PPRuNe Forums - View Single Post - A320 APU start in Emerg Electrical Config
Old 28th Jul 2009, 10:19
  #10 (permalink)  
0-8
 
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You can not charge the batteries in the emergency elec config!

1) The emergency generator will never charge the batteries.

2) Even if you can start the APU you won't be able to get the power to the batteries because of the AC Bus failure

Normal config:
APU -> AC BUS 1(2) -> TR 1(2) -> DC BUS 1(2) -> DC BAT BUS -> Batteries

Emerg Elec Config
As you have no AC BUS 1 or 2 the power can not get to the batteries:
APU -> xxx -> xxx -> xxx -> xxx -> Batteries


Slasher had it right in his first post.

If you've got a generator problem - start the APU.
If you've got a double AC bus problem - do NOT start the APU.


Even the A330 (which has a totally seperate APU battery) does not recommend that you switch on the APU in the Emerg Elec Config.

Why?

Because despite having two working generators (on the engines) you are unable to recover either AC bus. An extra generator (APU) is very unlikely to make any difference.

You have a major electrical problem. Applying large electrical currents to faulty electrical systems is not a good idea! You are already having a bad day; the last thing you need is a further fault or fire.

If your TV went bang you wouldn't just plug it into another socket...
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