Today's Message Index:
----------------------
1. 08:45 AM - GPS RG142 to regular BNC ? (GTH)
2. 09:46 AM - Re: Re: Another Alternator Question (Robert L. Nuckolls, III)
3. 09:54 AM - Re: Re: Fuse Blocks (Robert L. Nuckolls, III)
4. 10:09 AM - Re: Analog electric clock with a relay circuit for battery capacity test (Robert L. Nuckolls, III)
5. 10:13 AM - Re: Alternators - To Fuse or not to fuse - That IS the question (Robert L. Nuckolls, III)
6. 10:19 AM - Re: Alternators - To Fuse or not to fuse - That IS the question (Robert L. Nuckolls, III)
7. 10:20 AM - Re: Grounding RV (Robert L. Nuckolls, III)
8. 10:30 AM - Re: Re: Alternators - To Fuse or not to fuse - That IS the question (Robert L. Nuckolls, III)
9. 10:37 AM - Re: GPS RG142 to regular BNC ? (Robert L. Nuckolls, III)
10. 11:06 AM - Alternator Question - Redux (kearney)
11. 11:09 AM - A treasure trove of data . . . (Robert L. Nuckolls, III)
12. 11:37 AM - Re: Alternator Question - Redux (don van santen)
13. 12:17 PM - Re: Alternator Question - Redux (Robert L. Nuckolls, III)
14. 07:09 PM - Re: Alternator Question - Redux (user9253)
Message 1
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| Subject: | GPS RG142 to regular BNC ? |
Hi all,
Anybody has a way to cleanly connect a thin RG142 GPS antenna coax to a
regular crimp BNC (with regular crimp tool) for a Garmin GPS ?
I know I did that many years ago, but am unable to remember how I proceeded.
Any hint appreciated,
Thank you,
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
Message 2
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| Subject: | Re: Another Alternator Question |
At 09:02 PM 8/10/2017, you wrote:
>
>Bob / Joe
>
>Thank you for the info it is most helpful. Given that an alternator
>will continue to function even if the battery goes offline, some of
>my redundancy concerns have been addressed.
>
>Based on my application (EFI/EI) the Z-12 dual alternator / single
>battery architecture looks most appropriate.
>
>I have been reviewing each of the various "Z" diagrams trying to
>understand the logic behind each and how it would operate / meet my needs.
>
>I like the Z12 with dual alternators would provide (*I think*) the
>best redundancy in the event of a failure of one of the electrical
>system components.
Keep in mind that Z12 has been in existence for decades
and the failure modes pretty well sifted both in the
OBAM and TC aviation communities on what must now be
thousands of aircraft.
>The only changes to the Z12 I might consider making would be
>
>1. To move the back up alternator field connecton to the endurance
>bus. My rational for this is that a failure of of the DPDT MASTER
>Switch would take
>the main alternator offline perhaps before the backup could energize.
???? milliseconds is too long ???
> If that happened, there would be no way to energize the backup
> alternator field.
Why does the bus voltage dissapear when the
main alternator quits?
> If normal ops had the E-Bus Alternate switch always closed, the
> backup alternator would be energized automatically from the battery
> via the EBUS.
Not recommended. If you want to simplify Z12, eliminate the
endurance bus. The notion behind the endurance bus is to
(1) provide multiple power pathways to equipment needed
for comfortable continuation of flight to airport of
intended destination while (2) minimizing loads on a
limited energy source. The 20+ amps capability of the
standby alternator should alleviate all concerns for
energy limitations . . . conservation goals of the
e-bus are, therefore, moot.
>2. I would eliminate the always hot bus (I wouldn't use it) and put
>all my engine EFI/EI circuits and essential avionics on the
>endurance bus. All other avionics etc would be on the main bus. Some
>of the EFI/EI components are not switched.
Not recommended. If you've got smoke in the cockpit,
you'd like to take the electrical system max-cold
without killing the engine. Electrically dependent
engines are best powered directly from the battery
bus via their own control switches.
>3. Eliminate the alternator loadmeters & hall sensor. I believe the
>EFIS screens will provide current info.
ALL ammeters of ANY form are not flight instruments.
They serve diagnostic purposes for ground maintenance.
If you've done a proper load analysis, then you KNOW
that the alternator(s) are not overloaded in any
flight condition described in your Plan-B as dictated
by FMEA. Hence, anything the ammeters have to say
is of no value for managing the outcome of a flight.
If I were building the simplest possible a/c with
solid failure tolerance, there would be no ammeters
or voltmeters . . . only the active notification of
low voltage. In the case of Z12, the only time you
would see a low volts warning in flight is if the
aux alternator were overloaded whereupon you reduce
loads to turn out the light . . . and truck on.
>4. Eliminate the MAIN VOLTS WARN light. In this case the EFIS should
>provide bus voltage info.
Just how you get ACTIVE NOTIFICATION of low voltage
is optional as long as you have it.
>I would also forgo use of the Vertical Power VP-X (as originally
>planned) as it wouldn't be adding a lot of value above and beyond
>using circuit breakers.
Agreed.
Bob . . .
Message 3
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At 09:34 AM 8/11/2017, you wrote:
>
>Le 10/08/2017 =E0 21:50, user9253 a =E9crit :
>>
>>Here you go Gilles, a picture of the rear of the fuse block.
>
>Thank you Joe, you gave me ideas !
>To everybody, how about installing ANL current limiters on a PCB ?
>Along with the ATO fuses, of course.
If you're building a custom power distribution
center, consider the miniature ANL current
limiters like these . . . much smaller
and readily available.
http://tinyurl.com/y9427ggp
Bob . . .
Message 4
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| Subject: | Re: Analog electric clock with a relay circuit for |
battery capacity test
At 06:21 PM 8/11/2017, you wrote:
>This looks pretty fancy for the price. I have a 20% coupon so it comes to $55.
>
><https://www.harborfreight.com/digital-automotive-battery-analyzer-66892.html>https://www.harborfreight.com/digital-automotive-battery-analyzer-66892.html
>
> * Checks voltage, cold cranking amps (CCA), resistance and
> overall battery condition
> * Continuous testing will not damage battery
> * Uses car battery for power, no extra internal batteries needed
>
>Does the list think this will do the job?
This doesn't measure load carrying ability of
the battery. It computes it based on some measurements
of internal impedance and some assumptions
about temperatures.
Walmart has similar gizmos they use to sell
batteries to customers that just came in
for an oil change.
If you want to test the battery, get one of
these.
http://tinyurl.com/yag4529y
Bob . . .
Message 5
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| Subject: | Re: Alternators - To Fuse or not to fuse - That IS |
the question
At 11:41 AM 8/12/2017, you wrote:
>
>Bib et Al
>
>I have been reading with interest your monographs on fuses and
>circuit breakers. I had always thought that CBs were "modern" and
>fuses were "old school".
>
>So this brings me to an alternator wiring question. Keep in mind
>this is based on the Z12 architecture with an electrically dependent
>engine - EFI/EI.
>
>The questions is: why would I use a CB on the primary and backup
>alternator field circuits?
because the voltage regulators shown feature
crowbar ov protection that needs an upstream
breaker to allow resetting in case of a nuisance
trip . . . rare.
>My rational for thing this is, if the alternator field circuit pops,
>something is wrong, likely with the alternator. With the Z12
>architecture, the backup alternator should immediately come on line
>and keep me, the electro-goodies and the engine happy. Why would I
>ever want to push that breaker back in?.
>
>If the backup alternator field CB then also pops, I would then think
>that something is very seriously amiss. Again, why would I ever want
>to reset that breaker.
>
>In theory I would still have the battery to get me *somewhere*
>safely albeit with urgency.
>
>Inquiring minds need to know.
It's an artifact of the crowbar ov protection system.
If you have a relay-style ov protection module
then an ov condition does NOT trip the breaker . . .
you could use the fuse for field supply 'cause
yes . . . if it pops there is something seriously
wrong. And with Z-12, it's no big deal.
Bob . . .
Message 6
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| Subject: | Re: Alternators - To Fuse or not to fuse - That IS |
the question
At 12:08 PM 8/12/2017, you wrote:
>The conundrum lies in your assumptions. You are assuming that if the
>field circuit breaker pops something must be wrong with the
>alternator system. Not necessarily the case. I'll leave it to others
>with more understanding of such things to elaborate.
B&C regulators are fitted with crowbar ov protection
that deliberately opens the field supply breaker. When
running TWO alternators, it would normally be possible
for ONE alternator to go into ov runaway and trip
both systems . . .
EXCEPT . . .
B&C controller ov systems watch the field voltage
of their respective alternator. If an ov condition
is detected, the field voltage on the failed system
is high . . . the working system's field voltage
is low if not zero. The ov system on the working
alternator is prevented from operating thus leaving
the working system on line.
I think I offered the first selective trip ov protection
system to Cessna waaayyy back when we were asked
to propose a paralleling alternator controller for
the Crusader. Got beat out by ElectroDelta on that
project. I don't recall if their offering included
selective trip . . . it might have been in
Cessna's procurement specification.
Bob . . .
Message 7
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| Subject: | Re: Grounding RV |
At 04:20 PM 8/13/2017, you wrote:
>
>My RV-6A operated 2 plus years with a Subaru and my forest of tabs
>bolted to the stainless firewall with the two thru bolts and nuts
>inside. I have two grounds to the engine from the bolt head and one
>to each of dual oddessy bats. Had another ground on the panel side
>of the glove box attached with metal screws and a #8 wire ground
>from there to the firewall forest.
>
>Am now going to dual EFII on a Lycoming and it has been recommended
>to isolate the glove box ground, leave the 8 wire to firewall ground
>AND to isolate firewall ground and a #8 wire to inside post from
>battery to avoid any ground loops.
>
>Do both changes have merit, or just isolate the glove box
>ground? Also have wing lights grounded by lamps.
Totally unnecessary . . .
Bob . . .
Message 8
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| Subject: | Re: Alternators - To Fuse or not to fuse - That |
IS the question
At 10:00 AM 8/13/2017, you wrote:
>
>Charlie
>
>Your comment on the OV nuisance trip is interesting. How does one
>tell if the OV was a temporary, non-threatening excursion or if it
>is the result of something serious? Resetting the breaker seems risky.
If there's a real trip of the ov protection system
then resetting one time does not represent a big
risk . . . the ov excursion is well under DO160
limits.
>Dave's comment about being able to isolate the field field when
>ship's power is on without the engine makes sense. In that case I
>wounder if a switch and a fuse would be better. Pulling breakers
>seems a bit kludgy.
The z-figures have offered TWO approaches to dC
POWER master switches.
One with the three position master where mid position
is battery only, up position is battery+altenrator
Emacs!
In this case, battery only ops are easily
established with just the switch.
In the past, we've shown that DC PWR MASTER
could be a simple DPST toggle that brings
battery and alternator on together. In
this case, having a field breaker rather
than fuse made it possible to set up
battery only maintenance ops on the ground.
OF course, if the ship was fitted with crowbar
ov protection, then the breaker was already
in place.
Bob . . .
Message 9
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| Subject: | Re: GPS RG142 to regular BNC ? |
At 10:43 AM 8/14/2017, you wrote:
>
>Hi all,
>
>Anybody has a way to cleanly connect a thin RG142 GPS antenna coax
>to a regular crimp BNC (with regular crimp tool) for a Garmin GPS ?
>
>I know I did that many years ago, but am unable to remember how I proceeded.
>
>Any hint appreciated,
>
>Thank you,
RG-141. RG-142 and RG-400 apply with the same
tool on the same connectors
Bob . . .
Message 10
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| Subject: | Alternator Question - Redux |
Bob
Thank you for your comments and explanations they were most helpful.
I have started another thread just so things aren't too cluttered. I would like
to a follow up questions just to make sure I understand things so please forgive
me if it seems repetitive.
To clarify I was wondering what would happen if the Bat/Alt Master Switch failed
completely. Would this not immediately remove all power to the main bus on the
Z12? If so, how would the aux alternator field be energized if located on the
main bus?
Cheers
Les
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=471857#471857
Message 11
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| Subject: | A treasure trove of data . . . |
"Peter" <peter@peter2000.co.uk> has gifted us with about
20GB of data consisting of operation, maintenance,
service and misc data on a mountain of aviation
interests.
Not quite sure how I'll try to make this available
to the community.
I don't think I'm going to post all of it on aeroelectric.com
but I have combined his and my documents related to Cessna's
at . . .
http://tinyurl.com/n2tfs6t
As I get time, I'll post the rest of the airframe specific documents.
Beech will be next. There's also extensive libraries on Piper,
Mooney, et. als. Here's a cut-n-paste of the table of contents.
AA-5 7/27/2016 2:10:36 AM File folder R
ACK 7/27/2016 2:10:36 AM File folder R
acukwik 7/27/2016 2:10:37 AM File folder R
AeroPac Tow 7/27/2016 2:10:37 AM File folder R
Aircraft Registers 7/27/2016 2:10:39 AM File folder R
AmeriKing 7/27/2016 2:10:39 AM File folder R
Apollo-UPS 7/27/2016 2:10:41 AM File folder R
ARINC 7/27/2016 2:10:41 AM File folder R
Arnav 7/27/2016 2:10:41 AM File folder R
Artex 7/27/2016 2:10:41 AM File folder R
ASA Flight Timer 7/27/2016 2:10:42 AM File folder R
Aspen 7/27/2016 2:10:43 AM File folder R
Astro-Tech 7/27/2016 2:10:43 AM File folder R
Avidyne 7/27/2016 2:10:44 AM File folder R
Badin-Crouzet 7/27/2016 2:10:44 AM File folder R
Becker 7/27/2016 2:10:44 AM File folder R
Beech 7/27/2016 2:10:54 AM File folder R
Beech-Starship-MM 7/27/2016 2:10:58 AM File folder R
Bellanca 7/27/2016 2:10:59 AM File folder R
Bendix 7/27/2016 2:11:01 AM File folder R
Bose 7/27/2016 2:11:01 AM File folder R
Brittain 7/27/2016 2:11:01 AM File folder R
CAV 7/27/2016 2:11:01 AM File folder R
Century 7/27/2016 2:11:03 AM File folder R
Cessna 7/27/2016 2:12:13 AM File folder R
Cleveland 7/27/2016 2:12:29 AM File folder R
Collins 7/27/2016 2:12:30 AM File folder R
Continental 7/27/2016 2:12:33 AM File folder R
DAC 7/27/2016 2:12:36 AM File folder R
Davtron 7/27/2016 2:12:42 AM File folder R
Diamond 7/27/2016 2:12:42 AM File folder R
DUAL 7/27/2016 2:12:42 AM File folder R
Eaton 7/27/2016 2:12:42 AM File folder R
ElectronicsInternational 7/27/2016 2:12:42 AM File
folder R
Emtac 7/27/2016 2:12:42 AM File folder R
Freeflight 7/27/2016 2:12:43 AM File folder R
Garmin 7/27/2016 2:13:26 AM File folder R
Garmin-Apollo-unclassified 7/27/2016 2:13:55 AM File
folder R
Gas Alert 7/27/2016 2:13:55 AM File folder R
Gill 7/27/2016 2:13:55 AM File folder R
Honeywell-Bendix-King 3/28/2017 3:37:54 AM File folder R
ICAO-docs 7/27/2016 2:14:44 AM File folder R
Icarus 7/27/2016 2:14:47 AM File folder R
Icom 7/27/2016 2:14:48 AM File folder R
Insight 7/27/2016 2:14:49 AM File folder R
Janitrol 7/27/2016 2:14:49 AM File folder R
JP Instruments 3/26/2017 11:10:20 AM File folder R
Kelly 7/27/2016 2:14:50 AM File folder R
KGS 7/27/2016 2:14:50 AM File folder R
L3 - BF Goodrich 7/27/2016 2:14:53 AM File folder R
Lightspeed 7/27/2016 2:14:53 AM File folder R
Lowrance 7/27/2016 2:14:53 AM File folder R
Lycoming 7/27/2016 2:14:59 AM File folder R
Magellan 7/27/2016 2:15:55 AM File folder R
Magic Tow 7/27/2016 2:15:55 AM File folder R
Michelin 7/27/2016 2:15:55 AM File folder R
Microair 7/27/2016 2:15:55 AM File folder R
MidContinent 7/27/2016 2:15:55 AM File folder R
Misc 7/27/2016 2:15:56 AM File folder R
Misc-NON-avionics 7/27/2016 2:15:58 AM File folder R
Misc-Pinouts 7/27/2016 2:15:59 AM File folder R
Mooney 7/27/2016 2:16:07 AM File folder R
Mountain High 7/27/2016 2:16:08 AM File folder R
Moving-Terrain 7/27/2016 2:16:08 AM File folder R
MT Propeller 7/27/2016 2:16:08 AM File folder R
Narco 7/27/2016 2:16:10 AM File folder R
Navworx 7/27/2016 2:16:10 AM File folder R
Northern-Airborne 7/27/2016 2:16:10 AM File folder R
Northrop-Grumman-LITEF 7/27/2016 2:16:17 AM File folder R
Partenavia 7/27/2016 2:16:17 AM File folder R
Pentax 7/27/2016 2:16:17 AM File folder R
Phonak 7/27/2016 2:16:17 AM File folder R
Piper 7/27/2016 2:16:42 AM File folder R
PowerFlarm 7/27/2016 2:16:42 AM File folder R
Precision Airmotive 7/27/2016 2:16:42 AM File folder R
Precision Aviation 7/27/2016 2:16:42 AM File folder R
Prestolite 7/27/2016 2:16:42 AM File folder R
PS Engineering 7/27/2016 2:16:43 AM File folder R
Radiorax 7/27/2016 2:16:44 AM File folder R
Rockwell 7/27/2016 2:16:47 AM File folder R
Sandel 7/27/2016 2:16:49 AM File folder R
Sandia 7/27/2016 2:16:49 AM File folder R
Shadin 7/27/2016 2:16:50 AM File folder R
Sigmatek 7/27/2016 2:16:50 AM File folder R
Sigtronics 7/27/2016 2:16:50 AM File folder R
Skyconnect 7/27/2016 2:16:51 AM File folder R
Skyforce 7/27/2016 2:16:51 AM File folder R
Sky-Tec Starter 7/27/2016 2:16:50 AM File folder R
Socata 7/27/2016 2:17:12 AM File folder R
S-Tec 5/1/2017 1:48:10 AM File folder R
Technisonic 7/27/2016 2:17:13 AM File folder R
Tecnam 7/27/2016 2:17:13 AM File folder R
TKS 7/27/2016 2:17:13 AM File folder R
Trig 7/27/2016 2:17:13 AM File folder R
Trimble 7/27/2016 2:17:14 AM File folder R
UPSAT 7/27/2016 2:17:15 AM File folder R
Western Avionics 7/27/2016 2:17:16 AM File folder R
Whelen 7/27/2016 2:17:16 AM File folder R
Yaesu 7/27/2016 2:17:16 AM File folder R
Bob . . .
Message 12
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| Subject: | Re: Alternator Question - Redux |
Les,
I added a PC 310 battery through a 40 amp relay to my main bus on the Z12.
It is switched by the switch that fed my e bus. I no longer have the e bus
but still have dual power feeds to the main bus.
On Aug 14, 2017 11:13 AM, "kearney" <kearney@shaw.ca> wrote:
>
> Bob
>
> Thank you for your comments and explanations they were most helpful.
>
> I have started another thread just so things aren't too cluttered. I would
> like to a follow up questions just to make sure I understand things so
> please forgive me if it seems repetitive.
>
> To clarify I was wondering what would happen if the Bat/Alt Master Switch
> failed completely. Would this not immediately remove all power to the main
> bus on the Z12? If so, how would the aux alternator field be energized if
> located on the main bus?
>
> Cheers
>
> Les
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=471857#471857
>
>
Message 13
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| Subject: | Re: Alternator Question - Redux |
At 01:05 PM 8/14/2017, you wrote:
>
>Bob
>
>Thank you for your comments and explanations they were most helpful.
>
>I have started another thread just so things aren't too cluttered. I
>would like to a follow up questions just to make sure I understand
>things so please forgive me if it seems repetitive.
>
>To clarify I was wondering what would happen if the Bat/Alt Master
>Switch failed completely. Would this not immediately remove all
>power to the main bus on the Z12? If so, how would the aux
>alternator field be energized if located on the main bus?
But how does it fail completely? Get one of these
switches, choose any combinations of force/tools
you choose to disassemble/emulate a 'failure'.
Once your switch is sufficiently 'failed', then
deduce how the same condition can be repeated in
your airplane.
Most 'failures' are soft and progressive. Something
becomes intermittent or quits and is usually a function
of age and environmental conditions . . . not service
stresses.
I have only once in my lifetime had to diagnose and
deal with 'failure' of a Honeywell toggle switch in
an airplane. It was a spring loaded toggle used as
press to test on BeechJet ground fault system.
The OPERATING current carried by this switch was
a few tens of milliamps. Upon opening the panel
and testing the switch with a meter, it was indeed
found to be open circuit on the normally open
side.
The tech I was working with was ready to start
filling out the paperwork to bet a new switch.
I asked him to hold off for a few minutes. I
got a small bench supply out of the lab and
drug an extension cord into the airplane. I
unhooked one wire from the switch so as not
to 'power the airplane' and put 28v at 10A
current limit on the switch. I then
wiggled the switch until it suddenly began
to show continuity across the 'failed' contacts.
In this case, the relatively high-current,
silver-cadmium contacts of the power rated
switch had never been blessed with enough
current flow to keep its contacts clean!
After a few dozen 10A whacks to the switch,
I put the wire back on and we signed off
the squawk. Didn't get to charge the customer
$200 for a new switch.
We have seen some switch failures on the
List.
http://tinyurl.com/yapmtot4
http://tinyurl.com/yd4tz8qd
We also had a rash of loose terminals
at the riveted joints on the Carling
toggle switches.
But none of those failures manifested as
a sudden hazard to flight.
the point is, be cautious about stirring
the worry-pot with "what ifs?" The the vast
majority of what ifs thrashed around on the
various forums are not well understood nor
backed up with historical data.
I wouldn't hazard a guess as to how many
GA aircraft have been flown over the last 100
years . . . certainly hundreds of thousands
if not millions. Yet system architectures and
materials used have not materially changed.
From the time they put the first battery in
a C120 to make it a C140 . . . up through the
pressurized 1986 P210, the battery contactors
have been made on the same, commercial grade
production lines.
Emacs!
The rocker switches have the same back-side
guts as the toggle switches sold by B&C and
made by Carling.
Emacs!
I'm certain that this same constellation
of components persisted for a decade or
two after 1986.
The point is, there is a field history in both
hardware and architectures that makes our
job here on the List easier . . . it suggests
that we need not waste a lot of time hypothesizing
and mitigating every conceivable component failure
while concentrating on failure tolerant architectures.
Z-12 as published represents a well considered
and field proven solution to the single battery,
two-alternator option for a light airplane.
Bob . . .
Message 14
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| Subject: | Re: Alternator Question - Redux |
After the engine is started and running, the battery is no longer supplying electrical
power to the aircraft. The alternator is. And the alternator is supplying
power to its own field. If the battery is then disconnected, nothing changes.
The alternator continues to power the electrical system including the
alternator field. Without the battery, the voltage might be unstable and vary
plus and minus one volt or so from the voltage regulator set point. But electrical
loads will still work.
If both halves of the Master/Alternator switch fail simultaneously, then yes,
the electrical system will go down. But that switch would have to completely
fall apart inside in order for that to happen, which is unlikely. If it did
fall apart, it would most likely happen when the switch is turned on or turned
off, not during cruise. I would not worry about it. There are other things
more likely to fail, like the engine or prop or a pilot.
You could use Bob's favorite electrical architecture , Z-13/8. The aux alternator
output connects to the battery, not directly to the bus.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=471869#471869
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