nuckolls.bob(at)cox.net
Guest
|
 Posted: Wed Jul 09, 2008 1:55 pm Post subject: Do Alternators fight each other on Z-13/8 |
 |
|
At 08:20 PM 7/9/2008 +0000, you wrote:
| Quote: |
<frank.hinde(at)hp.com>
Alternators are simply voltage generating devices...They aim to put the
regulated voltage on the buss....If the voltage is less than the required
voltage (just over 14V) it will crank up the current to jack up the volts.
If you have two alternators running its almost certain that will not be
exactly the same regulated voltage so the lower voltage alternator will
simply start backing off on the output current. Eventually you will have
one alternator running the entire load and the other will be backed off to
zero amps.
They won't "fight each other" but the non-outputting alternator will
still consume some current in it's field windings so it represents an
additional electrical load.
The SD8 being a permanent magnet device presumably does not consume any
current because it does not have a field winding.
I guee if you have two alternators with exactly the same regulated voltage
I guess it is possible to have each alt taking up the load and then flip
flopping but I would highly doubt that would happen in real life. So no
big deal in my estimation.
Why would you accidently leave them on anyway?..I never switch my SD8 on
because I don't want to risk damaging my Plane power alt by turning it on
and off to test the SD8...So I simply test it at the annual.
|
Good answer Frank. Basically, the alternator with the
highest voltage setting will assume all system loads up
to and including it's capability after which the votlage
sags until the device with the lower voltage setting picks
up the difference.
There is no risk to either system assuming each is cooled
adequately to assume full rated load. This is the principal
behind Z-12 where both alternators are ON during normal
ops with the 20A machine set 0.5 volts low.
Even when you run dual, identical alternators . . . the
higher setpoint device picks up all load until the
bus voltage sags. They don't get into a dueling alternators
mode in any case.
For Z-13/8, the SD-8 is normally used only when the main
alternator is not functional . . . but it doesn't hurt
it if accidently left on. Just for grins, you COULD set
its regulator about 0.5v below the main alternator but
it's not necessary.
Bob . . .
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
