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nuckolls.bob(at)aeroelect
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 Posted: Fri Jun 05, 2009 6:30 am Post subject: E-bus design goals |
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At 08:30 PM 6/4/2009, you wrote:
| Quote: | Hi Etienne,
As best I can recall from over 10 years ago, I decided I did not want the voltage drop caused by a isolation diode . . .
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Yeah, that bit of physics seems to bug some folks . . .
but more than necessary or useful. Keep in mind that
when the worst happens (alternator quits) the
battery delivers energy at 12.5 down to about 11.0
volts. All our electro-whizzies are designed to
either produce useful performance over this voltage range
else they are NOT suitable for installation in airplanes.
When the e-bus is being powered from the main bus
via the back-feed isolation diode, the main bus
runs at 14.2 to 14.6 volts. A 0.7 to 0.8 volt
drop in the diode depresses the e-bus to
a minimum of 13.4 volts - a value that is about
1.0 volt HIGHER than delivered by a battery alone.
The voltage drop may be reduced by utilization of
a Schottky rectifier . . .
http://en.wikipedia.org/wiki/Schottky_diode
. . . if the builder is willing to
give up the cost and convenience of installation
for the silicon diode bridge rectifier described
in my writings:
http://aeroelectric.com/Pictures/Misc/s401-25.jpg
Several products crafted for the OBAM aircraft
market speak to a design goal for lower voltage
drop . . .
http://aeroelectric.com/Catalog/AEC/9001/IM9001-700A.pdf
http://www.periheliondesign.com/powerschottkydiodes.htm
The latter product offers the lower voltage drop
characteristic of the Schottky junction diode
however, the application schematic shown
in the link above is not the correct implementation
of the e-bus philosophy described in the 'Connection.
See:
http://aeroelectric.com/R12A/AppZ_12A3.pdf
All this makes a mountain out of a mole hill.
When used as illustrated in the Z-figures, the
voltage drop offered by either silicon junction or
Schottky devices has no operational significance
for achieving the original design goals that gave
rise to the e-bus about 15 years ago.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
--------------------------------------- [quote][b]
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bwestfall
Joined: 22 Oct 2008
Posts: 131
Location: Portland, OR
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| Posted: Fri Jun 05, 2009 8:38 am Post subject: E-bus design goals |
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Is it possible to have both the E-Bus switch and the Master ON at the same time? Wouldn’t this power the ebus stuff at full voltage?
-Ben Westfall
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mikef(at)apexconsultingse
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| Posted: Fri Jun 05, 2009 10:08 am Post subject: E-bus design goals |
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In the Z19 (what I did) the Diode between the Main Power bus and the EBus prevents that.
On Fri, Jun 5, 2009 at 10:33 AM, Ben Westfall <rv10(at)sinkrate.com (rv10(at)sinkrate.com)> wrote:
| Quote: |
Is it possible to have both the E-Bus switch and the Master ON at the same time? Wouldn’t this power the ebus stuff at full voltage?
-Ben Westfall
__________ Information from ESET NOD32 Antivirus, version of virus signature database 4134 (20090605) __________
The message was checked by ESET NOD32 Antivirus.
er">http://www.matronics.com/Navigator?AeroElectric-List tp://forums.matronics.com _blank">http://www.matronics.com/contribution
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--
Mike
================================
Mike Fontenot
Apex Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef AT apexconsultingservices DOT com
=======
[quote][b]
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nuckollsr
Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS
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| Posted: Sat Jun 06, 2009 5:14 am Post subject: Re: E-bus design goals |
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There are no risks to electro-whizzies for operating the airplane with the e-bus alternate feed switch ON. However, you need to pre flight test the two power paths for operation. The original operating protocols suggested closing the e-bus alternate feed switch to power up the comm radio to get the ATIS and/or clearance delivery. This presumes, of course that your departure field has such services. If not, then closing this switch momentarily before doing anything else proves availability of this power path. The e-bus alternate feed switch would be off after closing the battery contactor and during engine start.
After engine start, the e-bus should be verified energized via the normal feed path diode thus proving that power path. Re-closing the e-bus alternate feed switch later for the purpose of "getting the e-bus voltage up" offers no risk to the system or equipment. Be sure to add "E-bus alternate feed switch - OFF" to the post-flight check list.
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