequency and Volts
- Protects from over and under current
Basically it allows the generator to power AC electrical components if the VOLTS and FREQ are within limits
How is the GCU controlled?
Through the GEN 1/2 switches.
Where should the GEN 1/2 switches be in order to allow the GCU to manage the connection?
AUTO
What is special about the oil system of the IDG Drive Mechanism (CSD)?
It is independent from it’s associated engine
What is the IDG drive mechanism’s oils system monitored for?
HOTLOP
High oil temperature, low oil pressure
If the IDG drive mechanism’s Oil Temp/Press is not in limits how does the pilot know?
“IDG FAULT” light comes on.
What will cause the IDG to automatically disconnect?
An Over Torque or Over Temp condition of the CSD
Can the IDG be turned back on in flight?
Nope, can only be turned back on by MX on the ground
What do the different colors mean on the electrical synoptic page?
Green: NORMAL
WHITE: NOT ON/NOT NORMAL - ENGINE NOT RUNNING
YELLOW: OFF - WITH ENGINE RUNNING
Does the APU have a CSD?
No, the APU only has a generator control unit (GCU)
What will the APU’s GCU remove the APU’s power output for?
Over/under voltage
Over/under frequency
Generator and bus over current
Generator phase sequence
How can we check the status of the APU?
The AC Electrical Synoptic page
When the APU is started, what happens to external power?
It is automatically disconnected
Can the APU power all the AC buses?
Yup
If the APU is selected OFF with the APU available to provide electrical load, what will happen?
A caution light is generated on the EICAS
If no other power source is available, what will the APU provide?
AC power and bleed air to help start the engines
When the left engine’s IDG begins powering AC BUS 1, what will happen to the APU power output?
It will power AC BUS 2?
If both engine IDGs are providing power to their associated buses, what will the APU do?
It will automatically be disconnected and will not power any of the buses
If APU voltage is greater than ______, a _______ will be displayed on EICAS
40kva, CAUTION
External power is _______ to power the entire electrical system
Able
Where is the external power receptacle?
Forward right side of fuselage
How will you know if external power is available?
the AVAIL light will illuminate on the electrical power panel
You know that electrical power is being supplied by external power because…
- AC Switchlight will turn to “in use”
1. AC electrical synoptic flow lines are displayed in green from “EXT AC”
If you lose electrical power, what will happen to ensure that you still have a source of AC power?
The ADG will automatically deploy (air driven generator)
How will you know the ADG is deployed?
Warning will be generated
How can you manually deploy the ADG?
By pulling the manual deploy handle… duh
Is the ADG heated?
Yes, by an internal heater
when will the “ADG AUTO FAIL” EICAS status message display?
- A fault occurs in deploy control unit
- Unit is not powered
- Uplock solenoid has failed
What buses does the ADG supply power to?
The ADG BUS and AC ESS BUS
ADG BUS provides power where?
- 3B hydraulic pump
- Flaps and slats
- Pitch trim channel 2
Is there anything different If the flaps/slats are being powered by the ADG BUS?
Yes, they will move at HALF NORMAL speed
If either main generator is restored, the ADG can be Overriden by doing what?
Pressing the “PWR TXFR OVERRIDE” button
What will pressing the “PWR TXFR OVERRIDE” button do?
Will reconnect the restored Generator to power AC bus 1 and 2. the ADG will still power ADG BUS and critical flight controls
What is the minimum speed the ADG will work?
135 knots
If below 135 knots, what’s your only source of electrical power if both IDGs and your APU have failed?
The battery
How will you know if the GCU has failed on the ADG?
“ADG FAIL” status message
How is the ADG tested?
“Unit test switch”
When can you test the ADG?
Only can be done with two generators ON and both main AC buses powered
What indicates a successful test of the ADG system?
TEST light will illuminate if successful
What is the ACPC and what is it’s functions?
AC Power Center, it distributes AC Power to the four AC busses provides BUS PRIORITY LOGIC by changing the position of contractors depending on AC availability
What is the normal AC bus priority logic?
IDG 1 powers AC BUS 1
IDG 2 powers AC BUS 2
If an IDG fails in flight, what will happen?
Bus priority logic from the ACPC will automatically transfer load to the operable IDG
How will you know if the automatic transfer of an AC bus fails during an IDG failure?
“AC 1/2 AUTOXFER” EICAS caution displays and “AUTO XFER FAIL” message displays on the AC electrical page
If an IDG fails, and automatic transfer is not wanted, how do you disable it?
By hitting “AUTO XFER” switch lights
How will you know if AC BUS 1 or 2 is not powered?
EICAS message
What does the AC Essential Bus do?
Powers critical components that are vital to the safe operation of the aircraft
What normally powers the AC Essential bus?
AC BUS 1
What is the purpose of the AC ESS XFER Switch light?
To manually transfer the source of power for the AC ESS Bus from BUS 1 to BUS 2
What is the purpose of the AC service bus?
Used to power certain components needed to service the airplane
What does the AC Service Bus power?
APU charger Ac service feed Cabin lighting Logo lights Toilet Water system
What normally provides power to the AC Service BUS?
AC BUS 2
What will happen to the AC SERV bus during non-normal operations?
It will be shed in order to preserve power
How do you know the AC SERV BUS is being shed?
“AC SERV BUS” EICAS message and “SHED” in the AC Electrical Synoptic Page.
What is the purpose of the “EXT AC PUSH” Switchlight on the external service panel?
To energize AC SERV BUS without energizing the entire aircraft electrical system
What will happen if any aircraft generator is selected on while in the “SERVICE CONFIGURATION”?
It will override the service configuration
What provides DC Power?
- 4 TRUs
2. 2 Batteries
What is a TRU?
Transformer Rectifier Unit
What is the purpose of a TRU?
Converts 115Vac input power to 28 Vdc Output power
What powers the TRUs?
AC BUS 1
AC BUS 2
AC ESS Bus
What does it mean if the TRU is white in the DC electrical synoptic page?
TRU output has dropped below 3.7 amps or 18 volts. Status message will be generated “TRU 1 FAIL”
Where does power from the TRUs go?
- DC BUS 1
- DC BUS 2
- DC ESS BUS
- BATT BUS
- DC SERV BUS
- DC UTIL BUS
ESS TRU 2 is normally supplied power by ________
AC BUS 2
If AC BUS 2 fails, will ESS TRU 2 receive power? Why or why not?
Yes, because the ESS TRU 2 XFR contactor will switch, allowing the AC ESS BUS (which is being energized by AC BUS 1) to power ESS TRU 2
When will the DC ESS BUS caution display on the EICAS?
Bus is not powered in flight or…
Bus is not powered on the ground with either the AC ESS BUS or APU GEN on line
How many batteries the the CRJ have?
2
What kind of batteries the does the CRJ have and where are they located?
Nickel Cadium. the Main Battery is in the Nose Avionics Compartment and the APU Battery is in the tail aft equipment compartment
What provides DC Power?
4 TRUs
What does the APU Battery provide DC Power to?
The APU BATT DIR BUS.
How is the APU Battery charged?
APU battery charger
Where does the APU battery charger receive power from?
The AC SERV BUS
What are the specs for the APU BATT?
24 Vdc with a capacity of 43 amp-hours.
What does the Main Battery power?
The MAIN BATT DIR BUS
AC electrical specs
115 Vac
400 HZ
3 Phase
Where are the TRUs located?
In the nose
Main battery specs
17 Amp Hour
24 Volt
APU Battery Specs
43 Amp Hour
24 Volt
What does the DC Service Bus Power?
NAVs
LAVs
DOMEs
What is the minimum voltage before flight?
APU and MAIN should BOTH be above 22 volts or above
How long do we have from battery master on to provide AC power?
5 Min
When will the DC EMER Bus show up on DC Synoptic Page?
When it has a fault or lost it’s source of power from either of its two power sources (BATT BUS or APU BATT DIR BUS).
What does the DC EMERG BUS power?
FIDEEX
If the DC SERV switch is left on, what battery will begin to drain?
The APU
In flight, how much power will the batteries provide if they are the only source of power?
30 minutes
Where does the APU Battery charger get it’s power from?
The AC Service Bus
What drives the CSD?
The accessory gear box
Can we reconnect an IDG after it is disconnected in flight?
Nope
What will cause the GCU to trip the generator offline?
- Over Current
- Out of phase
- Over/under voltage
- Over/under frequency
What does it mean when the AC ESS XFER Switchlight is illuminated?
The AC ESS Bus is being powered from AC BUS 2
What causes the ADG to Deploy?
Lose power to Bus 1 and 2
When will the “EMER PWR ONLY” warning message pop up?
Only when ADG is only source of power
What does pulling the ADG handle ensure?
The DC essential bus remains powered. Prevents it from being load shed after airspeed decreases below 135knots
What is the purpose of the Essential TRU 2 contactor?
Powers TRU 2 If it’s normal source of power is not available and we need it. It does this by allowing AC ESS BUS to power ESS TRU 2 instead of AC BUS 2.
On BATT Power only, how many minutes do you have?
30 minutes
If on battery power only and you attempt starting the APU, how many minutes does that eat up of your 30 min available?
6 minutes per APU start attempt
How is DC power distributed through the system?
Two (DCPCs) DC Power Distribution:
L(LEFT)DCPC
R(RIGHT)DCPC
What is the purpose of the DCPCs and where are they located?
Located in avionics compartment in the nose
Job is to control contactor logic to connect various buses the the appropriate TRU depending on availability.
Describe the DC Essential Bus
Energizes equipment essential for safe flight. Due to this it can be powered by many different sources depending on availability.
Normally ESS TRU 1
if ESS TRU 1 fails, ESS TRU 2 through essential TIE
If ESS TRU 1 and ESS TRU 2 fail, TRU 2 through the CROSS TIE and Essential Tie
If ESS TRU 1 and 2 and TRU 2 fail, TRU 1 thru the MAIN TIE, CROSS TIE, and ESSENTIAL TIE
IF all TRUs fail, MAIN BATT DIR BUS and the APU BATT DIR BUS WILL POWER THE DC ESSENTIAL BUS through the DC Battery Bus
What happens when the DC SERVICE switch is selected ON?
The APU BATT DIRECT BUS powers the DC SERV bus. Can result in the APU BATT draining
What does the DC utility bus do?
Provides reading lights to passengers. Automatically shed when the Main Tie closes
What are all the HOT busses?
MAIN BATT DIR BUS
APU BATT DIR BUS
EMER BUS
What are the 2 specific scenarios that will energize the Essential TRU 2 CONTACTOR?
- On ADG power, ESS TRU 1 fails.
2. AC BUS 2 and TRU 1 fail.
