Today's Message Index:
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1. 05:39 AM - Re: It's the little things (Glen Matejcek)
2. 10:41 AM - Re: RV-6A load analysis/architecture (Vern Little)
3. 02:32 PM - Re: Starter switch p-lead ground questions (RVBUILDER1)
4. 06:02 PM - Xcxh vcc (Michael Zwijacz)
5. 09:27 PM - Re: Re: Starter switch p-lead ground questions (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: It's the little things |
Howdy-
Might I suggest you contact the shop owner, tell him what you found, and that a
couple thousand people on this list all around the planet are waiting to see
how he handles the situation? We all make mistakes, but hopefully we don't make
others pay for them...
Glen Matejcek
Message 2
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| Subject: | Re: RV-6A load analysis/architecture |
There is nothing fundamentally wrong with any of this. The
recommendation to switch the output of the voltage regulator eliminates
a lot of problems with switching the input/sense side of some regulators
(Bob has a lot of documentation on this problem).
The Wye center point is just like the neutral in your house wiring... it
should always be close to ground potential except when something bad
happens. My guess is the regulator can sense this (similar to a ground
fault detector). Not sure what it does when something goes wrong.
As for the crowbar... yes! It=99s very simple and cheap
insurance. Don=99t depend on an audible warning. The OVP
protection is much faster.
The only issue is keeping the alternator cool when loaded to full
capacity at low airspeeds and taxiing. You should be fine if you pay
attention to cooling, but there=99s not a lot of margin. If you
can, my suggestion of attaching a temperature probe to the alternator
may help=94program the GRT EIS to provide a warning when exceeding
about 150C on the diodes so you can do some load shedding. This applies
to any rating of alternator.
V
From: Jeff B.
Sent: Saturday, August 27, 2011 10:03 PM
Subject: Re: AeroElectric-List: RV-6A load analysis/architecture
Vern & Ken, thanks for the input. I figured 10A or so ought to cover
charging, but after a cold day start that battery might be pretty taxed.
I did forget to consider the lower RPM during taxi and such.
Alternator: here's where I don't understand the present installation.
The present installation has an "Overhauled lightweight 35 Amp
alternator" from Mark Landoll's Electrical Service. It includes a
Transpo F7078 external regulator. The sales documentation (attached)
shows the regulator installed as attached to the alternator. But, the
as-built has the regulator installed behind the instrument panel,
separated from the alternator. The field line appears to be directly
switched. The regulation signal, as stated by the Landoll data sheet as
"the wye junction of the Ford stator is the source of the signal for the
F7078 regulator. At 1200 RPM, the stator magnitude is only 35 mV." I'm
not up to snuff on my motor/generator theory, so I can't visualize what
is happening with this setup. This setup doesn't seem to match what I
see in the Aeroelectric Connection. Is this an optimal way of doing
things, or are there advantages to the ways that Bob describes vs. this
Transpo setup? Will the split between alternator and regulator create
unforeseen issues?
Even if we kept the alternator, I would change the panel mounted B-lead
breaker protection to ANL style near the battery.
We might up the size of the alternator a bit and go with simple external
regulation (generic Ford regulator or such). So, my questions about
operation and potential for problems is mostly to satisfy my desire to
learn.
Second question: We will have a crowbar circuit for OVP, but does anyone
see a problem with relying on the GRT EIS4000 to supply the "low
voltage" warning? The EIS has a low-RPM maskable low voltage alert.
-Jeff-
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Message 3
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| Subject: | Re: Starter switch p-lead ground questions |
Bob
I have two impulse coupled mags on my Lyc 0-290D. That is what was on the engine
when purchased. Do I need the jumper on the G to R termial. I don't have
it on now and it starts fine.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=350875#350875
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CcxcvXcccc
Message 5
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| Subject: | Re: Starter switch p-lead ground questions |
At 04:25 PM 8/28/2011, you wrote:
>
>Bob
> I have two impulse coupled mags on my Lyc 0-290D. That is what
> was on the engine when purchased. Do I need the jumper on the G to
> R termial. I don't have it on now and it starts fine.
The jumper is used to disable a NON-impulse coupled magneto during
cranking. With two I-C mags, you want both mags working to the best
of their ability during cranking so no jumper is called for.
Bob . . .
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