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Z11 "Generic Electrical system" with Dual Electron

 
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nuckolls.bob(at)aeroelect
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PostPosted: Wed Apr 01, 2020 9:18 am    Post subject: Z11 "Generic Electrical system" with Dual Electron Reply with quote

Quote:


The Ignition is the critical item. I am comfortable loosing power to all the electronics other than the ignition, therefore the electrical system architecture is being designed to accommodate it.

Why settle for that . . . and the expenses associated
with it? When it might be easy to keep the whole
panel lit up?



Quote:
Kind of......I considered the diagram but not the architecture. Dual alternators, brownout bus, it seemed complex for my application. My perception is electrical demands for EFI are large compared with my choice of ignition at 1.4A total. Since both ignitions tied to a single battery was not failure tolerant , the SureFly small second battery (12V 8Ahr is $50) seemed simple.
Do you have room for a second alternator? The
brownout bus is optional dependent on equipment
installed. So is the battery bus. Remember, these
are architecture drawings with features that
address specific needs . . . if the need doesn't
exist, the feature is deleted.

The second alternator could be as small/light as
an SD8 . . . have you conducted a load analysis?
Do you KNOW what loads are supported under your
anticipated flight conditions?

Quote:
So lets reconsider that as archetecure and see what we come up with.

I have integrated the Architecture into my diagram, and removed the Aux Battery. The load on the Engine bus will be less than 5A so I will use a switch instead of a solenoid.

powered from what source? How long is the feeder from
that source to the switch?

Quote:
I removed the Battery Bus to avoid a human error that might deplete the battery out in the bush.

What accessories are on your airplane that would
benefit from a battery bus? If none, then no
bus necessary.


Quote:
If the power supply from the ALT side of the master solenoid fails, the
engine dies until the switch is flipped by reliable human action.
Not ideal. A diode to replace the switch eliminates human failure.

Then there's something wrong with the architecture . . .
one failure shuts off BOTH ignitions?

How so? Are you talking about the alternator?
The battery supports ALL loads in the event of
alternator failure.

Quote:
The next step I see is to remove the engine bus, bolt both power wires to the Battery side of the master solenoid. Now I am chasing my tail back to where I was. But lets say I did that. If the Solenoid fails open, then the engine is battery powered while the rest of the ship is powered by the alternator.

Contactors just don't do that in flight. Wiring
that controls contactors might . . . a bad crimp
turns loose of a wire. But that's a craftsmanship
issue. If we're going to craft firewalls for
craftsmanship . . . well . . . you can see where
that leads. But let's assume that your contactor
opens in flight for any reason. How would you
become aware of it?

Quote:
I think you already discussed months ago, but it looks to me like the Engine Bus duplicates the Essential bus.

The 'essential' bus was originally crafted to
quickly minimize loads during alternator-out
operations and later (Z13/Cool operations
with an itty-bitty standby alternator i.e.
and ENDURANCE bus.

Later it kinda morphed into a bus for
brownout sensitive loads whether or not
the endurance feature was needed.

Now it has a big brother intended to
support electrically dependent engines
every need including fuel management,
fuel injection, ignition and (if needed)
engine management instrumentation.

Do you have any electro-whizzies that
address engine ops over and above
the ignition system(s)? How is this
airplane to be used? Night ops? Extended
cross-country over unfriendly terrain?
IFR?



Bob . . .


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bcone1381



Joined: 25 Apr 2017
Posts: 42
Location: Southeast Michigan

PostPosted: Thu Apr 02, 2020 5:45 am    Post subject: Re: Z11 Reply with quote

Quote:
Why settle for that . . . and the expenses associated
with it? When it might be easy to keep the whole
panel lit up?


Simplicity was why I would settle for it. You say "Easy to keep it all lit up." A battery seemed simple and easy. I just read your "Thoughts on Standby Batteries."

http://forums.matronics.com/viewtopic.php?t=16775265
Quote:

Do you have room for a second alternator? The
brownout bus is optional dependent on equipment
installed. So is the battery bus. Remember, these
are architecture drawings with features that
address specific needs . . . if the need doesn't
exist, the feature is deleted.

The second alternator could be as small/light as
an SD8 . . . have you conducted a load analysis?
Do you KNOW what loads are supported under your
anticipated flight conditions?


I am familiar with the SD8. It is the standby alternator of choice if thats the way I need to go. I have room for it.

Load Analysis.
Normal Continuous load is 6.57A.
Normal Intermittent load is 2.5A for a single standby fuel pump.
Essential "Battery only" load requirements is 2.74A
The next quote regards the Alternate Engine Bus Switch
Quote:
powered from what source? How long is the feeder from
that source to the switch?

The Engine Bus Alternate Power switch I proposed is powered from the battery side of the master solenoid, and would carry a max normal load of 1.8A. It would be 24 inches from the solenoid, and 24 from the Engine Bus.
[quote]
Quote:
The battery supports ALL loads in the event of
alternator failure.

I agree. I was wrong.
Quote:
Do you have any electro-whizzies that
address engine ops over and above
the ignition system(s)? How is this
airplane to be used? Night ops? Extended
cross-country over unfriendly terrain?
IFR?


Engine Electro-Whizzes.....The engine is a Lycoming IO-360 fuel injected using mechanical Bendix RSA fuel injection and Mechanical Fuel Pump. The FI requires no electrical power for normal operation. It has a single backup electric fuel pump that is normally off. An Engine Monitoring System supplies all my engine instrumentation. There are no other engine related electro-whizzes.

The mission is DAY VFR. The mission also includes Cross Country over unfriendly terrain.


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nuckolls.bob(at)aeroelect
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PostPosted: Thu Apr 02, 2020 8:11 am    Post subject: Z11 "Generic Electrical system" with Dual Electron Reply with quote

At 06:09 PM 4/1/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>

Bob, In figure Z-01, Should the brownout bus fuse be increased in size from 10 amps to 30 amps?
Since that fuse is in series with other fuses, we wouldn't want a short circuit to blow two fuses.

Good observation . . . fuses, wire sizes and bus
loads are evolving . . .

Speaking of evolution, I'm still wrestling with the
notion of driving the crowbar ov breaker bus extension
through a ATC fuse on the fuseblock. I cannot guarantee
that every future builder would use a breaker having
I(squared)t characteristics small enough to avoid
popping that fuse.

The fusible link is still the stone simple, most
convenient way to bring power from the fuseblock
terminal to the circuit breaker. I'm researching
sources for on-purpose fusible link wire in bulk.
Much more convenient . . . than the legacy kits
we introduced 20+ years ago.

Keep up the discerning observations my friend!



Bob . . .


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nuckolls.bob(at)aeroelect
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PostPosted: Thu Apr 02, 2020 11:59 am    Post subject: Z11 "Generic Electrical system" with Dual Electron Reply with quote

At 11:20 AM 4/2/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: "bcone1381" <bcone1964(at)gmail.com>


> Why put a switch in series with the E-Bus diode?
> I suggest that switch be eliminated. If it is not installed, it can not fail.


Merely Personal preference.....I like an avionics switch. The avionics will be on the essential bus.

In Bob's book he says that an avionics switch is a single point failure for every item on the avionics bus. This design fixes that senecio. The Switch and the Diode are used between the main and essential buses to avoid the main bus from ever drawing power through the essential bus.

. . . except the avionics master has offered
no value in the operation or cost of ownership
in aircraft for about 40 years . . . maybe more.



Bob . . .


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PostPosted: Fri Apr 03, 2020 6:29 am    Post subject: Z11 "Generic Electrical system" with Dual Electron Reply with quote

At 08:45 AM 4/2/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: "bcone1381" <bcone1964(at)gmail.com>


> Why settle for that . . . and the expenses associated
> with it? When it might be easy to keep the whole
> panel lit up?


Simplicity was why I would settle for it. You say "Easy to keep it all lit up." A battery seemed simple and easy.

Okay, this is a bush plane. I presume you are
hoping to launch pleasurable excursions into
territories where being able to 'get back'
is a whole lot more important that 'getting
there'.

Cranking battery expectations in bush aircraft
are second only in magnitude to batteries
in float planes. Imagine just having pushed
away from the mooring only to find yourself
at the mercy of wind and currents!

Given that circumstance, I trust you're
planning on periodic battery capacity and load
checks with protocols that call for battery
replacement long before it becomes a risk?

So under what conditions would that battery
become unavailable for running at least one
if not both ignition systems?

Further, given the size of your engine,
do I surmise that the ship's battery is
going to be rather robust in the first
place?

The 1 mA parasitic drain of an ignition
system in the OFF condition would consume
1 Ah of energy every 40 days . . . a trivial
concern suggesting that disconnecting that
load from the battery is of little value
except during long term storage of the
airplane . . . which could be managed
by pulling a fuse.

An SD8 standby alternator would weigh
less than an 8Ah battery, requires
close to zero preventative maintenance
and carry 8+ amps of load as long as the
fan is running. Given your stated running
loads, the SD8 would keep things lit up
until you run out of gas, a PC680 battery
at minimum capacity for continued airworthiness
would carry your 7A load for 0.8 x 120
minutes . . . one way or another, you'll
be on the ground long before the panel
goes dark.

A standby battery wired for the sole
purpose of supporting one ignition system
is something akin to what must be millions
of first-aid kits bought and carried around
by a worrying public . . . never having
been needed to salve a skinned knee or
band-aid some small injury . . . if ever.

If it were my airplane, I'd go for Z13-8
with both ignitions on the E-bus. Since
the e-bus is cold when parked, no controls
on ignition power are needed. FMEA for
Z13-8 is about as robust as anything you
can install . . . those ignition systems
are never going to be deprived of necessary
power.


Bob . . .


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bcone1381



Joined: 25 Apr 2017
Posts: 42
Location: Southeast Michigan

PostPosted: Fri Apr 03, 2020 11:59 am    Post subject: Re: Z11 Reply with quote

Quote:
Cranking battery expectations in bush aircraft
are second only in magnitude to batteries
in float planes.

Given that circumstance, I trust you're
planning on periodic battery capacity and load
checks with protocols that call for battery
replacement long before it becomes a risk?


Your book helped me understand the great value of Battery Checks, so much so that I am now evangelistic on the topic. The crowd believes “If the starter cranks it Good!” and tough to reason with. Its a Cognitive Bias issue we all are susceptible to.

Bob, You understand our need for guidance. Thank you for your Leadership that enables us. Thinking "Bush Mission" alone helps clarify things a great deal

Quote:
So under what conditions would that battery
become unavailable for running at least one
if not both ignition systems?


In the bush.....on the ground and in the air.

On the ground in the bush, the battery will be unavailable from running the ignition if I shut down and leave the master switch on for ten hours with an 0.8A draw on the master solenoid. A distraction before completing the shut down flow is a likely cause. This may be that I
-go to sleep or
-go on a long hike or
-go fly fishing.

(A solid state solenoid with a milliamp draw discussion will take us off topic.)

In the Air....

Our rules are “one single failure at at time” when playing the “what if game”. In the air, if that single failure is the alternator, then the engine keeps running until battery exhaustion. By downloading the main bus I get about 80% of 6 hours. Then the alternator powers the engine bus even if
-One of five bolts at the battery, ground, solenoid or engine bus loosens.
-Open Circuit in one of three wires.
-Battery failure

Max range in the Patrol is 9 hours. Alaska and Northern Canada will utilize more than 6 hours.
Quote:
The 1 mA parasitic drain of an ignition
system in the OFF condition would consume
1 Ah of energy every 40 days . . . a trivial
concern suggesting that disconnecting that
load from the battery is of little value
except during long term storage of the
airplane . . . which could be managed
by pulling a fuse.


Those were my thoughts. I’ll have a Battery maintainer at the hangar and can otherwise manage this small drain.
Quote:
An SD8 standby alternator would weigh
less than an 8Ah battery, requires
close to zero preventative maintenance
and carry 8+ amps of load as long as the
fan is running. Given your stated running
loads, the SD8 would keep things lit up
until you run out of gas, a PC680 battery
at minimum capacity for continued airworthiness
would carry your 7A load for 0.8 x 120
minutes . . . one way or another, you'll
be on the ground long before the panel
goes dark.

A standby battery wired for the sole
purpose of supporting one ignition system
is something akin to what must be millions
of first-aid kits bought and carried around
by a worrying public . . . never having
been needed to salve a skinned knee or
band-aid some small injury . . . if ever.

If it were my airplane, I'd go for Z13-8
with both ignitions on the E-bus. Since
the e-bus is cold when parked, no controls
on ignition power are needed. FMEA for
Z13-8 is about as robust as anything you
can install . . . those ignition systems
are never going to be deprived of necessary
power.


I attached an image of the Z13-8 architecture combined with the engine bus of Z-01. This answers your questions. Now, I'll post this and then study my digram and ask a few questions for the listening audience.

Brooks


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bcone1381



Joined: 25 Apr 2017
Posts: 42
Location: Southeast Michigan

PostPosted: Fri Apr 03, 2020 2:56 pm    Post subject: Re: Z11 Reply with quote

Nuckolls’ says
1) Things break
2) Design the system so that when things break no immediate hazard is created.
3) Things needed for comfortable termination of flight requires back up or special consideration to insure operation and availability.

With that in mind, here are some thoughts on my crude block diagram in post #19 where I combined Z13/8 architecture with the dual feeder engine bus portion of Z01.Think of each point as an individual hypothesis. The musings do not build on themselves.

First, lets keep the engine running and consider the ENGINE BUS

1) The normal switch position for the ALT ENG BUS Feed must be open to prevent power feeding the battery through the ENG BUS.

2) I desire to place the ENG BUS firewall forward but I have reliability concerns due to water, heat, oil pollutants in the engine compartment. There must be an Ugly Environment fuse holder out there on the market place.

3)“What If” Smoke enters the Cockpit plus acrid smell of electrical due to wrench that falls onto the E-bus. Typical Procedures might be “BATT Master off, ALT off.” But now Engine dies with the ALT ENG BUS FEED open which is the normal position. This Violates Rule #2.

Possible Resolutions
    1) Source the Normal ENG BUS Feed circuit from the BATT side of Master Solenoid thru a diode instead of the ALT side of the solenoid. Source it’s alternate feed from the ALT side of the Master Solenoid through a switch.
    I see a problem…the diode failure shuts down the engine. 



    2) Source the Normal Feed to ENG BUS from the BATT side of the Batt Master Solenoid without a switch or a doiode or alternate feed circuit.
    Consequence, the engine bus has no alternate feed. Seems reliable but It violates Rule #3.


    3)Remove the Engine Bus, then power each ignition from different sources.
    Attach one Ignition power supply directly to the Battery using a simple ring terminal, and attach the other Ignition’s ring terminal to one of the following

    -BATT side of the Battery Master Solenoid, or
    -the E-BUS terminal bolt, or
    -the ALT side of the Master Solenoid.

    This eliminates having all your engines in one basket. Any single failure will not create an immediate hazard.


    4) Maybe a bus is overkill for merely two 0.7A circuits.

E-BUS
Remove the in-line fuse on the BATT - E BUS circuit to improve reliability. The Z-11 has no fuse from the Batt to the Batt Bus, but a 7A fuse on the Batt Bus - Ess Bus circuit. (I don’t know what is prudent and a best practice.)
      Code:


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      bcone1381



      Joined: 25 Apr 2017
      Posts: 42
      Location: Southeast Michigan

      PostPosted: Sun Apr 05, 2020 9:43 am    Post subject: Re: Z11 Reply with quote

      In Post #20, I ask myself about resolution to Smoke in Cockpit due to electrical, bus failure. I am offering a diagram with the solution that I think I like.

      Its a simplified Z13/8 architecture with one ignition powered from the battery terminal and the other powered from the Battery side of the Master Solenoid.

      Should the Circuit from the Battery to the E-Bus have a fuse-link? I ask because the Z-13/8 diagram’s the Main bus and E-Bus circuit does not.


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