Section 02 - Electrical

Question 1

Where does the 300-amp, 28-volt TRU receive its power from?

Answer 1

Either the LEFT or RIGHT MAIN AC bus, or the HMG

Question 2

If the co-pilot PHASE A circuit breaker on the RIGHT MAIN AC bus section of the PDB is tripped, what document can be used to determine inoperative equipment?

Answer 2

QRH Supplemental Procedures & Data (Section S)

Question 3

What is indicated by an amber “AC RESET” indication on the EPMP?

Answer 3

An AC bUS fault is indicated

Question 4

What buses can be powered by the Standby Electrical Power System (HMG)?

Answer 4

ESS DC, and ESS AC (phase A only)

Question 5

What is the restriction on converter operation with a fan inoperative?

Answer 5

Continued operation for a maximum of 25hrs is permitted, as long as only 1 cooling fan has failed.

Question 6

What indication and automatic action will occur if a left converter fails?

Answer 6

The amber “ L AC POWER FAIL” and “L DC POWER FAIL” CAS messages will be displayed, and the LEFT MAIN AC/DC buses will switch over to the next available power source.

Question 7

If a circuit breaker is open, when should it be reset?

Answer 7

If the affected component is required for safe flight and landing

Question 8

Describe proper operation of the speed brakes with the standby electrical system (hydraulic motor generator) in operation.

Answer 8

Speed brakes may be used provided operation is slow (5 seconds for full movement).

Question 9

When does the “ARM” position of the Emergency Power System switches allow the emergency power system to activate?

Answer 9

If the ESS DC bus voltage drops too low, or a 2.5 G impact

Question 10

The emergency inverter can receive power from what source?

Answer 10

ESS DC bus or the HMG

Question 11

From where do the battery chargers receive their power?

Answer 11

From the respective MAIN AC bus

Question 12

What is the minimum main battery voltage?

Answer 12

22 volts DC

Question 13

Below what voltage would the main batteries require a deep cycle charge?

Answer 13

7 Volts

Question 14

If the batteries actually fell to 20 volts, how long would it take to fully recharge the batteries?

Answer 14

Approximately 90 minutes

Question 15

What 3 items will illuminate the battery switch capsule lights?

Answer 15

1. When L & R batteries are powering the L-R ESSENTIAL DC BUS
2. whenever the AUX HYD PUMP is ON
3. During APU start

Question 16

Whenever the external battery is turned ON, what else will turn on?

Answer 16

Lower rotating beacon

Question 17

Which batteries are activated when the external battery switch is turned ON?

Answer 17

Both main batteries

Question 18

What items are capable of being powered from the battery tie bus?

Answer 18

The auxiliary hydraulic pump, the APU starter and the ESS DC buses

Question 19

What is the general guidance concerning the reset of a tripped circuit breaker?

Answer 19

Reset the affected circuit breaker only if required for continued safe flight and landing

Question 20

Why are the 6 AUTO switches on the EPMP normally selected?

Answer 20

It allows the BPCUs to decide what power sources supplied power to each individual bus

Question 21

What do the percent of power load meters indicate?

Answer 21

The load on that particular bus, expressed as a percentage of the capacity of the source

Question 22

What is the proper sequence to turn on the standby electrical power system (HMG)?

Answer 22

• Standby Electrical Switch - ON
• E Inverter - ON
• TRU - ON

Question 23

Operating limitation for the HMG?

Answer 23

1. Minimum HP RPM is 67%
2. Auto deploy of ground spoilers not authorized
3. Use of TR’s not authorized
4. Use of Speed brakes is permitted, however operation should be slow (5 secs for full range of movement)

Question 24

What actions should the flight crew consider following any electrical power interruptions, with reference to autopilot operations?

Answer 24

1. Check the FGP setting after electrical interruptions
2. Check ALT display to ensure desired altitude is displayed, following changes in the ALT selection in the FGP window
3. Monitor altitude during changes, to ensure autopilot captures and levels off at desired altitude
4. Crews should use standard call outs, crew coordination, and cross-checking techniques to detect any non-selected FPG display changes

Question 25

What is the normal voltage range of the TRU?

Answer 25

24 - 30 volts

Question 26

What is the normal battery voltage range?

Answer 26

22 - 30 volts