Electrical

Question 1

What is the minimum acceptable battery voltage when performing a battery
integrity check?

Answer 1

22 volts DC

Question 2

What is the voltage and ampere rating of the batteries?

Answer 2

24 volts DC

40 ampere-hours

Question 3

With the battery switches selected ON and no other power on the aircraft,
which electrical buses are shown as powered on the EPMP?

Answer 3

Essential DC bus (powered by the batteries)

Essential AC bus (powered by the “E” inverter)

Question 4

With the battery power selected “ON” and no other power sources available,
what are the acceptable readings for the Essential AC and DC bus volts?

Answer 4

Essential AC bus – 115 volts AC, 400 Hz

Essential DC bus – 22-27 volts

Question 5

What buses are powered with either external battery switch selected ON?

Answer 5

Only the essential buses

ESS- DC = batteries, ESS AC bus (Phase A only) through the “E” inverter

Question 6

Where can information be found concerning items powered by the emergency
batteries?

Answer 6

QRH, Electrical System Abnormal Procedures tab (EA)

Question 7

How are the emergency batteries normally tested?

Answer 7

Arm the emergency battery switch with no other power on the aircraft

Question 8

Where are the feeder bus circuit breakers located?

Answer 8

On the power distribution box (PDB), in the right radio rack

Question 9

How is AC external power connected to the aircraft?

Answer 9

Select the AUX PWR switch ON with at least 1 battery switch ON

Question 10

11. What is the function of the battery override switch on the AC external power
    receptacle?

Answer 10

To connect AC power to the aircraft if the batteries are discharged or removed

Question 11

12. What buses are powered with external DC power connected?

Answer 11

All DC buses are powered ( ESS – DC, LEFT & RIGHT MAIN DC), and the ESS   
AC bus (Phase A only) through the “E” inverter

Question 12

13. What buses are powered with external AC power connected?

Answer 12

All buses are powered AND the batteries will be charged

Question 13

Is it possible to charge the batteries using DC external power?

Answer 13

No, the respective MAIN AC buses must be powered in order to charge the
batteries

Question 14

14. What is the output rating of the “E” inverter?

Answer 14

800 volt-amps

Question 15

15. What is a valid indication of “E” inverter operation?

Answer 15

Essential voltmeter switch-light selection on the EPMP and indications of
115 volts, 400 Hz

Question 16

16. What buses are powered by the “E” inverter?

Answer 16

Essential AC bus, phase “A” only

Question 17

17. What are the possible sources of power for the “E” inverter?

Answer 17

Whatever is powering the Essential DC bus

The standby electrical power system (HMG)

Question 18

18. What are the 2 main functions of the battery chargers?

Answer 18

To charge their respective battery
To provide a transformer-rectifier mode of operation for supplemental power if
necessary

Question 19

19. What buses supply power to the battery chargers?

Answer 19

Battery charger #1 (left) – LEFT MAIN AC BUS

Battery charger #2 (right) – RIGHT MAIN AC BUS

Question 20

20. Can one battery charger charge both batteries?

Answer 20

No, only its respective battery

Question 21

21. What is the maximum output of the battery chargers in transformer-rectifier
    mode?

Answer 21

50 amps each, for a total of 100 amps

Question 22

22. What situations would cause the battery chargers to operate in transformer-
    rectifier mode?

Answer 22

When the AUX hydraulic pump is selected on, or
APU start button is depressed, or
Selection of ESS DC Bus Battery Switch to “ON” (Manually or Automatically)

Question 23

23. What is the output of the converters?

Answer 23

AC output – 115 volts AC at 400 Hz, 23 KVA

DC output – 28 volts DC, 250 amps thus 28 X 250 = 7000 VA or & KVA

Question 24

24. If a converter failure occurs, what are the resulting indications?

Answer 24

The respective “AC POWER FAIL” and “DC POWER FAIL” amber CAS messages
will illuminate
The affected AC and DC buses will automatically switch over to the next available
power source

Question 25

25. What is the difference in the corrective action for a “DC POWER FAIL” CAS message versus an “AC POWER FAIL” CAS message?

Answer 25

If a “DC POWER FAIL” CAS message illuminates, converter operation may be continued and monitored If an “AC POWER FAIL” CAS message illuminates, the converter must be turned OFF because the cooling fans require AC power to operate

Question 26

26. If an amber “CONV FAN FAIL” CAS message occurs, what does this in?

Answer 26

At least one of the 5 converter fans have failed

Question 27

27. Is converter operation permitted with a converter fan inoperative?

Answer 27

Yes, for a designated period of time (25 hours)

Question 28

28. What is the immediate consideration with a dual converter failure in flight?

Answer 28

NAACP Symbol generator N- normal A- alternate A- alternate Fuel C- cross flow open P- single pump operation

Question 29

29. What is the engine-driven alternator output?

Answer 29

115 volts AC, 3-phase, 30 KVA

Question 30

30. Control of electrical current and auto-switching for AC and DC is supplied from what components?

Answer 30

AC and DC bus power control units (BPCUs)

Question 31

31. When might you use the standby electrical power system?

Answer 31

With Dual Converter Failure above 15,000 feet until you are able to start the APU alternator as a source of electrical power With an ESS DC Bus on battery power fault

Question 32

``` 32. What is the minimum HP % RPM to consider when using the standby electrical power system (HMG)? ```

Answer 32

67% HP RPM

Question 33

33. What are the considerations regarding the use of the SEPS for landing?

Answer 33

Do not use thrust reversers Do not use automatic ground spoilers (They will not be available with loss of Left Main DC) Maintain a minimum of 67% HP RPM (Engines will remain at 67% with loss of Main DC) Deploy the speedbrake handle slowly upon landing Turn the emergency batteries ON as a backup Landing Gear extension may cause the SEPS to go off line Be prepared to cycle the SEPS switch if it cycles off line

Question 34

34. What buses are powered when using the SEPS?

Answer 34

Essential DC bus (through the TRU) | Essential AC bus, phase “A” only (through the “E” inverter)

Question 35

35. During SEPS operation, why might the utility pump operate continuously if it is armed?

Answer 35

Because the control circuit is on the L MAIN DC bus, which may no longer be powered (utility solenoid shutoff valve fails to the OPEN position)

Question 36

36. What is the function of the TRU?

Answer 36

To convert AC power into DC power. Power the Left, Right Main DC and ESS DC buses during APU / EXT AC power operations, and power ESS DC bus during SEPS operations. It also acts as a backup to the DC converters in-flight.

Question 37

37. What is the maximum output of the TRU?

Answer 37

300 amps

Question 38

38. Where does the EPMP receive its power from?

Answer 38

From the remote power supply (RPS)

Question 39

39. On the EPMP, the left and right voltmeter selector switches allow the monitoring of what components?

Answer 39

The left and right converters

Question 40

40. The “ESS” power monitor switch on the EPMP, when selected, provides display information about which electrical power sources?

Answer 40

Essential DC and Essential AC bus voltages

Question 41

41. Why are the six EPMP “AUTO” bus switches selected under normal flight conditions?

Answer 41

To allow the bus power control units (BPCUs) to select the best available power source for each bus

Question 42

42. What is the normal power source for the Essential DC bus after engine start with both converter switches selected ON?

Answer 42

Whatever power source is providing power to the left main DC bus (normally the DC portion of the left converter)

Question 43

43. What is indicated by the battery ammeters on the EPMP?

Answer 43

Battery charge and discharge in amps

Question 44

44. What is indicated by an amber “EPMP POWER FAIL” CAS message?

Answer 44

At least one of the 4 input power sources to the remote power supply (RPS) has failed

Question 45

45. With a left converter failed, what is most likely power source for the L MAIN DC bus?

Answer 45

The TRU

Question 46

46. What power source normally provides power to the ESS DC bus in flight?

Answer 46

The DC portion of the left converter, through the L MAIN DC bus

Question 47

47. What power source normally provides power to the ESS AC bus in flight?

Answer 47

The AC portion of the left converter, through the L MAIN AC bus

Question 48

48. What is indicated by an amber AC or DC reset light?

Answer 48

A fault on an AC or DC bus

Question 49

49. Is it possible to start the APU using external DC power?

Answer 49

Yes, but the QRH must be referenced: Follow “APU” Starting using external DC power procedures in QRH in the APU operation (NB section)

Question 50

50. If the APU is running and the AUX PWR switch is selected ON, what would happen if both battery switches were selected OFF?

Answer 50

No change would occur, the APU alternator would continue to provide power to the main and essential buses

Question 51

51. What is the maximum allowable AC AUX PWR load indication prior to starting the TAY engine?

Answer 51

35 percent

Question 52

52. If the ESS DC BUS AUTO, LEFT MAIN and BATT switch light capsules are illuminated simultaneously in flight, what likely has occurred?

Answer 52

The K20 / K22 relay has experienced a failure of one of the relay poles, report for maintenance action