Question on A320 elec system

[Joaquín]

Hi there,

In the figure of Flight with Batteries Only (FCOM 1.24.10 pp 15 & 16) could anyone tell me what is the box "AC SAT INV" (with a small 9xp on top) between the STAT INV and the AC ESS BUS? It looks like a bus, but it does not have any sense, or does it?

Thanks a lot

[Microburst2002]

It is the AC STATIC INVERTER BUS, supplying those AC equipments needed when flying on bat only. It is suplied by the Static inverter when flying in bat only but it is normally supplied by the AC network.

[philltowns]

I'm a little confused by this. Would it not be the AC ESS BUS which powers what is needed when on batteries only. I dont really understand what the 'AC STAT INV' is for. Any clues!?

[EcamSurprise]

The AC essential bus needs to get power from somewhere right?

Power from the batteries is DC. It needs to be AC..

The AC Static Inverter takes DC power and changes it to AC to power the AC ESS BUS.

A direct quote from the FCOM..
STATIC INVERTER
A static inverter transforms DC power from Battery 1 into one KVA of single-phase 115 V 400 Hz AC power, which is then supplied to part of the AC essential bus. When the aircraft speed is above 50 kt, the inverter is automatically activated, if nothing but the batteries are supplying electrical power to the aircraft, regardless of the BAT 1 and BAT 2 pushbutton positions.
When the aircraft speed is below 50 kt, the inverter is activated, if nothing but the batteries are supplying electrical power to the aircraft, and the BAT 1 and BAT 2 pushbuttons are both on at auto.

Philtowns...if you hold a frozen ATPL as your profile suggest.. surely you would have studied this and be a little less confused?
But then again, maybe it wasn't a question on the Bristol G/S database :E:E:D

[philltowns]

Cheeky! My ATPL's were done in 2005. I'm a bit rusty!

I think my confusion is coming from looking at the FCOM. Between BAT1 and AC ESS BUS, I see the contactor, then a box with STAT INV in, then the AC ESS BUS. However, there's a box coming off between the last two, labelled the AC STAT INV (with the 9XP on top). Do the STAT INV and the AC STAT INV do the same thing, and if so, why are there two?

[rudderrudderrat]

Hi philltowns,
Do the STAT INV and the AC STAT INV do the same thing, and if so, why are there two?
"AC STAT INV 9XP" is a bus bar (part of AC ESS BUS).
It is powered by the STATic INVerter.

[philltowns]

Super, thanks! :)

[Kaban]

AC STAT INV is a bus, feeding:

-Landing gear bindication panel
-Some annunciator lights
-Engine ignition A

Only works in case of flight with batteries only.

Cheers.

[Natstrackalpha]

Hey, listen to the guys - am just a student on the A320 too-
however, AC>TR>DC
>
Given you have 2 main engine gennys AC whose power is turned to DC through the TR (Transformer Rectifier) ok?

>
Now, the power - when your AC gennys . . fail can be obtained from the batteries, although this is decidely limited, but you know that right as you are studying the Electrical system as we speak . . . ? This batt power is DC, so it has to be converted to AC to work AC services.
>
So, the batt(ery) power is DC------DC>Static Invertor>AC
so the power which is DC when fed through the static inverter, becomes AC.

>
AC>DC>TR (note they are all letters)
DC>AC>Static Inverter, ok? Look on the Electrical diagram and you should see this in seconds, its on the electrical ECAM SD.

edited later: - or, in short, as ECAM surprise said.

But then again, maybe it wasn't a question on the Bristol G/S database http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gifhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gif:D - that was funny . . . :)!