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76 Cards in this Set
- Front
- Back
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What components power the AC system?
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2 Integrated Drive Generators APU RAT Inverter AC GPU
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What happens if a power generating source fails?
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Bus ties automatically connect to provide no system degradation
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How many networks make up the electrical system on the airplane? Why?
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2 independent networks
Redundancy |
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What components power the DC system?
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2 NiCad batteries
3 TRUs DC GPU |
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How does the IDG maintain a stable power output?
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A Constant Speed Drive (CSD) attaches the IDG to the Accessory Gear Box (AGB)
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What monitors and controls the IDG's?
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Each has a Generator Control Unit (GCU)
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Can 1 IDG supply power for the entire electrical system?
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Yes
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What will cause the amber IDG light on the overhead panel to illuminate?
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High oil temperature Low oil pressure
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If an IDG is manually disconnected can it be reconnected by the flight crew?
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No, this is a maintenance function
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What is the primary purpose of the AC generators?
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To power the AC BUSSES and AC ESS BUS which power the 3 TRUs (TRU1, 2, & ESS)
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What is the purpose of the Transformer Rectifier Units (TRUs)?
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To convert 115 VAC to 28 VDC
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Can the APU replace a failed IDG?
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Yes
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What is the AC electrical system's priority?
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Onside (IDG)
APU GPU Cross-Side IDG Note - The aircraft uses an onboard AC power source before an external AC power source. |
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How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?
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GPU button displays AVAIL and the GPU icon is presented on the electrical synoptic page. Once the GPU button is pushed in, the button will display IN USE
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What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?
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Ground service bus is in use. Cockpit GPU button will display AVAIL even though the ground service bus is in use.
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If the airplane is using the AC GPU and the APU is started, what should the pilot be sure to do?
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Deselect the GPU button before the next GPU connection
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How long will the aircraft's batteries last with no recharging?
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10 minutes
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What is the purpose of the DC GPU receptacle?
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For APU start when batteries < 22.5 VDC OR If battery temperature is, -20ºC
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What is the minimum battery voltage to close the battery bus-ties?
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18 volts
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What battery is used for the APU start?
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Battery 2 powers the APU Start Bus
Battery 1 powers the FADEC & EICAS for monitoring |
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What is the purpose of the Inverter?
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Converts 28 VDC from the batteries to 115VAC to power the AC STANDBY BUS when an AC source is not available
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What is on the AC STANDBY BUS?
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Engine exciters 1A and 2A
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What powers the Ram Air Turbine (RAT)?
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Airflow turns the RAT propeller which spins the turbine inside
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When will the RAT deploy?
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Automatically deploys if the AC BUSSES are not powered OR Manually by pilot
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How long after deployment before the RAT will supply power?
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8 seconds
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When is the RAT icon displayed on the electrical synoptic page?
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When the RAT is deployed
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What manages the electrical system?
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4 Integrated Control Centers (ICC)
2 Secondary Power Distribution Assemblies (SPDA) |
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What is an ICC?
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An Electronic control device, which provides power distribution and protection for electrical loads
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What is an SPDA?
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An electrical load-management unit (powered by the ICCs) that distributes electrical loads to aircraft systems according to distribution logic
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Can the flight crew reset the ICC and SPDA remote electronic CBs?
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ICC CB's can only be reset by maintenance on the ground SPDA CB's can be reset via the MCDU
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Does battery 1 supply power when BATT 1 selector is OFF?
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Yes, it supplies power to the HOT BATT BUS 1
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What occurs when the BATT 1 selector is placed in ON?
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The battery 1 is connected to DC ESS BUS 1
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What occurs when the BATT 2 selector is placed in AUTO?
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Allows auto operation. The battery 2 connects to DC ESS BUS 2
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What does the AUTO position of the DC BUS TIES switch do?
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Allows auto operation of the DC TIE Contactors IAW system logic
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What does the OFF position of the DC BUS TIES switch do?
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Opens all DC Bus Tie Contactors
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Are the IDG ICONS on the MFD always in view even when the IDGs are not powered?
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Almost always. They become 3 dashes if invalid or out of range. Otherwise they are always in view.
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What are the IDG colors on the MFD when the IDG is available and the selector knob is in AUTO? OFF? (or engine not running)?
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Green in auto and white in off or when engine is not running
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Will the AC APU ICON always be in view on the MFD?
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No, only when the APU is available (3 sec after 95%)
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What does a white APU ICON beneath an Amber cross mean?
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The APU has failed and there will also be an EICAS message
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The Battery ICON is always displayed on the MFD. How can you tell if the voltage is good?
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The parameters are indicated (Voltage and Temp). Also the battery icon is green above 18 volts and white below 18 volts
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What does it mean when the battery associated digits turn RED on the MFD?
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The battery temperature reached 70ºC for 2 seconds. The BATT 1 (2) OVERTEMP EICAS message is also displayed
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When is the DC External GPU power used?
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Only to start the APU
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When is the RAT ICON displayed?
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Only when the RAT is deployed
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How many KVA does each IDG or APU supply? How about RAT?
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The IDG and APU are 40 KVA each.
The RAT supplies only 15 KVA |
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When will the RAT deploy automatically?
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When both AC BUSES 1 and 2 are not powered in flight
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What does the RAT power?
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Powers the AC and DC ESS Buses
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What are the primary and alternate sources of power for the AC ESS BUS?
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Primary is the AC BUS 2. Alternate is AC BUS 1 The RAT when both AC Buses 1 and 2 are not powered
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What has AC priority, the APU or GPU?
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The APU has priority and will automatically switch when the APU is up and running
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What powers the APU start bus during APU start?
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The BATT 2 and it is isolated from the network powering the start bus exclusively
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What is required before disconnecting the AC GPU even if the AVAIL light is illuminated?
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PUSH OUT the AC GPU button so the power can be connected the next time it is used. Going from out to in closes the generator relay
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What is the normal and alternate source of power for the AC Standby Bus?
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Normal is the AC ESS BUS and the alternate is the AC Inverter
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What supplies the power during the 8 seconds it takes the RAT to provide power following RAT deployment?
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The batteries power the DC ESS BUSES and the STANDBY AC BUS thru the AC Inverter
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Is their an altitude restriction for RAT deployment?
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No
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What is the minimum airspeed for the RAT?
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130 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 an AC/DC inverter. As airspeed decreases, load shedding occurs and the AC ESS BUS is no longer powered.
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During normal operations, TRU 1 supplies power to what?
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DC BUS 1
DC ESS BUS 1 DC Ground Service Bus HOT BATT 1 BATT 1 charging |
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During normal operations, TRU 2 supplies power to what?
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DC BUS 2
DC ESS BUS 2 HOT BATT BUS 2 BATT 2 charging |
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During normal operations, TRU ESS supplies power to what?
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DC ESS BUS 3
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When are the batteries being charged?
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Whenever the TRUs are powered from AC source
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How long do the batteries last during an electrical emergency?
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About 10 minutes
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What is the minimum temperature required on BATT 2 for APU Start?
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-20ºC
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What would you do if the BATT 2 was colder than -20 C?
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Connect the DC GPU which powers the APU Start BUS and isolates the BATT 2.
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Briefly describe the electrical power distribution and control system
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There are four ICCs (integrated control centers) and Two SPDAs (secondary power distribution assemblies)
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Name the four ICCs:
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LICC
RICC EICC AICC (left, right, essential & aux) |
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These ICCs are located where?
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In the E-bays
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What do the ICCs contain?
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Line replaceable units and modules, thermal circuit breakers, and the AC/DC Buses including essential buses and hot battery buses.
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Which ICC houses the HOT BATT 2 and the APU Start Bus?
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Its the AICC (aux ICC)
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Each SPDA has specific slots that house what?
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Electronic modules that provide associated functions such as COMM, data processing and power distribution. The MAU does the thinking, the ICCs provide the power and the SPDAs do the switching
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Four independent DC Buses power each SPDA. Which buses power SPDA 1?
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DC BUS 1
DC ESS BUS 1 DC ESS BUS 2 DC GND SVC BUS |
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Four independent DC Buses power each SPDA. Which buses power SPDA 2?
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DC BUS 2
DC ESS BUS 1 DC ESS BUS 2 DC GND SVC BUS |
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How can the flight crew reset the SPDA remote electronic CBs?
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Via the MCDU.
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The IDGs and Apu are rated at how many kVA, VAC, Hz?
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40 kVA
115 VAC 400 Hz |
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The RAT is rated at how many kVA, VAC, Hz?
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15 kVA
115 VAC 400 Hz |
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How many Amps is the TRU rated at?
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300A
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How many volts and amps are the batteries?
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Two NiCd 22.8 VDC 27 A
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How many volt amps is the Inverter?
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250 VA
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What is on the DC ground service bus?
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Lights:
Cargo Compartment Entrance Lav Galley Service Compartment Courtesy Flash Light Charger Water/Waste controller SPDA pwr supply |
