Today's Message Index:
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1. 08:05 AM - Re: Possible OV condition with Z 16 diagram (Robert L. Nuckolls, III)
2. 11:39 AM - Strobe lamp wiring question ()
3. 11:00 PM - handheld and intercom (Jim and Lucy)
Message 1
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| Subject: | Re: Possible OV condition with Z 16 diagram |
?
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <rnuckolls@aeroelectric.com>
?
At 10:08 PM 7/24/2004 +0200, you wrote:
>--> AeroElectric-List message posted by:
>
>Hi Bob and all,
>
>The completion of our four seater is not far now, and the time will come for
>the first start up.
>We have a Rotax 914 wired as per fig Z 16 with dual battery. Some fellow
>builders have already flown their own projects, and have been aware of a
>possible snag with the OV wiring and the Rotax regulator as well as the
>Schicke GR4 regulator. They have been experiencing alarming OV conditions on
>shutdown.
How do they know there has been an OV condition?
>Scenario :
>According to fig Z 16 the regulator "sense" wire (C wire) is connected to
>the bus through the S700-2-10 master switch. When one opens the master or
>the OV module fires, the sense wire sees zero volt.
>The regulator then throws the full alternator output at the capacitor
>through the wires B and R. The capacitor is rated for 25 volts and could
>suffer from the 60-100 volts.
Have they measured a 60-volt plus event?
>The scenario is quite similar with the Schicke regulator.
Are they turning the switch off during high engine rpm operation?
Those PM alternators don't put out much at idle and the alternator
switch not normally operated at high rpms. This is a situation similar
to that which precipitated the great load-dump investigation a few
months ago. If switches are operated like you would 99.99% of the time
preflighting or parking the airplane, there is little or no risk of the
even happening.
>To prevent this condition one could connect the sense wire (C wire) directly
>to the capacitor, and not to the master switch. Thus the regulator always
>sees a load and no ill effect is produced when the master is opened.
>
>What is your opinion about this variation on the Z 16 theme ? Doable, not
>doable ?
Give it a try. I don't think there's any risk to the hardware
but given that perhaps a hundred plus airplane are flying with
Figure Z-16 wiring, I'm interested in figuring out the details
of the observed event and deducing why it took so long to
surface.
In conversations with Rotax ten years ago I was told that opening
the "C" lead shuts the alternator OFF. Precipitation of a high
voltage event was not mentioned. We need to explore this. Perhaps
something about your regulator is different than the original
regulators supplied with the Rotax.
Bob . . .
---
Message 2
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| Subject: | Strobe lamp wiring question |
--> AeroElectric-List message posted by: <chaztuna@adelphia.net>
Bob & Listers,
What is your opinion of the shielded strobe lamp to power supply wire which was
supplied with my Nova strobe system? This shielded 3 lead wire harness is listed
as 60 degree Centigrade (140 F) rated wire. The number E129931 is imprinted
on the outer casing. Is this wire's temp rating adequate for use in hot climates?
Is there any advantage to replacing this wire with MIL 27500 wire? (I have
both) Is there any practical advantage with regards to shielding, of one of
these wire types as opposed to the other?
Charlie Kuss
RV-8A cockpit wiring & systems
Boca Raton, Fl.
Message 3
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| Subject: | handheld and intercom |
--> AeroElectric-List message posted by: Jim and Lucy <jpollard@mnsi.net>
Looking through the installation manual for a NAT
intercom,It shows the push to talk switch grounds
one of the pins on the intercom which grounds
one of the pins on the radio to put it into
the transmit mode.
If I use a handheld radio in
place of a panel mount radio, do these handhelds
work the same?? Is the airframe ground the same
as the handheld ground to activate the transmitter?
If the handheld was operating off internal batteries
I don't see how it could be.
I have not picked out a handheld radio yet but that
is the way I would like to go.
thanks
Jim Pollard
ch601hds
wireing and plumbing
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