Electrical

Question 1

Where does the AC power normally come from

Answer 1

AC ​power ​ can ​ be ​ supplied ​ by ​ two ​engine-driven ​ generators, ​an ​APU-driven ​generator, ​ and ​an ​external ​ power ​source.

Question 2

Where does the DC power normally come from

Answer 2

DC ​power ​ is ​ supplied ​ by ​ Transformer ​Rectifier ​ Units ​(TRU) ​1, ​2, ​ESS, ​and ​Ground ​ Service, ​ which ​ are ​ powered ​ by ​the ​ respective ​AC ​bus.

Question 3

What buses does the AC normally supply

Answer 3

AC buses 1&2, ESS AC BUS, EMER AC BUS, AVIONICS TRANSFER BUS, GALLEY BUSES 1&2, AC GROUND SERVICE BUS

Question 4

What buses does the DC normally supply

Answer 4

DC BUSES 1&2, DUAL DC BUS,ESS DC BUS, EMERDC BUS, DC GROUND SERVICE BUS, DC GROUND HANDLING BUS

Question 5

If all AC generator power is lost , what power is still available

Answer 5

Only battery power is available

Question 6

What alert is presented in this situation, where will the alert be shown

Answer 6

AC supply on the SAP

Question 7

How long would you expect the batteries to last if you loose all generators

Answer 7

30 mins or 60 mins respectively

And 1 APU start attempts

Question 8

On the ground how can the ground handling and ground service buses be powered

Answer 8

DC​ Ground​ Service Bus​ ​​ ​The AC​ ground​ service bus​ supplies, via a ground​ service TRU,​ the​ DC​ ground service bus.​ ​When​ the​ AC​ power is​ not available,​ the​ DC​ ground service bus​ can be​ powered by​ an​ external​ ​DC​ power​ source.​ ​​ ​DC​ Ground​ Handling​ Bus ​​ ​The AC​ ground​ service bus​ supplies, via the​ Ground Service TRU​ the​ DC​ ground handling bus.​ ​When​ no​ AC​ power​ is​ available the​ DC​ ground handling​ bus​ is​ supplied directly​ by​ the batteries.​ ​The ground handling​ bus​ supplies power​ to:​ ​
AC bus 2 supplies AC ground service bus

Question 9

When external AC is plugged in, but not switched on what is powered and what indications would you get

Answer 9

When AC​ external power is​ connected and within​ ​limits,​ the​ AVAIL​ light in the external​ power​ p/b is​ ​on, ​ the​ ​ AC ​ GROUND​ ​ SERVICE ​ light​ ​ at​ ​ the ​connector is on, and​ the AC ground service bus is ​energized.​

Question 10

On engine start, when do engine generators normally come online

Answer 10

When​ voltage​ and​ frequency​ are​ within​predeterminedlimits,theGCUautomaticallyconnects​thegeneratortothelineandautomaticallydisconnects​thegeneratorfromthelineifafailureisdetected.Ifthe​IDGoiltemperaturebecomesexcessive,analertwillbe​presented.Ifthetemperaturecontinuestoriseabove​a​ predetermined​ value,​ the​ IDG​ will​ be​ disconnected​fromtheenginedrive.

Question 11

What is an IDG

Answer 11

Integrated drive generator

Question 12

What is a GCU and what does it do

Answer 12

TheIDGoutputiscontrolled​byaGeneratorControlUnit(GCU)andthegenerator​p/b.​ When​ voltage​ and​ frequency​ are​ within​predeterminedlimits,theGCUautomaticallyconnects​thegeneratortothelineandautomaticallydisconnects​thegeneratorfromthelineifafailureisdetected.

Question 13

If an IDG overheats, what happens and what indication do you get

Answer 13

Ifthe​IDGoiltemperaturebecomesexcessive,analertwillbe​presented.Ifthetemperaturecontinuestoriseabove​a​ predetermined​ value,​ the​ IDG​ will​ be​ disconnected​fromtheenginedrive. You get a level 1 alert and display on MFDU

Question 14

Is the APU generator equipped with a constant speed drive

Answer 14

The​ APU​ generator​ is​ not​equipped​ with​ a​ constant​ speed​ drive​ since​ the​ APU​runsataconstantspeed.

Question 15

If external AC power is online and parameters go out of limits, what will happen

Answer 15

The​ Ground​ Power​ Control​ Unit​ (GPCU)​automaticallydisconnectstheexternalpowerfromthe​electricalsystemifitsparametersarenotwithinlimits.

Question 16

From which generators do AC buses 1 and 2 normally receive power

Answer 16

GEN 1supplies AC bus 1

GEN 2 supplies AC bus 2

Question 17

When is the automatic AC cross-tie inhibited

Answer 17

TheautomaticcrosstiefunctionforACbuses1and2is​inhibitedduringautomaticlandings.. Also inhibited when turned off or faulted

Question 18

What buses remain powered after the ESS+ EMER PWR ONLY push button is pressed

Answer 18

the​ essential​ AC​ bus​ and​ the​emergencyACbusremainenergized. ESS DC and EMER DC ALSO

Question 19

What are the power source priorities for the ESS AC bus

Answer 19

GEN 1 , GEN 2, APU, AC EXTERNAL POWER.

Question 20

From where can the EMER AC bus obtain power

Answer 20

Under​ normal​ power​ conditions,​ the​ EMER​ AC​ bus​ is​suppliedbytheESSACbus.IfACsuppliesfailandthe​AC​ buses​ 1​ and​ 2​ and​ the​ ESS​ AC​ bus​ become​ de‐​energized,theEMERACbusissuppliedbythebatteries​viaanEMERinverter.

Question 21

When is the galley power shed automatically

Answer 21

In​ flight​ during​ single​ generator​operation,​ the​ galley​ buses​ are​ automatically​ de‐​energized.

Question 22

You are airborne and GEN 1 goes offline. The APU generator is not available, what happens, And if the APU generator is available

Answer 22

Gen 2 will supply AC power tho the whole system

If APU Gen is available then it takes the place of Gen 1 and supplies power to AC bus 1

Question 23

What happens if a TRU fault occurs, what might the fault be

Answer 23

The TRU’s​ are​ ​automatically​ disconnected in​ case​ of​ overheat or​ reverse​ current.​ ​ If​ TRU​ 1 or​ 2​ should fail​ an​ ​alert​ will be​ presented. MCL DOUBLE CHIME AND AMBER FAULT ON MFDU AND LOCAL ALERT.

Question 24

What does the dual DC bus supply and for what purpose

Answer 24

DC​ buses 1​ and​ 2​ supply​ the dual​ DC​ bus. ​ It​ provides an​ uninterrupted​ power source for​ the​ lift ​dumpers,​ anti-skid,​ and​ speed brake in​ the​ event of​ a​ DC bus​ 1 or​ 2​ failure​ during​ landing

Question 25

What can be powered by the batteries alone

Answer 25

The ground handling bus. EMER DC , EMER AC

Question 26

How can the DC buses be tied together

Answer 26

Manual​ operation ​of the​​ ​DC​ X-TlE​ p/b​ interconnects​ the​ DC​ buses.​

Question 27

If the ESS TRU becomes inop, where does ESS DC get its power from

Answer 27

lf​ the​ ESS​ TRU is​ inoperative DC ​bus​ 1 will supply​ the ESS​ DC​ bus.​ ​ lf​ the​ ESS​ DC​ bus​ becomes​ de-energized an​ alert​ will be ​presented

Question 28

Where does EMER DC bus get its power from

Answer 28

The ES​ AC​ bus​ supplies,​ via ESS​ TRU,​ the​ EMER DC​ bus.​ ​ lf​ the​ ESS​ TRU​ is​ inoperative ​the​ EMER​ DC​ bus​ is​ automatically​ supplied by​ DC​ bus​ 1.​ ​ When no​ AC​ power​ is​ available​ the​ ​EMER​ DC​ bus​ is​ automatically​ supplied​ by​ the batteries

Question 29

What does DC ground handling bus supply

Answer 29

The ground handling​ bus​ supplies power​ to:​ ​​ ​-​ ​ Passenger​ door​ (if​ installed) ​-​ ​ Fuelling​ panel​ ​-​ ​ Towing​ ​-​ ​ Hydraulic​ service​ panel​ ​-​ ​ Engine​ starter​ valve​

Question 30

What can be powered from external DC and what are the indications you get

Answer 30

Adjacent​ to​ the​ external​ AC​ receptacle is​ a​ 28​ V DC​ receptacle​ to​ provide​ power to​ the​ DC ​ground​ service bus​ and​ the APU​ starter. ​ There are no​ controls​ or​ indicators in​ the​ flight deck ​related to​ DC​ external power

Question 31

How do you remove power from a PRAM system

Answer 31

Cabin Equipment’​ includes​ components of​ the ​ ​MP3​ (PRAM) System​ and the​ Flightdeck​ USB ​ ​Power Outlet System. Power is​ removed​ with ​ ​the checklist item​ “Galley​ PWR……OFF”.​ ​

Question 32

Through which bus is the Flightdeck USB power outlet powered

Answer 32

DC BUSES 1&2