Today's Message Index:
----------------------
1. 04:31 AM - Re: Choosing a switch and learn how to wire it (Carlos Trigo)
2. 06:15 AM - Re: Re: Manual Battery Switches. (rd2@evenlink.com)
3. 07:04 AM - Re: Re Standby Regulator SB1B-14 (Dave & Brenda Emond)
4. 07:41 AM - Manual Batt Sw distance (Speedy11@aol.com)
5. 07:42 AM - Re: Re: Manual Battery Switches. (rd2@evenlink.com)
6. 08:27 AM - Re: Re Standby Regulator SB1B-14 (Robert L. Nuckolls, III)
7. 08:41 AM - Re: Manual Batt Sw distance (Bob McCallum)
8. 08:58 AM - Re: Manual Batt Sw distance (Robert L. Nuckolls, III)
9. 09:11 AM - Re: Re Standby Regulator SB1B-14 (Dave & Brenda Emond)
10. 09:33 AM - Ammeter shunt for Van's instrument? (Robert L. Nuckolls, III)
11. 10:33 AM - Re: Re Standby Regulator SB1B-14 (Dave & Brenda Emond)
12. 10:53 AM - Re: Choosing a switch and learn how to wire it (Bill Schlatterer)
13. 11:01 AM - Re: Re Standby Regulator SB1B-14 (Robert L. Nuckolls, III)
14. 11:11 AM - Re: Choosing a switch and learn how to wire it (Bill Schlatterer)
15. 11:23 AM - Re: Re Standby Regulator SB1B-14 (Dave & Brenda Emond)
16. 12:39 PM - Mini-EFIS Panel Considerations ()
17. 01:34 PM - For Jeff Smith "How did you do that?" (Jerry Grimmonpre)
18. 01:47 PM - Re: Manual Batt Sw distance (sportav8r@aol.com)
Message 1
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| Subject: | Re: Choosing a switch and learn how to wire it |
--> AeroElectric-List message posted by: "Carlos Trigo" <trigo@mail.telepac.pt>
> --> AeroElectric-List message posted by: "Bill Schlatterer"
> <billschlatterer@sbcglobal.net>
snip
> I assume this is the GRT unit
Yes it is
> If you go with ON-OFF-ON you will cause a reboot as
> you switch through power sources
Very well observed! I definetely cannot use the On-Off-On switch...
> and actually defeat the purpose of the multiple power source
> availability.
Also well observed. Going the way I inicially planned to, I would not have
the "automatic" feature of 2 alternative power sources.
> If you switch both sources to the EFIS so that both are on at the
> same time, the EFIS will draw off the higher bus.
> Todd says the system will not allow one bus to drain the other.
> Assuming that to be true, you may not really gain anything from the
> On-Off-On set up.
I agree with you
> Can't remember the switch number but there is one that switches
> both power sources to the EFIS independently in a simple On-Off
> mode and then lets the EFIS pick whichever has the higher voltage.
Now I need again some expert help here. Which is that switch?
> Even simpler, I "think" you could accomplish the same thing with a
> diode in each power feed to a simple on/off toggle.
Expert listers, which is the best way to go?
> In my configuration, I have a separate switch for the DUs and AHRS
> but each switch applies two power sources to the unit and lets it do
> the rest.
I would like to have only one switch applying both power sources to both
units.
Thanks very much Bill
Carlos
Message 2
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| Subject: | Re: Manual Battery Switches. |
--> AeroElectric-List message posted by: rd2@evenlink.com
Tx for the feedback, Eric.
Rumen
do not archive
_____________________Original message __________________________
(received from Eric M. Jones; Date: 04:38 PM 12/27/2005
-0500)
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: rd2@evenlink.com
>Eric,
>33783-0VGA is 100 amps continuous, 1000 amps surge @ 12 volt; 50 amp
>continuous, 500 amps surge @ 24 volt; 33783-0VGA - no current data provided
>Just wondering - would these be ok for cranking also? Rumen
Rumen,
That's a definite maybe. I don't know how these specs were designed. But the
connector only has to open under load once, and they use these things on
vehicles routinely. I'd make sure they were silicone greased too.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
(508) 764-2072
"Democracy is the theory that the common people know what they want and
deserve to get it good and hard." -- H. L. Mencken
--
Message 3
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| Subject: | Re: Re Standby Regulator SB1B-14 |
--> AeroElectric-List message posted by: "Dave & Brenda Emond" <d_emond@mweb.co.za>
Hi Bob
I would appreciate if you could help by answering the following.
I have decided to go with your z-12L architecture. Could I use a Cessna type
master, and switch between Main alternator and standby using the alt switch
on this master.
This way if overvoltage warning light came on, I could switch over. If
voltage dropped on the main alternator. The standby would automatically take
up the slack.
Dave Emond
#40159
Message 4
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| Subject: | Manual Batt Sw distance |
--> AeroElectric-List message posted by: Speedy11@aol.com
I have two battery switches, one for the front (I call it the Main) battery
and one for the aft (I call it the Standby) battery. I'm planning a 4AWG (or
maybe 6AWG) cable from the main battery to the manual switch (distance of about
22") with a 200A fuse at the battery end. Then from the manual switch back
to the battery compartment to attach to the starter contactor. At that same
connection to the starter contactor, I would take power to the main bus.
Is 22" too far from the battery to have manual switches?
For the aft standby battery, the manual switch is even farther from the
battery - about six feet of #8 wire.
If the wires (cables) from the battery to the manual switch are fused at the
battery, what is the problem with having the manual switches separated from
the battery location?
If the concern is arching during a crash, it seems to me that as soon as any
arching occured the fuse would blow. What am I missing?
Stan Sutterfield
www.rv-8a.net
Message 5
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| Subject: | Re: Manual Battery Switches. |
--> AeroElectric-List message posted by: rd2@evenlink.com
Good points, Bob, thanks a lot.
Rumen
do not archive
_____________________Original message __________________________
(received from Robert L. Nuckolls, III; Date: 09:33 PM
12/27/2005 -0600)
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<nuckollsr@cox.net>
>
>
>33783-0VGA is 100 amps continuous, 1000 amps surge @ 12 volt; 50 amp
>continuous, 500 amps surge @ 24 volt; 33783-0VGA - no current data provided
>Just wondering - would these be ok for cranking also? Rumen
Again, a good example of what switch ratings mean and
what they often fail to explain. Switches are rated to
do SWITCHING. Their service life is likely to be achieved
if one does not exceed limits while SWITCHING. Keep in
mind that a battery contactor generally SWITCHES relatively
small loads assuming most things are OFF when the master
switch is closed . . . well under 20A.
Now, when you hit the starter button, a starter contactor
does the switching but impresses the starter motor's inrush
currents on all other components in the system including the
battery contactor. The widely used RBM/Stancore/White-Rogers
contactors are rated to SWITCH only 70A yet once the contacts
are closed and stable, they don't mind the 500+ amp inrush
it takes to spin up a starter motor from a healthy battery.
The battery switches under discussion are equally suited
to cranking engines as long as you're not using the battery
switch to CONTROL the starter . . . this is the job of another,
intermittent duty contactor designed for that service.
Bob . . .
--
Message 6
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| Subject: | Re: Re Standby Regulator SB1B-14 |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Z-12 should be wired exactly as shown. Normal operations call
for BOTH alternators ON all the time. Automatic changeover and
notification is taken care of by the standby alternator's regulator.
I recommend a progressive transfer DC PWR MASTER switch for the
battery and primary alternator. I've revised Z12 to reflect this
recommendation by showing the 2-10 switch which mimics the opration
of the Cessna (actually, lots of folks use it) split rocker. The updated
Appendix Z is available at:
http://aeroelectric.com/articles/Rev11/AppZ_R11E.pdf
Revised pages only are:
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z11L.pdf
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z12M.pdf
Bob . . .
At 05:03 PM 12/28/2005 +0200, you wrote:
>--> AeroElectric-List message posted by: "Dave & Brenda Emond"
><d_emond@mweb.co.za>
>
>Hi Bob
>
>I would appreciate if you could help by answering the following.
>
>I have decided to go with your z-12L architecture. Could I use a Cessna type
>master, and switch between Main alternator and standby using the alt switch
>on this master.
>
>This way if overvoltage warning light came on, I could switch over. If
>voltage dropped on the main alternator. The standby would automatically take
>up the slack.
>
>Dave Emond
>#40159
Message 7
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| Subject: | Re: Manual Batt Sw distance |
--> AeroElectric-List message posted by: "Bob McCallum" <robert.mccallum2@sympatico.ca>
Stan;
What I believe you are missing is, in a crash situation with a 200Amp fuse,
as you suggest, there is no guarantee that it would "blow" under "arcing"
conditions. It is quite possible for a fault to occur on your main battery
cable which would arc away happily at 100 or 150 amps, melting sheet
aluminium, and your 200Amp fuse would dutifully supply this fault with all
the energy it requested. In the meantime your ruptured fuel tank has
provided the potential for a complete conflagration. If the fault were truly
a "hard" ground with minimal resistance you're correct that the fuse will
probably open, but what about the "partial" ground having a resistance of
say only 1/10th of an ohm? Ohms law says this fault will draw 120 amps, far
below the value to open your fuse. I would consider 1/10th ohm to be a
pretty good "short" yet it wouldn't open your fuse. Also if you're depending
on the "arc" to open a fuse, will that arc, in the meantime, have ignited
the spilled fuel anyway??? Something to think about. Best to have everything
electrically "dead" BEFORE the wire grounds out or the fuel spills hence the
master relay or switch as close as possible to the battery to minimize what
remains "live".
Bob McC
----- Original Message -----
From: <Speedy11@aol.com>
Subject: AeroElectric-List: Manual Batt Sw distance
> --> AeroElectric-List message posted by: Speedy11@aol.com
>
> I have two battery switches, one for the front (I call it the Main)
battery
> and one for the aft (I call it the Standby) battery. I'm planning a 4AWG
(or
> maybe 6AWG) cable from the main battery to the manual switch (distance of
about
> 22") with a 200A fuse at the battery end. Then from the manual switch
back
> to the battery compartment to attach to the starter contactor. At that
same
> connection to the starter contactor, I would take power to the main bus.
> Is 22" too far from the battery to have manual switches?
> For the aft standby battery, the manual switch is even farther from the
> battery - about six feet of #8 wire.
> If the wires (cables) from the battery to the manual switch are fused at
the
> battery, what is the problem with having the manual switches separated
from
> the battery location?
> If the concern is arching during a crash, it seems to me that as soon as
any
> arching occured the fuse would blow. What am I missing?
> Stan Sutterfield
> www.rv-8a.net
>
>
Message 8
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| Subject: | Re: Manual Batt Sw distance |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:40 AM 12/28/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: Speedy11@aol.com
>
>I have two battery switches, one for the front (I call it the Main) battery
>and one for the aft (I call it the Standby) battery. I'm planning a 4AWG (or
>maybe 6AWG) cable from the main battery to the manual switch (distance of
>about
>22") with a 200A fuse at the battery end. Then from the manual switch back
>to the battery compartment to attach to the starter contactor. At that same
>connection to the starter contactor, I would take power to the main bus.
>Is 22" too far from the battery to have manual switches?
>For the aft standby battery, the manual switch is even farther from the
>battery - about six feet of #8 wire.
>If the wires (cables) from the battery to the manual switch are fused at the
>battery, what is the problem with having the manual switches separated from
>the battery location?
>If the concern is arching during a crash, it seems to me that as soon as any
>arching occured the fuse would blow. What am I missing?
The design goals for aircraft battery control have
been to provide positive disconnect of the battery
as close as practical to the battery. For all but
a few production aircraft, these goals suggest the
use of REMOTE switches (contactors) in lieu of
LOCAL switches because the battery(ies) are too
far out of reach of the pilot to make manual switching
practical.
Large limiters (ANL style) are not even close to
the operating speed of what we call "fuses". See
http://www.aeroelectric.com/Mfgr_Data/Fuses_and_Current_Limiters/Bussman/anl.pdf
These are intended to clear hard faults during system
operation, not limit potential energy available for
crash safety. The battery "fuse" is not a substitute
for local disconnection in case of imminent contact
with the rocks or for being able to make 99.9% of
wiring "cold" with smoke in the cockpit.
You may certainly wire your airplane any way you
wish but be sure your understand the ramifications
for substituting alternative philosophies.
Why the push for manual switches? The battery contactor
weighs 13 oz. A battery switch will be about 5-6 oz and
if you need to add a remote control cable, installed
weight will be on the same order as the battery contactor.
The battery contactor has been with us for a very
long time and has proven to be one of the least problematic
pieces of equipment with respect to cost of ownership.
Bob . . .
Message 9
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| Subject: | Re: Re Standby Regulator SB1B-14 |
--> AeroElectric-List message posted by: "Dave & Brenda Emond" <d_emond@mweb.co.za>
Thanks Bob
*DO NOT ARCHIVE*
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Re Standby Regulator SB1B-14
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
>
> Z-12 should be wired exactly as shown. Normal operations call
> for BOTH alternators ON all the time. Automatic changeover and
> notification is taken care of by the standby alternator's regulator.
>
> I recommend a progressive transfer DC PWR MASTER switch for the
> battery and primary alternator. I've revised Z12 to reflect this
> recommendation by showing the 2-10 switch which mimics the opration
> of the Cessna (actually, lots of folks use it) split rocker. The updated
> Appendix Z is available at:
>
> http://aeroelectric.com/articles/Rev11/AppZ_R11E.pdf
>
> Revised pages only are:
>
> http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z11L.pdf
>
> http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z12M.pdf
>
> Bob . . .
>
> At 05:03 PM 12/28/2005 +0200, you wrote:
>
>>--> AeroElectric-List message posted by: "Dave & Brenda Emond"
>><d_emond@mweb.co.za>
>>
>>Hi Bob
>>
>>I would appreciate if you could help by answering the following.
>>
>>I have decided to go with your z-12L architecture. Could I use a Cessna
>>type
>>master, and switch between Main alternator and standby using the alt
>>switch
>>on this master.
>>
>>This way if overvoltage warning light came on, I could switch over. If
>>voltage dropped on the main alternator. The standby would automatically
>>take
>>up the slack.
>>
>>Dave Emond
>>#40159
>
>
>
Message 10
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| Subject: | Ammeter shunt for Van's instrument? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
If I have a 60 amp alternator and use your 60 amp shunt with the standard
Van's 40 amp gauge does a full deflection on the gauge indicate 60
amps? In this senario I could re-mark the indicator to +/- 60 amps and all
is well?
Van's instrument is not a "standard" 50mv full scale device.
It's a 40mv/40A device. This means the shunt is a 50A shunt
in the 50mv world but re-rated to fit his 40 Mv instrument. So, to
make Van's instrument a 60A full scale device, you'll need a
shunt that's 40mv/60A which translates to a 75A shunt in the
50 mV world. I don't have 75A shunts, B&C might have them. I
can probably re-calibrate one of our shunts for your needs
if you can't find one off-the-shelf.
Bob . . .
Message 11
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| Subject: | Re: Re Standby Regulator SB1B-14 |
--> AeroElectric-List message posted by: "Dave & Brenda Emond" <d_emond@mweb.co.za>
Bob
Can you please clarify for me. Assuming my RV is wired exaclty like the
Z-12M schematics.
What event/s would cause me to have to switch the 2-10 to battery, from the
batt/Alt position???
Dave
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Re Standby Regulator SB1B-14
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
>
> Z-12 should be wired exactly as shown. Normal operations call
> for BOTH alternators ON all the time. Automatic changeover and
> notification is taken care of by the standby alternator's regulator.
>
> I recommend a progressive transfer DC PWR MASTER switch for the
> battery and primary alternator. I've revised Z12 to reflect this
> recommendation by showing the 2-10 switch which mimics the opration
> of the Cessna (actually, lots of folks use it) split rocker. The updated
> Appendix Z is available at:
>
> http://aeroelectric.com/articles/Rev11/AppZ_R11E.pdf
>
> Revised pages only are:
>
> http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z11L.pdf
>
> http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z12M.pdf
>
> Bob . . .
>
> At 05:03 PM 12/28/2005 +0200, you wrote:
>
>>--> AeroElectric-List message posted by: "Dave & Brenda Emond"
>><d_emond@mweb.co.za>
>>
>>Hi Bob
>>
>>I would appreciate if you could help by answering the following.
>>
>>I have decided to go with your z-12L architecture. Could I use a Cessna
>>type
>>master, and switch between Main alternator and standby using the alt
>>switch
>>on this master.
>>
>>This way if overvoltage warning light came on, I could switch over. If
>>voltage dropped on the main alternator. The standby would automatically
>>take
>>up the slack.
>>
>>Dave Emond
>>#40159
>
>
>
Message 12
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| Subject: | Choosing a switch and learn how to wire it |
--> AeroElectric-List message posted by: "Bill Schlatterer" <billschlatterer@sbcglobal.net>
Carlos, I think a SA 816 $2.00 from Steinair will work for what you want to
do. http://www.steinair.com/switches.htm Connecting the center and bottom
on one side for one power circuit to the DU and AHRS and same on other side
for the other power circuit should bring up both at the same time and allow
the GRT system to pick. Assume you are running the EIS direct to main bus.
Note, this does impose a single point of failure on the switch itself which
could be offset in several ways if you think that's really an issue. I have
the dual display system and will run a separate switch to each DU, AHRS, and
power each from the e-bus and the backup EFIS battery per Z-35.
Hope this helps but realize this is mew to me as well so it may be less than
optimum if you really knew what you were doing :-)
Good Luck
Bill S
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Carlos
Trigo
Subject: Re: AeroElectric-List: Choosing a switch and learn how to wire
it
--> AeroElectric-List message posted by: "Carlos Trigo"
<trigo@mail.telepac.pt>
> --> AeroElectric-List message posted by: "Bill Schlatterer"
> <billschlatterer@sbcglobal.net>
snip
> I assume this is the GRT unit
Yes it is
> If you go with ON-OFF-ON you will cause a reboot as
> you switch through power sources
Very well observed! I definetely cannot use the On-Off-On switch...
> and actually defeat the purpose of the multiple power source
> availability.
Also well observed. Going the way I inicially planned to, I would not have
the "automatic" feature of 2 alternative power sources.
> If you switch both sources to the EFIS so that both are on at the
> same time, the EFIS will draw off the higher bus.
> Todd says the system will not allow one bus to drain the other.
> Assuming that to be true, you may not really gain anything from the
> On-Off-On set up.
I agree with you
> Can't remember the switch number but there is one that switches
> both power sources to the EFIS independently in a simple On-Off
> mode and then lets the EFIS pick whichever has the higher voltage.
Now I need again some expert help here. Which is that switch?
> Even simpler, I "think" you could accomplish the same thing with a
> diode in each power feed to a simple on/off toggle.
Expert listers, which is the best way to go?
> In my configuration, I have a separate switch for the DUs and AHRS
> but each switch applies two power sources to the unit and lets it do
> the rest.
I would like to have only one switch applying both power sources to both
units.
Thanks very much Bill
Carlos
Message 13
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| Subject: | Re: Re Standby Regulator SB1B-14 |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:31 PM 12/28/2005 +0200, you wrote:
>--> AeroElectric-List message posted by: "Dave & Brenda Emond"
><d_emond@mweb.co.za>
>
>Bob
>
>Can you please clarify for me. Assuming my RV is wired exaclty like the
>Z-12M schematics.
>
>What event/s would cause me to have to switch the 2-10 to battery, from the
>batt/Alt position???
If the main alternator has failed . . . you have no way to
deduce exactly why. Procedure is to shut it OFF after the
AUX ALT LOADED warning light comes on.
Also, if you wish to do ground maintenance on the airplane
without the engine running . . . you don't want the field
circuit of the alternator to draw battery current for no
good purpose. You can conduct maintenance in the BAT only
position and relieve the battery of carrying field loads
for a non-rotating alternator.
Bob . . .
Message 14
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| Subject: | Choosing a switch and learn how to wire it |
--> AeroElectric-List message posted by: "Bill Schlatterer" <billschlatterer@sbcglobal.net>
Carlos, minor issue on the switch diagram attached in the other reply.
Assuming you want up to be on, it should be wired center and top and not
center and bottom. Sorry for the confusion. See attached diagram.
Bill S
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Carlos
Trigo
Subject: Re: AeroElectric-List: Choosing a switch and learn how to wire
it
--> AeroElectric-List message posted by: "Carlos Trigo"
<trigo@mail.telepac.pt>
> --> AeroElectric-List message posted by: "Bill Schlatterer"
> <billschlatterer@sbcglobal.net>
snip
> I assume this is the GRT unit
Yes it is
> If you go with ON-OFF-ON you will cause a reboot as
> you switch through power sources
Very well observed! I definetely cannot use the On-Off-On switch...
> and actually defeat the purpose of the multiple power source
> availability.
Also well observed. Going the way I inicially planned to, I would not have
the "automatic" feature of 2 alternative power sources.
> If you switch both sources to the EFIS so that both are on at the
> same time, the EFIS will draw off the higher bus.
> Todd says the system will not allow one bus to drain the other.
> Assuming that to be true, you may not really gain anything from the
> On-Off-On set up.
I agree with you
> Can't remember the switch number but there is one that switches
> both power sources to the EFIS independently in a simple On-Off
> mode and then lets the EFIS pick whichever has the higher voltage.
Now I need again some expert help here. Which is that switch?
> Even simpler, I "think" you could accomplish the same thing with a
> diode in each power feed to a simple on/off toggle.
Expert listers, which is the best way to go?
> In my configuration, I have a separate switch for the DUs and AHRS
> but each switch applies two power sources to the unit and lets it do
> the rest.
I would like to have only one switch applying both power sources to both
units.
Thanks very much Bill
Carlos
Message 15
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| Subject: | Re: Re Standby Regulator SB1B-14 |
--> AeroElectric-List message posted by: "Dave & Brenda Emond" <d_emond@mweb.co.za>
Thanks Bob
Your patience and explanation is appreciated.
Regards
Dave
*DO NOT ARCHIVE*
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Re Standby Regulator SB1B-14
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
>
> At 08:31 PM 12/28/2005 +0200, you wrote:
>
>>--> AeroElectric-List message posted by: "Dave & Brenda Emond"
>><d_emond@mweb.co.za>
>>
>>Bob
>>
>>Can you please clarify for me. Assuming my RV is wired exaclty like the
>>Z-12M schematics.
>>
>>What event/s would cause me to have to switch the 2-10 to battery, from
>>the
>>batt/Alt position???
>
> If the main alternator has failed . . . you have no way to
> deduce exactly why. Procedure is to shut it OFF after the
> AUX ALT LOADED warning light comes on.
>
> Also, if you wish to do ground maintenance on the airplane
> without the engine running . . . you don't want the field
> circuit of the alternator to draw battery current for no
> good purpose. You can conduct maintenance in the BAT only
> position and relieve the battery of carrying field loads
> for a non-rotating alternator.
>
> Bob . . .
>
>
>
Message 16
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| Subject: | Mini-EFIS Panel Considerations |
INNOCENT GLOBAL 0.0683 1.0000 -1.5857
--> AeroElectric-List message posted by: <bakerocb@cox.net>
Responding to an Avionics-List message previously posted by: "John
Rippengal" <j.rippengal@cytanet.com.cy>
12/28/2005
Hello John, Thanks for your input. By pursuing this issue in some detail I
am trying to avoid the circumstance where a builder discovers too late that
he has created an installation that is a costly nuisance every two years at
IFR cert time. Just "betting on the come" doesn't appeal to me and I assume
that there are other builders that may feel the same way.
<<1) You wrote: "If you have normal pitot and static ports then normal test
equipment can be connected to those ports on the aircraft.">>
The pitot tube and its plumbing should not play a role in the static system
check unless there is a defect inside the airspeed indicator that allows a
leak through between the pitot pressure chamber and the static pressure
chamber in that instrument.
<<2) You wrote: "In anycase the 'on aircraft' test is much preferable since
it checks for leaks and stoppages in the pipework to the pitot/static
system."
The 'on aircraft test' is not just preferable, it is mandatory. See CFR 14
Sec. 91.217 (b) "Unless, as installed, that equipment was tested and
calibrated.....skip....." and CFR 14 Appendix E to Part 43 (c) "....skip...
to ensure that the altitude reporting equipment, altimeters, and ATC
transponders perform their intended functions as installed in the aircraft."
I agree that by far the best circumstance is if the technician agrees to
start the test on plane, has compatible test equipment and encounters no
problems during all phases of the test. But what if after starting the
testing he gets some indeterminate results and can't decide whether it is
the installation, the encoder, or the altimeter that is causing the problem?
The result can be some costly trouble shooting. Whereas if the altimeter and
encoder had been chamber tested by a bench technician prior to the on plane
testing then those two items are eliminated as the source of any problems.
OC
<<If you have normal pitot and static ports then normal test equipment can
be connected to those ports on the aircraft. The test equipment I have seen
generally has 'plug in' adapters to suit. Even though the EFIS is digital
there will be an analogue pressure sensor for both alt (static) and airspeed
(pitot) so you will have to know how to get at the adjustment for those two
items if they need correcting.
You will just have to forget about taking the equipment into the shop. In
anycase the 'on aircraft' test is much preferable since it checks for leaks
and stoppages in the pipework to the pitot/static system.
In Europe I believe, but can't be sure, it is obligatory to do the test on
the aircraft right from the pitot/static ports otherwise you are just
testing the instruments not the system. John Rippengal>>
Message 17
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| Subject: | For Jeff Smith "How did you do that?" |
--> AeroElectric-List message posted by: "Jerry Grimmonpre" <jerry@mc.net>
Jeff ...
How did you display your very fine electrical circuit on Excel? I don't
know of any circuit programs and this one seems to do the job nicely. It
would be great if you could share your knowledge with the entire
aeroelectric list. Your supporting documentation is a sample for us all ...
I've not seen anything like that around here.
Thanks for any help ...
Jerry Grimmonpre'
RV8A electrical
Message 18
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| Subject: | Re: Manual Batt Sw distance |
--> AeroElectric-List message posted by: sportav8r@aol.com
Looking at the ANL data Bob N. provided in his link, it seems there is no prtactical
way to fuse-protect a battery cable, in lieu of a battery contactor, and
have said fuse pass starter current while still providing rapid hard-fault protection.
Too much possibility exists of post-crash arcing and fire when a fuse
is substituted for the battery contactor. This is just the sort of analysis
I was hoping for when I mentioned George's contactor-free wiring proposal last
week. Shedding the weight of the battery contactor would have been nice, but
I guess it presents unacceptable risk. The only other work-around might be
a cable-activated battery disconnect switch, and I'll wager it has nearly the
same all-up weight as the contactor it was meant to replace.
The current winner in my deliberations for a lightweight redundant RV electrical
system is Z-13/8 with the alternator battery lead run straight to the Sky-tec
solenoid terminal, all wired where practical with Eric's FatWire, and the smallest
workable Odyssey battery. It seems to have the best of the best for my
purposes (light weight, all-electric IFR)
-Stormy
-----Original Message-----
From: Bob McCallum <robert.mccallum2@sympatico.ca>
Subject: Re: AeroElectric-List: Manual Batt Sw distance
--> AeroElectric-List message posted by: "Bob McCallum" <robert.mccallum2@sympatico.ca>
Stan;
What I believe you are missing is, in a crash situation with a 200Amp fuse,
as you suggest, there is no guarantee that it would "blow" under "arcing"
conditions. It is quite possible for a fault to occur on your main battery
cable which would arc away happily at 100 or 150 amps, melting sheet
aluminium, and your 200Amp fuse would dutifully supply this fault with all
the energy it requested. In the meantime your ruptured fuel tank has
provided the potential for a complete conflagration. If the fault were truly
a "hard" ground with minimal resistance you're correct that the fuse will
probably open, but what about the "partial" ground having a resistance of
say only 1/10th of an ohm? Ohms law says this fault will draw 120 amps, far
below the value to open your fuse. I would consider 1/10th ohm to be a
pretty good "short" yet it wouldn't open your fuse. Also if you're depending
on the "arc" to open a fuse, will that arc, in the meantime, have ignited
the spilled fuel anyway??? Something to think about. Best to have everything
electrically "dead" BEFORE the wire grounds out or the fuel spills hence the
master relay or switch as close as possible to the battery to minimize what
remains "live".
Bob McC
----- Original Message -----
From: <Speedy11@aol.com>
Subject: AeroElectric-List: Manual Batt Sw distance
> --> AeroElectric-List message posted by: Speedy11@aol.com
>
> I have two battery switches, one for the front (I call it the Main)
battery
> and one for the aft (I call it the Standby) battery. I'm planning a 4AWG
(or
> maybe 6AWG) cable from the main battery to the manual switch (distance of
about
> 22") with a 200A fuse at the battery end. Then from the manual switch
back
> to the battery compartment to attach to the starter contactor. At that
same
> connection to the starter contactor, I would take power to the main bus.
> Is 22" too far from the battery to have manual switches?
> For the aft standby battery, the manual switch is even farther from the
> battery - about six feet of #8 wire.
> If the wires (cables) from the battery to the manual switch are fused at
the
> battery, what is the problem with having the manual switches separated
from
> the battery location?
> If the concern is arching during a crash, it seems to me that as soon as
any
> arching occured the fuse would blow. What am I missing?
> Stan Sutterfield
> www.rv-8a.net
>
>
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