DC Electrics

Question 1

A battery discharge condition is indicated by the battery load indicator showing:

• Less than 24 volts
• A flashing negative indication
• A flashing positive indication
• Less than 28 volts

Answer 1

• A flashing negative indication

Question 2

The buses in the DC system which can be manually tied by the crew are:

• The essential buses
• The main feeder buses
• None
• The secondary distribution buses

Answer 2

• The main feeder buses

Question 3

The function of the TRUs is to:

• Convert variable frequency AC to DC
• Convert variable frequency AC to fixed frequency AC
• Provide rectified DC power in the event of a DC generator failure
• Convert DC to variable frequency AC

Answer 3

• Convert variable frequency AC to DC

Question 4

The left TRU supplies the:

• Left secondary bus with 115v fixed frequency AC
• Left secondary bus with 25-29.5 volts DC
• Left secondary bus with 115v variable frequency AC
• Left secondary bus with 26v AC via step down transformers

Answer 4

• Left secondary bus with 25-29.5 volts DC

Question 5

The bus bar protection unit:

• Deselects the AC generators if overloaded, after a 7 second delay
• Protects the batteries from overheating
• Monitors the generators for over voltage conditions
• Protects the batteries and generators from overloads by isolating them

Answer 5

• Protects the batteries and generators from overloads by isolating them

Question 6

When external DC is selected, the aircraft’s electrical system is protected from a faulty external power unit by:

• The BBPU
• An over voltage relay
• The GCU’s
• The BBPU and GCU’s

Answer 6

• An over voltage relay

Question 7

When the BATTERY MASTER switch is selected on:

• The batteries are ready to accept a charge from the Main Feeder buses
• the auxiliary and main batteries energise the secondary buses
• the batteries are connected to the essential buses
• The batteries are connected to the main DC buses

Answer 7

• the batteries are connected to the essential buses

Question 8

When a battery temperature monitor indicates an over temperature condition:

• Air conditioned cool air is directed over the battery
• An audio warning is activated and the QRH should be consulted
• The battery must be manually isolated from the generating system
• A BATT HOT caution light illuminate, and the battery is automatically isolated

Answer 8

• The battery must be manually isolated from the generating system