 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
RVdan
Joined: 20 Sep 2012
Posts: 3
|
|
| Back to top |
|
 |
nuckolls.bob(at)aeroelect
Guest
|
 Posted: Thu Sep 20, 2012 11:45 am Post subject: Need for an Alternator switch |
 |
|
At 12:17 PM 9/20/2012, you wrote:
I searched this topic and the more I read the more confusing it
got. I was wondering if this could be quickly summarized.
What did you read that was confusing? Where did you
find advise for not having control of the alternator?
1. Is there a real need for any control of the alternator field line
by a switch (as opposed to being able to pull a CB in an
emergency). Essentially, is there a reason that I need to be able to
turn the alternator on/off routinely?
(yes/no only please)
I'm sorry, you're in the wrong forum . . .
I don't offer un-substantiated, cookie-cutter answers
and I hope others here are similarly disposed to teach
as opposed to dictate.
Legacy design goals for aircraft have cited an ability
for the crew of an aircraft to have control of all sources of
electrical power from the cockpit. See the electrical
systems excerpt from FAR 14 Part 23 here:
http://tinyurl.com/8v4y7e4
and in particular paragraph 23.1351.b.4.ii
2.Is the need safety or reliability related? (yes/no)
When you're on short final to the rocks, your emergency
procedure at some point should call for
DC POWER SWITCHES - OFF. Same thing for in-flight fire.
Breakers are not acceptable switches for this process.
3. If it is safety or reliability related what is/are the
safety/reliability concerns. (Now you get to type away) ' '
I want to eliminate the alternator switch altogether. Not even
control it through a set of poles on the battery switch. I'm hoping
Bob chimes in on this one.
You can help us help you better if you cite the foundations
you've discovered or developed that support the proposed
changes.
What kind of airplane did you take your training
in. Was it not fitted with legacy controls for all
DC power? What was the nature and magnitude of inconvenience
for having to position those switches for the mode of
flight being anticipated?
Are you starting with any of the Z-figures as a foundation?
What changes are you proposing? What advantages are
anticipated by those changes? Are you cognizant of all
the reasons why things are drawn the way they are?
Not trying to be obtuse but you've asked questions for which
the answers have foundation in 100+ years of lessons learned
along with the evolutionary discovery of more elegant
solutions. If you have an alternate design goal, we need
to know what it is before we can assume proper roles as
teachers.
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 |
|
|
|
| Back to top |
|
|
bigginsking
Joined: 25 Sep 2012
Posts: 27
Location: San Diego, California
|
| Posted: Wed Sep 26, 2012 9:42 am Post subject: Re: Need for an Alternator switch |
|
|
I've got something similar to Z-8, with the SD-8 section deleted and a diode maintained emergency battery that feeds the essential bus through a switch labeled "critical"(actually it is a double pole, paralleled for capacity and reliability).
When I say "diode maintained battery" I mean the battery is fed from the main bus, through a fuse rated at 150% of the 40A alternator capacity, then a diode of similar capacity. The essential bus is fed through a second diode at the fuse diode junction just as shown on Z-8 except for the addition of the already mentioned fuse between the main and essential buss.
Z-8 switches the main alternator with the master but it seems redundant to have the main bus switched from the contactor and at the same time switch the field, especially when you consider they are mechanically tied to each other. With Z-8, as it is, you're breaking/making the field circuit twice. Why? Didn't make any sense to me so I deleted the main alternator switch.
I have a 5A pull breaker for the LR-3 regulator. That is the only breaker I have.
If I'm "on short final for the rocks" I just turn off the master and critical switches that's everything including the alternator field.
I didn't know what that switch would add so I deleted it.
As an FYI, I'm also running dual electronic ignition. Those are fed via fuselink directly from each battery. I have no vacuum pump, my instruments are electric, although a GPS and the ADHRS have internal battery backups. I do fly IFR in this plane.
I don't really care if certified aircraft have the alternator switch or not, the question for everything I put in my plane is do I need it? What am I getting?
Bill Judge
N84WJ, RV-8 817 hrs
http://rv-8.blogspot.com
| | - 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 |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
