Electrical Flashcards
What is an IDG? How many are on the E175?
Integrated Drive Generator, 2
What is the IDG output?
115VAC, 400Hz, 40KVA
What is the APU output?
115VAC, 400Hz, 40KVA
What does the GPU stand for? What is the GPU output?
Ground Power Unit, 115VAC, 400Hz, 40KVA
What is the RAT? What is the RAT output?
Ram Air Turbine, 115VAC, 400Hz, 15KVA
How many inverters are on the E175? How many VAC is the inverter?
1, 250VAC
What is the purpose of an inverter?
Converts VDC to VAC
When can the IDG power both AC buses?
On the ground and in flight
When can the APU power both AC buses?
On the ground and in flight up to FL330
Can the GPU power both AC buses?
Yes
What is the primary source of AC power?
IDGs
What happens when the IDG knob is in the AUTO position?
system logic controls contactor
What happens when the IDG selector knob is turned OFF?
opens contactor to break the circuit disconnecting the IDG from the electrical network
What happens when the IDG DISC position is selected?
This position mechanically disconnects the CSD (Constant Speed Drive) from the IDG
Can the flight crew reconnect the IDG after IDG DISC?
No, only maintenance can reconnect the IDG
Amber light accompanied by the EICAS oil message indicates
IDG disconnect is required due to High Oil Temperature or Low Oil Pressure
What are the secondary sources of AC power?
The APU, the GPU
What power source is required to start the APU?
DC Power is required
Either BATT 1 and BATT 2 or BATT 1 and DC GPU are required for APU start
What is the function of BATT 1 and BATT 2 for APU start?
BATT 1 controls the APU’s FADEC; BATT 2 is isolated from the network to exclusively power the APU START BUS
What is the minimum VDC for APU start?
22 VDC minimum must be noted during the Safety and Power On Checklist to consider APU start
What is the minimum VDC required to close the battery contactor during APU start?
18 VDC minimum required to close the battery contactor (connect the APU to the electrical network)
What is the minimum BATT 2 temperature required for APU start?
-20 degrees Celsius
What 3 methods/locations that can be used to turn on the GPU?
- AC GPU panel (powers AC&DC ground service buses and TRU1)
- Opposite the FWD lav (powers AC&DC ground service buses and TRU1)
- Cockpit overhead panel (powers whole aircraft network)
What are the messages/annunciations you will see if the parking brake is released with the GPU connected?
CAS message: GPU CONNECTED; Master Caution and aural warning
What CAS message will you see if the GPU is connected and power meets system requirements?
AVAIL
What CAS message will you see if the GPU is running and is the priority (powering the AC system)?
IN USE
What is the normal AC electrical priority?
- Onside (IDG)
- Inside (APU)
- Outside (GPU)
- Cross-Side (Other IDG)
What does the inverter power?
The inverter powers the AC STANDBY BUS when the normal AC power source is not available so that “A” igniters always have a source of power
What is the purpose of the RAT?
Emergency AC power source
Are there any altitude or airspeed restrictions for RAT deployment?
No
When does the RAT deploy and what does the RAT power?
The RAT automatically deploys if both AC buses lose power during flight (electrical emergency) to supply the ESS buses
Can the RAT be deployed manually?
Yes via the RAT Manual Deploy Lever
During RAT deployment, what source provides aircraft power?
The batteries provide power for approximately 8 seconds
What minimum airspeed is required for RAT operation?
130kts
What happens if the aircraft speed is below the minimum required (130kts) while the RAT is deployed?
The RAT will only provide power to the AC ESS bus; the BATTS will provide power to DC ESS bus and AC STANDBY bus; As airspeed decreases, load shedding occurs until AC ESS bus is no-longer powered
What sources provide the aircraft’s DC power?
3 TRUs, 2 Batteries, 1 DC GPU
What is a TRU?
Transformer Rectifier Unit, Converts AC to DC and can change the voltage
What is the output of the TRUs?
28 VDC, 300 A
What is the output of the batteries?
24 VDC, 27 AH
What is the output of the DC GPU?
28 VDC
What is the primary source of DC power?
TRUs
The TRUs convert ___ to ___
115 VAC to 28 VDC
Do the TRUs work together?
No, the TRUs work in isolation from each other
What is the secondary source of DC power?
The batteries
What type of batteries do we have?
NiCad (Nickel-Cadmium as electrodes)
How are the batteries charged?
Via any power source through the TRUs
What is the volt minimum to close the battery contactor?
18 Volts
How long will the batteries provide power during an electrical emergency?
10 minutes
What does the DC GPU connect to?
the APU start bus and replaces BATT 2 during APU start
How can the DC GPU be turned on?
By the button on the ramp
Can the DC GPU charge BATT 2?
No