Section 02 - Electrical Flashcards
Where does the 300-amp, 28-volt TRU receive its power from?
Either the LEFT or RIGHT MAIN AC bus, or the HMG
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?
QRH Supplemental Procedures & Data (Section S)
What is indicated by an amber “AC RESET” indication on the EPMP?
An AC bUS fault is indicated
What buses can be powered by the Standby Electrical Power System (HMG)?
ESS DC, and ESS AC (phase A only)
What is the restriction on converter operation with a fan inoperative?
Continued operation for a maximum of 25hrs is permitted, as long as only 1 cooling fan has failed.
What indication and automatic action will occur if a left converter fails?
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.
If a circuit breaker is open, when should it be reset?
If the affected component is required for safe flight and landing
Describe proper operation of the speed brakes with the standby electrical system (hydraulic motor generator) in operation.
Speed brakes may be used provided operation is slow (5 seconds for full movement).
When does the “ARM” position of the Emergency Power System switches allow the emergency power system to activate?
If the ESS DC bus voltage drops too low, or a 2.5 G impact
The emergency inverter can receive power from what source?
ESS DC bus or the HMG
From where do the battery chargers receive their power?
From the respective MAIN AC bus
What is the minimum main battery voltage?
22 volts DC
Below what voltage would the main batteries require a deep cycle charge?
7 Volts
If the batteries actually fell to 20 volts, how long would it take to fully recharge the batteries?
Approximately 90 minutes
What 3 items will illuminate the battery switch capsule lights?
- When L & R batteries are powering the L-R ESSENTIAL DC BUS
- whenever the AUX HYD PUMP is ON
- During APU start
Whenever the external battery is turned ON, what else will turn on?
Lower rotating beacon
Which batteries are activated when the external battery switch is turned ON?
Both main batteries
What items are capable of being powered from the battery tie bus?
The auxiliary hydraulic pump, the APU starter and the ESS DC buses
What is the general guidance concerning the reset of a tripped circuit breaker?
Reset the affected circuit breaker only if required for continued safe flight and landing
Why are the 6 AUTO switches on the EPMP normally selected?
It allows the BPCUs to decide what power sources supplied power to each individual bus
What do the percent of power load meters indicate?
The load on that particular bus, expressed as a percentage of the capacity of the source
What is the proper sequence to turn on the standby electrical power system (HMG)?
- Standby Electrical Switch - ON
- E Inverter - ON
- TRU - ON
Operating limitation for the HMG?
- Minimum HP RPM is 67%
- Auto deploy of ground spoilers not authorized
- Use of TR’s not authorized
- Use of Speed brakes is permitted, however operation should be slow (5 secs for full range of movement)
What actions should the flight crew consider following any electrical power interruptions, with reference to autopilot operations?
- Check the FGP setting after electrical interruptions
- Check ALT display to ensure desired altitude is displayed, following changes in the ALT selection in the FGP window
- Monitor altitude during changes, to ensure autopilot captures and levels off at desired altitude
- Crews should use standard call outs, crew coordination, and cross-checking techniques to detect any non-selected FPG display changes
What is the normal voltage range of the TRU?
24 - 30 volts
What is the normal battery voltage range?
22 - 30 volts
