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Primary Power Diagram RV-14
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nuckolls.bob(at)aeroelect
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PostPosted: Thu Mar 16, 2023 11:35 am    Post subject: Primary Power Diagram RV-14 Reply with quote

At 01:06 PM 3/16/2023, you wrote:
Quote:
--> AeroElectric-List message posted by: "johnbright" <john_s_bright(at)yahoo.com>


Mudfly wrote:
> I have updated my Primary Power System diagram.
> Changes made:
> * Removed two shunts and replaced with one hall effect sensor.
> * Moved stdby alt field feed wire from avionics/essential bus to hot bat
> bus. The BUS SENSE WIRE needs to move too .


In fact, I'd jumper both terminals together and
take both -> AUX ALT switch ->20AWG->
breaker,->16AWG or larger-> to ->20FWL-> to
hot battery bus. This lets the more complex
regulator emulate the simple 'Ford' device

Quote:
> * Moved essential bus relay firewall fwd.
> *Removed current limiter between bat contactor and essential bus relay.
> *Added 4-post bus bar between battery contactor and main power bus.
> *Reduced wire size from 4awg to 6awg on pri alt b lead.
>
> Pending:
> *Possible removal of avionics switch and relay.
>
> Questions:
> * I moved the essential bus relay firewall fwd. My thinking was it
> provides improved crash protection. Is this a good plan, or was the
> 30 amp current limiter I had in place on previous diagrams sufficient and keep the
> relay aft of firewall?

Better that the power feeder is short . . .

Quote:
Do these relays hold up well FWF?

Anything that lives happily under the hood of a car
is in paradise under the cowl of an airplane.

Quote:
> * The stby alt fied wire is now fed from the hot bat bus. I show a 20awg
> FLW protecting that wire. Is this ok for through the firewall wires?
> *Is a FLW from the essential bus relay to the bus needed?

I leave it out

Quote:
> *I'm still figuring out relay types. I see most use a DPDT . For my setup
> could I use a SPST? I'm looking at N.O. at 30 amp models.
> Recommendations?

ANY 5-wire, 12v, SPDT relay will work fine irrespective
of its current rating. Remember, switch and relay ratings
are based on tens of thousands of operation SWITCHING
rated load. You're not going to cause these relays to
switch more than a fraction of rated load and then
perhaps probably way less that 1000 operations.

Quote:
> * I added a 4-post bus bar (Blue Sea System 2315 100 amp) between
> bat contactor and main power bus. Reasoning was based on the fuse
> block I'm using (Eaton 15711-20-21A) has one stud for power
> connections.
> My setup requires three
> wires; main power bus feed, pri alt field flw, and avionics relay feed.
> I don't see a good way to make those connections on that single stud. I have a good location for the
> 4-post bus bar that will allow for clean wire runs and easy serviceability. Thoughts?
> Thanks, Shawn


My thoughts re "Primary Power System 3-16-23.pdf":

Moving the esential bus relay firewall forward meets FAR 23.1361 which is good. The asterisks on Z101B imply the relay, bus, and diode are all FWF.

The standby alternator field and V Sense are still on the essential bus.

Why? Those wires should not see duty of any
kind EXCEPT during pre-flight and after main alternator
failure. It's good to minimize the wire and connections
between regulator and the bus driven by the s/b
alternator (hot battery).

Quote:
Rev 3-14-23 had the field on the battery bus and does not meet FAR 23.1361 because of the FLW, a relay would be required which is where putting it on the essential bus gets you a "free" relay. Z101B does meet the spirit of 23.1361 because it has a fuse, which cannot be used with a crowbar.

Which is why I suggested the 20FLW at the bus
end of that feeder.

Quote:
I measured 22 mA parasitic load in the V sense at 12.5V with Bus pin 6 disconnected, either SB1 or LR3, it will drain the battery if connected to the battery bus.

Not if it achieves connection through the AUX ALT
switch alone with the field supply.

Quote:
Perhaps a double pole standby alternator swtich, one pole for Bus pin 6 relaly and one pole for V Sense and LV Lamp.

That would be cool.


Quote:
In normal ops the Batt/Esntl switch would be at Batt, the Pri/Stby Alt
switch would be at Pri,

OOPS! A single mechanical device has command and
control over both power sources?

Quote:
and the Avionics switch would be on. If the Bat/Esntl switch is moved to Esntl the main bus stays alive with the now batteryless main alternator.
If the Pri/Stby Alt switch is moved to Stby the standby alternator's setpoint will go up by the diode drop.

In the fire-in-the-cockpit-main-master-off scenario you would move the Bat/Esntl switch to Esntl and the Pri/Stby Alt switch to Stby. This would power the essential bus at the standby alternator's stepoint.

I find written FMEAs to be a chore but I am not able to do them in my head.

I would make a table of possible switch settings and the result and seek a solution where the pilot does not have to ponder switches in an emergency and where no switch settings are a problem. What about a progressive main contactor/main alternator switch, an essential bus switch, and a double pole standby alternator switch with relay at battery bus for the field.

I vote no avionics switch and relay.

Yeah, keep it simple. The spirit and intent for
Z101 was: Any time DC PWR MASTER is in any ON
position, then there are NO hazardous conditions
for positions of any other switch.

In the event of low volts warning you accomplish
the following:

You say, "Oh shucks"

You drain your coffee cup and turn down the
stereo. Tell any kids in the back seat to
quiet down.

The point being that your system is configured
to never present you with an emergency situation.
There is TIME to consider and act with purpose.

You turn off primary alternator.

Turn ON s/b alternator and observe bus volts.

If present ship's loads exceed s/b alternator
capability, you should already KNOW what
combination of appliances can be carried by
the s/b alternator . . . practice this in
flight on a nice day.

If all extraneous loads are on the main bus
then you move ENG BUS ALT feed to ON.

Now, no potential hazards are imposed by
mis-positioning of any other switch.

Move EBUS AUX FEED to ON.

Move DC PWR MASTER to OFF and continue
flight to airport of intended destination.

Smoke in cockpit? ENGINE AUX and E-BUS AUX feeds
ON, everything else OFF.

So while you're getting squared away on your
intentional, inconvenient but controlled arrival
with the ground, see if smoke generation is
mitigated. If so, continue planning most
convenient alternate arrival.

If not, continue planning lowest risk, alternate
ASAP arrival.

Quote:
You might crimp multiple wires into one uninsulated terminal rather than adding studs. Ref https://docs.google.com/spreadsheets/d/1RhErTJKOWOL39Aw6lWJwQCgBQZzuCNf9GmS4MCgzcnc/edit?usp=share_link

It's easy to add a 2nd stud to the 15600 essential bus in order to remove an SPOF, loose nut opens both feeds. Snap the cap off, remove the bus strip, find the 2nd hex hole in the base for the stud head, notch the cap for the 2nd stud you add, reassemble. https://photos.app.goo.gl/ZKjbqnU3DfkUKNex2

Good call John, I'd forgotten about that
conversation many moons ago. A number of
builders have modified their fuse blocks to
add a second stud on the center bus.


Bob . . .

////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================

In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.


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david(at)carter.net
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PostPosted: Thu Mar 16, 2023 12:21 pm    Post subject: Primary Power Diagram RV-14 Reply with quote

On Thu, Mar 16, 2023 at 3:17 PM Charles Kuss <chaskuss(at)yahoo.com (chaskuss(at)yahoo.com)> wrote:

Quote:
What happens to your Hobbs count when either your EFIS dies or you upgrade your panel? Can you program the accumulated hours into the new unit??

 
Quote:
On Thursday, March 16, 2023, 12:06:05 PM EDT, David Carter <david(at)carter.net (david(at)carter.net)> wrote:

4. No need for a Hobbs meter - that is a built-in EFIS function. 


Look up the most recent value in the EFIS being replaced (or in your logbook if the EFIS is dead), and transfer that value to the configuration menu of the new EFIS.  I just did this last week in the GDU 460 that's in my new panel. I had noted the old value from the EDM 350 engine monitor before I removed it from the plane. In fact, I did that for both tach time & Hobbs time. 
I've never done this with an electrically-driven Hobbs meter, but I think it would be harder to run that ahead by 1,000 or so hours. 
  


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Mudfly



Joined: 04 Feb 2012
Posts: 37

PostPosted: Fri Mar 17, 2023 5:53 am    Post subject: Re: Primary Power Diagram RV-14 Reply with quote

Thanks David.
A/P dissconect CB or switch - Just to make sure we're on the same page
regarding your comment on pullable breaker or switch for the "autopilot servos". I assume you are referring to the Ray Allen servo, specifically
pitch trim?
I will be using the Garmin autopilot servos and I do have a switch for
those. However, I "think" those can be manually overridden by
reasonable stick forces. Not sure about other brand autopilot servos.
A runaway Ray Allen servo in elevator is a different story. I'm
still thinking about that scenario. Several factors to consider there.
How many seconds does it take the servo to go from trimmed position
to full deflection? Ray Allen says 19 seconds for full travel.
We're in trimmed flight (neutral position) so lets say 10 seconds.
You're flying along, autopilot on (of course dark stormy night). The Ray Allen pitch servo starts to run away..pitch down. Do the autopilot servos
initially try to compensate? If so, there's 2 seconds off the clock. You realize something isn't right and disconnect the autopilot. Next
reaction is to try and trim up using Cooley hat trim...2 more seconds off
the clock. Next you go for your disconnect CB or switch.. 2 more seconds.
The pitch trim servo is now disconnected. What position is it in after
6 seconds? Because that's where it's staying. You're probably diving
for the deck at this point. Time to focus on slowing down and figuring
out what speed you can maintain pitch control. You've got me beat by
4 seconds as far as trim tab position. My trim went to full deflection since
I don't have a manual disconnect. However, could it be possible that I
have the plane in a more stable condition because I've had hands on
stick and throttle, focused on instruments since autopilot disconnect?
Who knows. Something to figure out on a nice on a nice day during
flight testing.

Hobbs meter - I had the panel space and just old school I guess

Two B/U batteries - I want to be able to maintain flight attitude and
navigation capabilities, as normal as possible, if I need to secure
ships battery and pri/stby alternators due to electrical smoke/fire.
First sign of electrical smoke, I switch off main battery and alternators.
The B/U bats activate automatically providing power to PFD, GTN650,
and a few other nice to have items. If smoke continues, I switch off
B/U batts one at a time starting with the GTN650 and then PFD if smoke
continues. Then I'm left with AV30 SFD and Ipad.
That's the plan anyway:)
Shawn

[quote="david(at)carter.net"]Sorry for the additional reply, but I noticed a couple more things:3. Safety of fli.
ght - put the autopilot servos on a pullable breaker that is easy to identify & easy to reach, rather than on a fuse.
4. No need for a Hobbs meter - that is a built-in EFIS function. 
---
David Carter
david(at)carter.net ([email]david(at)carter.net[/email])

On Thu, Mar 16, 2023 at 11:37 AM David Carter <david> wrote:

[quote]1. I'd replace both ANLs with fusible links. I have the same pair of alternators set up this way. Simpler to install, marginally less weight. 2. Why two standby batteries when you have an aux alt? Standby batteries are limited in capacity (run time) and add weight & complexity. Aux alt runtime = duration of fuel remaining. I added a TCW Intelligent Power Stabilizer instead to deal with any voltage sag during starter operation. 
---
David Carter
david(at)carter.net ([email]david(at)carter.net[/email])

On Thu, Mar 16, 2023 at 10:33 AM Mudfly <shawntedwards> wrote:

[quote]--> AeroElectric-List message posted by: "Mudfly" <shawntedwards>

I think I'm nearing the end of my wannabe EE career and moving towards
production/installation. 
I'm attaching what I think will be my "final" plan.  I'm sure there are things
some would do differently.  I have run the realistic scenarios I can think of through my head and believe I have a plan for all.
It does have a couple of failure modes that will require simple checklist procedures to rectify.
I am pretty slow at installation.  If anyone notices an area that may be a
safety of flight issue, please let me know and I will make the necessary
changes.         
I appreciate the help from the members of this forum.   
Shawn




Read this topic online here:

[url=http://forums.matronics.com/viewtopic.php?p=510427#510427]http://forums.matronics.com/viewtopic.php?p=510427#510427[/url]




Attachments:

[url=http://forums.matronics.com//files/primary_power_system_3_16_23_242.pdf]http://forums.matronics.com//files/primary_power_system_3_16_23_242.pdf[/url]
[url=http://forums.matronics.com//files/stby_batts_interconneconnects_3_16_23_130.pdf]http://forums.matronics.com//files/stby_batts_interconneconnects_3_16_23_130.pdf[/url]



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Mudfly



Joined: 04 Feb 2012
Posts: 37

PostPosted: Fri Mar 17, 2023 9:00 am    Post subject: Re: Primary Power Diagram RV-14 Reply with quote

[quote="nuckolls.bob(at)aeroelect"]At 01:06 PM 3/16/2023, you wrote:
[quote]--> AeroElectric-List message posted by: "johnbright" <john_s_bright>


Bob and John.
Thanks again for being a regular contributors to my post.
I know it takes time to sit down and type the thorough replies you have
provided.
I'm still studying some things from your suggestions that I don't
fully understand. I want to at least appear to know what I'm talking
about.
Shawn


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PostPosted: Fri Mar 17, 2023 9:53 am    Post subject: Primary Power Diagram RV-14 Reply with quote

On Fri, Mar 17, 2023 at 9:54 AM Mudfly <shawntedwards(at)hotmail.com> wrote:

Quote:

shawntedwards(at)hotmail.com>
Thanks David.
A/P dissconect CB or switch - Just to make sure we're on the same page
regarding your comment on pullable breaker or switch for the "autopilot
servos". I assume you are referring to the Ray Allen servo, specifically
pitch trim?


I was referring to the Garmin GSA28 servos, but the comment would apply
equally (or more so) to the Ray Allen pitch trim servo. I have both on
pullable breakers, separated from the other (less important in an
emergency) breakers.
Panel design here:
https://davidcarter-media.s3.us-east-2.amazonaws.com/N87BP+Garmin+G3X+REV+39.pdf
Quote:
I will be using the Garmin autopilot servos and I do have a switch for
those. However, I "think" those can be manually overridden by
reasonable stick forces.


I'd recommend a pullable breaker rather than a switch. You already need
circuit protection, and you should very rarely need to turn these off, so
why put in another point of failure, cost, and weight (the switch)? I also
think that stick forces can override the Garmin servos, but in a real
emergency, who wants to be fighting the automation that's trying to kill
you? Better to be able to quickly & easily turn it off.
Quote:
Hobbs meter - I had the panel space and just old school I guess


Your plane, your money, your choice! Smile
[quote] Two B/U batteries - I want to be able to maintain flight attitude and
navigation capabilities, as normal as possible, if I need to secure
ships battery and pri/stby alternators due to electrical smoke/fire.
First sign of electrical smoke, I switch off main battery and alternators


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Mudfly



Joined: 04 Feb 2012
Posts: 37

PostPosted: Fri Mar 17, 2023 11:05 am    Post subject: Re: Primary Power Diagram RV-14 Reply with quote

[quote="david(at)carter.net"]On Fri, Mar 17, 2023 at 9:54 AM Mudfly <shawntedwards> wrote:
Nice looking panel David.
BTW. Looks like you live about 15 mins from me. Got a hangar
with room for an RV14? Cool


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PostPosted: Thu Mar 23, 2023 7:18 am    Post subject: Primary Power Diagram RV-14 Reply with quote

Quote:
Two B/UÂ batteries - I want to be able to maintain flight attitude and
navigation capabilities, as normal as possible, if I need to secure
ships battery and pri/stby alternators due to electrical smoke/fire.

Electrically promoted fire exterior to an appliance
is exceedingly rare and almost always caused by
a failure in craftsmanship.

Think about it. Smoke generally comes from overheated
insulation on wires. Circuit protection is provided
to prevent such issues.

Then there is smoke from combustion of some OTHER
material . . . okay. I'll give you choice of any
tools you like . . . whack away at any part of your
ship's electrical system to (1) create a spark
of sufficient heat to (2) ignite some flammable material
without (3) opening the circuit protection.

I would hope that by design and fabrication, your wiring
is mechanically secure, thoughtfully sized and protected
and your airplane is also free of materials that would promote
an in flight fire should an ignition source become available.

Most in flight fires are in front of the firewall
feed by fuel or oil. Shutting down the DC power is
effective only if the fire is fuel-fed and fuel
is electrically transported from tank to engine. If
it's oil fed . . . well . . . that's an especially
bad day in the cockpit.

Quote:
First sign of electrical smoke, I switch off main battery and alternators.
The B/U bats activate automatically providing power to PFD, GTN650,
and a few other nice to have items.  If smoke continues, I switch off
B/U batts one at a time starting with the GTN650 and then PFD if smoke
continues. Then I'm left with AV30 SFD and Ipad.

That's a busy plan-A to plan-B transition check list.
We know that smoke in the cockpit most
likely originates from inside a failed piece of
avionics . . . and it's generally limited to some
small component that does not pose risk of fire
to the rest of the airplane.

Further what's your planned maintenance protocol for the
batteries. How often cap-checked and with what
tools? What conditions for air-worthiness call for
replacement? Remember, batteries are like potted
plants. They need constant attention to maximize
performance.

I suggest you are building a fire-wall against a situation
that seldom if ever happens. I'm unaware of any effort to add such
features to TC aircraft . . . and I slogged through that
regulatory tar-pit for decades.

DIY OBAM system designers are fond of adding mitigation
for a constellation of in-flight problems that are
not demonstrated in practice. Mitigations that add
complexity to the Plan-A-to-Plan-B transition are
to be avoided in a time of elevated pucker-factor'

A fine example is what happened to crews in 737MAX
aircraft faced with unintended, commands from
software that was DRIVING the nose down with a MOTOR.
They were trained to drag out the check list!
PUNCH OFF the MOTOR DRIVEN flight control features and
fly the airplane . . . takes what . . . two, maybe
three seconds?

Your two-alternator, single battery system is about
a bullet-proof as you can get. Everything added
only drives up cost, weight and adds operational
complexity.


Bob . . .

  ////
  (o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================

In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.


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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Thu Mar 23, 2023 7:34 am    Post subject: Primary Power Diagram RV-14 Reply with quote

Regarding cap checking batteries, I recently became aware of this tool:

https://www.amazon.com/dp/B07F3NHHST?psc=1&ref=ppx_yo2ov_dt_b_product_details

On Thu, Mar 23, 2023 at 7:23 AM Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:

[quote] Two B/UÂ batteries - I want to be able to maintain flight attitude and
navigation capabilities, as normal as possible, if I need to secure
ships battery and pri/stby alternators due to electrical smoke/fire.
Electrically promoted fire exterior to an appliance
is exceedingly rare and almost always caused by
a failure in craftsmanship.

Think about it. Smoke generally comes from overheated
insulation on wires. Circuit protection is provided
to prevent such issues.

Then there is smoke from combustion of some OTHER
material . . . okay. I'll give you choice of any
tools you like . . . whack away at any part of your
ship's electrical system to (1) create a spark
of sufficient heat to (2) ignite some flammable material
without (3) opening the circuit protection.

I would hope that by design and fabrication, your wiring
is mechanically secure, thoughtfully sized and protected
and your airplane is also free of materials that would promote
an in flight fire should an ignition source become available.

Most in flight fires are in front of the firewall
feed by fuel or oil. Shutting down the DC power is
effective only if the fire is fuel-fed and fuel
is electrically transported from tank to engine. If
it's oil fed . . . well . . . that's an especially
bad day in the cockpit.

First sign of electrical smoke, I switch off main battery and alternators


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