Mauledriver(at)nc.rr.com
Guest
|
 Posted: Mon Sep 02, 2013 8:12 am Post subject: Low voltage indicator with dual alternators |
 |
|
The Z-14, my kitchen sink, and operations with an interconnected dual bus redux:
Bob, you said somewhere below:
| Quote: | "As you have deduced, running them in parallel during normal operations has the potential for obscuring failure of one of the alternators."
|
'duh, yeah...
During my 2nd annual condition inspection on my RV10 I found a fatigued ring terminal on my secondary alternator because I didn't leave enough slack in the 8AWG wire. The magnitude of movement between the hind end of the B&C 20amp pad mounted alternator and the firewall is probably as large as between any other part proximal to the firewall. It was still conducting but probably with high resistance. There were signs of shrink tube melting from heat. It may be the root cause of my charging problems which now includes a dead Odyssey 680 battery and the need to operate with both electrical buses interconnected. The good news is that your very robust Z-14 design just went on functioning at 100% for way too many hours while this guileless pilot flew on wondering what was going on while killing a battery and adding a TCW Intelligent Power Stabilizer.
My first flight after replacing the lead and swapping batteries resulted in everything working as expected. My essential 'kitchen sink' will run 'forever' on one 2 year old PC680 battery. The engine starts effortlessly with the buses interconnected, and both buses have normal voltage indications during normal non-interconnected operations.
Thanks for the help, insight, and the elegant Z-14.
Bill "learning to maintain the plane, step by step" Watson
On 7/8/2013 12:58 PM, Bill Watson wrote:
[quote]--> AeroElectric-List message posted by: Bill Watson <Mauledriver(at)nc.rr.com> (Mauledriver(at)nc.rr.com)
On 7/6/2013 9:31 AM, Robert L. Nuckolls, III wrote:
| Quote: | --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> (nuckolls.bob(at)aeroelectric.com)
| Quote: | I have the same setup and that's how it works. That is, the low voltage light simply monitors the voltage on the bus independent of alternator operation. Given that, I've wondered how a failed alternator would manifest itself.
|
What architecture are we talking about? Z-12 or Z-14?
With independent buses for each alternator, the two
systems are normally operated with the cross-feed OPEN.
Each LV montior will tell the condition of it's respective
bus.
|
It's a Z-14
| Quote: |
| Quote: | - If failure was due to an overvoltage situation, the breaker would pop. Since I normally fly with the 2 buses interconnected
|
Not recommended.
|
I see what you mean.
| Quote: |
| Quote: | I would expect the low voltage lights to remain off perhaps for the remainder of the flight. If one did come on because bus voltage dropped below the threshold, I would expect both to come on more or less simultaneously as long as the buses were interconnected. The only explicit indication of Alt failure would be the popped OV breaker.
|
The design goals for Z-14 were two-fold. (1)
being able to parallel batteries for engine
cranking and (2) being able to share power between
systems in the event of an alternator failure.
As you have deduced, running them in parallel
during normal operations has the potential for
obscuring failure of one of the alternators.
|
My operational goals for the Z-14 included being able to run much of the panel on one battery while still having a fully charged battery for starting. The idea being that I wanted to be able to enter flight plans and even check weather before engine start. That's worked out well. I can connect the buses for starts if needed and that works well as well. However, I normally start with the buses separated because if I go parallel, the voltage drop causes my 3 MDFs to re-boot.
| Quote: |
| Quote: | - Are there other modes of Alternator failure where there would be no explicit indication of failure? I'm thinking that a snapped belt would be an example. If loads and battery condition were such that the interconnected bus voltage stayed above the low volt threshold, there would be no explicit indication. Is that right?
|
Yes. Another reason for running them independently
of each other for normal flight ops. With the crossfeed
closed, you have a Z-12 with dual batteries. Unless
one alternator is configured for stand-by operation by
incorporation of the appropriate regulator, then you
have two alternators in a paralleled mode of operation
controlled by regulators not designed for paralleling
(current management) of the two alternators.
|
I'll be going back to running independent. I know what got me started running with the buses interconnected but I lost track of what this robust configuration is designed to do.
Thanks Bob!
-----
No virus found in this message.
Checked by AVG - www.avg.com
07/08/13
[b]
| | - 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
