Today's Message Index:
----------------------
1. 02:48 AM - Re: EFIS brown out protection (Robert L. Nuckolls, III)
2. 03:40 AM - Re: EFIS brown out protection (Bob-tcw)
3. 09:37 AM - Re: EFIS brown out protection (Gig Giacona)
4. 10:18 AM - Re: Re: EFIS brown out protection (Robert L. Nuckolls, III)
5. 10:24 AM - Re: Re: EFIS brown out protection (Bob-tcw)
6. 10:43 AM - Re: Re: EFIS brown out protection (Robert L. Nuckolls, III)
7. 10:58 AM - Re: Fusible Links and Bus Interconnects (tx_jayhawk)
8. 01:18 PM - Re: Re: Fusible Links and Bus Interconnects (Robert L. Nuckolls, III)
9. 02:06 PM - Re: Re: EFIS brown out protection (Bob-tcw)
10. 02:08 PM - Re: Re: EFIS brown out protection (Charlie England)
11. 02:58 PM - Re: Re: EFIS brown out protection (Bob-tcw)
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Subject: | Re: EFIS brown out protection |
At 08:33 PM 3/26/2009, you wrote:
>Would an aux battery feed to the E Buss through a solid state
>contactor keep the voltage from sagging if the contactor is
>energized by the starter switch. The E Buss feed from the Main
>Buss is through a diode.
>
>I will appreciate any facts and/ or opinions,
I'm aware of no solid state relays that behave
like a metallic switch. They work well to effect
on/off control to a load that is never a power
source . . . like landing lights, pitot heat,
blowers, etc.
However, solid state relays with the lowest
ON resistance use power MOS-FET transistors.
These critters come with a built in power diode
across the transistor's control structure.
This means that when the relay is OFF, power
can back-feed from the "load" back toward the
"source".
What you've proposed may work as long as this
potential for reverse current flow is an
acceptable feature in your overall design
goal. Figure Z-10/8 shows one way that a
relay can be used to isolate an aux battery
during engine cranking such that brownout
transient does not propagate from main battery
to the brown-out protection battery.
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z10-8A1.pdf
Another scheme could simply treat the Aux
Battery as a non-cranking device wired like
Z-30 and supplying e-bus alternate power from
the aux battery bus.
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z29K_30K.pdf
In this case one simply closes the E-bus alternate
feed switch and leaves the aux battery contactor open
while cranking the engine.
There are variations on the theme you can consider
and it's not necessarily given that a solid state
relay is unsuitable to the task. Just be aware
of and account for its reverse power flow feature.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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Subject: | Re: EFIS brown out protection |
Paul, One alternative to an auxiliary battery for voltage sag
protection is a product we developed at TCW Technologies. Intelligent
Power Stabilizer, IPS, provides regulated power to critical electronics
with battery voltages ranging from 5-15 volts. This product was
specifically developed to keep EFIS, GPS and engine monitors up and
running during engine starting. It weighs less than 1 lb and requires
no maintenance. All the details are avialable at www.tcwtech.com
Thanks,
Bob Newman
TCW Technologies, LLC.
----- Original Message -----
From: Paul Eckenroth
To: aeroelectric-list@matronics.com
Sent: Thursday, March 26, 2009 9:33 PM
Subject: AeroElectric-List: EFIS brown out protection
Would an aux battery feed to the E Buss through a solid state
contactor keep the voltage from sagging if the contactor is energized by
the starter switch. The E Buss feed from the Main Buss is through a
diode.
I will appreciate any facts and/ or opinions,
Paul Eckenroth
N509RV
Message 3
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Subject: | Re: EFIS brown out protection |
I have a question about this device. With the Dynon 180 and other EFIS/EMS systems
the aircraft voltage is measured from the same wire that powers the unit.
Doesn't this device defeat that ability to measure voltage?
rnewman(at)tcwtech.com wrote:
> Paul, One alternative to an auxiliary battery for voltage sag protection is a product we developed at TCW Technologies. Intelligent Power Stabilizer, IPS, provides regulated power to critical electronics with battery voltages ranging from 5-15 volts. This product was specifically developed to keep EFIS, GPS and engine monitors up and running during engine starting. It weighs less than 1 lb and requires no maintenance. All the details are avialable at www.tcwtech.com (http://www.tcwtech.com)
>
> Thanks,
> Bob Newman
> TCW Technologies, LLC.
>
>
>
> ---
--------
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=236363#236363
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Subject: | Re: EFIS brown out protection |
At 11:34 AM 3/27/2009, you wrote:
>
>I have a question about this device. With the Dynon 180 and other
>EFIS/EMS systems the aircraft voltage is measured from the same wire
>that powers the unit. Doesn't this device defeat that ability to
>measure voltage?
How so? ALL instruments display what they measure
at the point of interest determined by design goals
of the manufacturer.
Bottom line is that watching the voltage or current
at any point in the aircraft has some diagnostic but
even less operational value. When it comes to a
resurrection of some system in your airplane,
probability of having EASY access to the most
useful measurement points is close to zero.
We've discussed the value of having alternator loadmeters
versus battery ammeters. We've studied the value of
knowing voltage on a host of "interesting" system nodes.
Some years ago I proposed a non-digital implementation of
the automotive diagnostics connector. See:
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Electrical_System_Diagnostics.pdf
That proposal brought 26 data points of interest to some
handy location for the purposes of doing system failure
diagnosis from the cockpit . . . with room to expand to
37 total.
The odds of really NEEDING to look at any one of those
points is tiny. But the FIRST time that access to a
data point buried in the guts of your airplane saves
you hours of trouble shooting time . . . the value
of installing such features takes a quantum leap
upward.
I've been privileged to mitigate dozens of problems
that had an airplane out of service for weeks if not
months. My success had more to do with getting access
to data than it was the deduction of what the data meant!
The value of any single measurement is predicated on
understanding its significance. The probability of any one
measurement being significant in the constellation of potential
troubleshooting tasks is small.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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Subject: | Re: EFIS brown out protection |
With equipment like the Dynon that only have a single power input, then the
ability to measure voltages below 12 volts is lost. (voltages above 12 volts
will read correctly) However, we have included a low voltage warning light
with the IPS system. Below 12.0 volts the light will illuminate.
Thanks,
Bob Newman
----- Original Message -----
From: "Gig Giacona" <wrgiacona@gmail.com>
Sent: Friday, March 27, 2009 12:34 PM
Subject: AeroElectric-List: Re: EFIS brown out protection
> <wrgiacona@gmail.com>
>
> I have a question about this device. With the Dynon 180 and other EFIS/EMS
> systems the aircraft voltage is measured from the same wire that powers
> the unit. Doesn't this device defeat that ability to measure voltage?
>
>
> rnewman(at)tcwtech.com wrote:
>> Paul, One alternative to an auxiliary battery for voltage sag
>> protection is a product we developed at TCW Technologies. Intelligent
>> Power Stabilizer, IPS, provides regulated power to critical electronics
>> with battery voltages ranging from 5-15 volts. This product was
>> specifically developed to keep EFIS, GPS and engine monitors up and
>> running during engine starting. It weighs less than 1 lb and requires
>> no maintenance. All the details are avialable at www.tcwtech.com
>> (http://www.tcwtech.com)
>>
>> Thanks,
>> Bob Newman
>> TCW Technologies, LLC.
>>
>>
>>
>> ---
>
>
> --------
> W.R. "Gig" Giacona
> 601XL Under Construction
> See my progress at www.peoamerica.net/N601WR
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=236363#236363
>
>
>
Message 6
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Subject: | Re: EFIS brown out protection |
At 12:16 PM 3/27/2009, you wrote:
>
>With equipment like the Dynon that only have a single power input,
>then the ability to measure voltages below 12 volts is lost.
>(voltages above 12 volts will read correctly) However, we have
>included a low voltage warning light with the IPS system. Below
>12.0 volts the light will illuminate.
Does the Dynon shut down its ability to display
voltages below 12.0? What is the significance of
knowing a transition across a 12.0 volt threshold?
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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Subject: | Re: Fusible Links and Bus Interconnects |
Hi Bob,
Thanks for the feedback...I re-reviewed 43.13 to try and better answer my own questions,
but there was still a few things from your reply I was not clear on.
> These notations suggest that connected devices should
> be adjacent to each other. If you gotta go 10" for the
> conductor, then so be it. But close proximity in
> the airplane is a design goal.
Is this just from a circuit protection standpoint (want it to be like "one" device)?
10" is ok...what about 2'?
> Z-13/20 was eliminated from the z-figures. After
> some considerable, afer-the-fact consideration I
> decided I could claim to have been hung over when
> I did it. It's just too clumsy. Z-12 or Z-14 are
> better integrations of an SD-20 with a larger main
> alternator.
I'm now sure I understand why this is? My problem with Z12 is that both alternators
are feeding the same point. If the connection from the main to ess bus
fails, you've lost both alternators. It seems preferable to have the standby
alt feed the e-bus more directly. Z14 has another battery, contactors, and other
complexity I chose not to pursue.
> Long lengths of wire (greater than 6" in the FAA
> world) need some form of fault protection. Unless
> your main bus is located within 6" of the breaker,
> then protection is generally advised. Further, it
> must be MUCH more robust than the 5A breaker which
> is expected to operate FIRST during a crowbar ov event.
>
I would be interested in learning the origin of the 6" rule (I could not find in
AC 43.13), but it still seems the wire already has circuit protection via the
circuit breaker. I'm not sure I understand why two circuit protection devices
are needed. There are obviously lots of power wires (for other loads) longer
than 6" with only one source of circuit protection, so I am not sure why this
is different?
> They don't want
> to be too short for thermal characteristics. 6"
> is a good number used on many cars. But certainly
> no longer.
6" is a max...2" is min? 3"?
THanks,
Scott
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=236393#236393
Message 8
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Subject: | Re: Fusible Links and Bus Interconnects |
At 12:54 PM 3/27/2009, you wrote:
>
>Hi Bob,
>
>Thanks for the feedback...I re-reviewed 43.13 to try and better
>answer my own questions, but there was still a few things from your
>reply I was not clear on.
>
>
> > These notations suggest that connected devices should
> > be adjacent to each other. If you gotta go 10" for the
> > conductor, then so be it. But close proximity in
> > the airplane is a design goal.
>
>Is this just from a circuit protection standpoint (want it to be
>like "one" device)? 10" is ok...what about 2'?
You have to make the go/no-go decision as to how
far you're willing to stretch contemporary
conventions. The goal is to minimize risks
to small gage feeders (by "small" we mean
much smaller than the battery and cranking
circuit wires). Occasionally we've needed to
attach some device directly to the bus or
other fat-wire feed power point in a TC
aircraft where the amount of wire exposed to
fault risk could be limited to 6" or so.
Folks traditionally up-tight with the burning
of ANY wire deduced that the hazards generated
were small. Same philosophy was applied to
fusible links in cars. Now, if you want to
go for 12" or 10-feet, that's your decision
and your responsibility for risk mitigation.
Are you going to double insulate the wire?
Extra special care to insure no damage that
might create a fault? The choice is yours.
I've recommended a fusible link as an upstream
protection for the 5A crowbar OV shut down
system. It's not a "rule" and would not perhaps
even be mentioned in 43.13.
My approach is to offer recipes for success
based on my personal observations of history
and experiences in analysis of failure mode
effects. But the ultimate magnitude and
nature of risk you're willing to assume is
your choice.
> > Z-13/20 was eliminated from the z-figures. After
> > some considerable, afer-the-fact consideration I
> > decided I could claim to have been hung over when
> > I did it. It's just too clumsy. Z-12 or Z-14 are
> > better integrations of an SD-20 with a larger main
> > alternator.
>
>I'm now sure I understand why this is? My problem with Z12 is that
>both alternators are feeding the same point. If the connection from
>the main to ess bus fails, you've lost both alternators. It seems
>preferable to have the standby alt feed the e-bus more
>directly. Z14 has another battery, contactors, and other complexity
>I chose not to pursue.
How do you loose connection between the main
bus and e-bus? Your presumption of risk is
no different than loss of connection between
the main bus and avionics bus in contemporary
TC aircraft. The weakest link in the legacy
main/avionics bus architectures is the avionics
master switch. As described in detail on the
website, the whole premise for installing such
a switch has evaporated based on new design goals
and product improvements over the past 40 years.
Further, even thought I've eliminated the AV master
from the Z-Figures, I've provided a second,
reduced power consumption pathway in the form of
an alternate feed directly from the battery.
Z-12 offers two power paths to the e-bus re-enforced
by two alternators driving a main bus with a reliability
history approaching that of prop bolts.
> > Long lengths of wire (greater than 6" in the FAA
> > world) need some form of fault protection. Unless
> > your main bus is located within 6" of the breaker,
> > then protection is generally advised. Further, it
> > must be MUCH more robust than the 5A breaker which
> > is expected to operate FIRST during a crowbar ov event.
> >
>
>
>I would be interested in learning the origin of the 6" rule (I could
>not find in AC 43.13), but it still seems the wire already has
>circuit protection via the circuit breaker.
One might accurately say it was pulled from a place
were the sun don't shine. Consider the wire protected
by the fusible link runs from bus to breaker, the breaker
protects wire(s) downstream AND complies with design
goals established by the crowbar ov protection
philosophy were a BREAKER is used in an airplane
otherwise protected by FUSES. If you have some OTHER
ov protection scheme, perhaps the 5A breaker, extended
bus wire AND fusible link is eliminated. In this case,
field power comes directly from the fuse block on a 5 or
7A fuse.
> I'm not sure I understand why two circuit protection devices are
> needed. There are obviously lots of power wires (for other loads)
> longer than 6" with only one source of circuit protection, so I am
> not sure why this is different?
A single protective device suffices when a circuit
branch from the bus (or fat wires) is located where
that power leaves the bus as in rows of breakers or
fuses. Once I tie onto the fat wires for extening power
from a fuse block to a panel mounted breaker, THAT
small wire becomes vulnerable. In observance of
the "rule of dark origins", the fusible link seems
easy and reasonable. Likelihood that the fusible link
will EVER be required to operate . . . exceedingly
low. But then, 99.99% of all breakers and fuses installed
in cars, airplanes, other vehicles and indeed your
house run the lifetime of the system never being
required to operate in defense of a fault condition.
So, knowing that . . . how far are you willing to
depart from legacy design goals? I cannot advise
you there. My design goals go to the simplest,
lowest cost, most robust implementation of
proven recipes for success.
Bob . . .
Message 9
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Subject: | Re: EFIS brown out protection |
The Dynon does not do anything strange with respect to reading bus voltage.
Some devices, such as the Dynon Efis, have a single power input which is
used to power the device as well as display the bus voltage. When they are
powered through a TCW IPS product then they receive regulated 12 volt power
regardless of the battery voltage. For bus voltages between 5-12 volts the
output of the IPS product will regulate the voltage supplied to the load
(EFIS), therefore, the EFIS will display a bus voltage of 12 volts. If
the bus voltage rises above 12 volts the IPS will pass that voltage on to
the load and therefore the bus voltage display on the EFIS will read
correctly. To provide a pilot warning for low bus voltage the IPS system
is supplied with a low voltage warning indicator to help annuciate a low
voltage condition.
Bob Newman
TCW Technologies
www.tcwtech.com
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Friday, March 27, 2009 1:33 PM
Subject: Re: AeroElectric-List: Re: EFIS brown out protection
> <nuckolls.bob@aeroelectric.com>
>
> At 12:16 PM 3/27/2009, you wrote:
>>
>>With equipment like the Dynon that only have a single power input, then
>>the ability to measure voltages below 12 volts is lost. (voltages above 12
>>volts will read correctly) However, we have included a low voltage
>>warning light with the IPS system. Below 12.0 volts the light will
>>illuminate.
>
> Does the Dynon shut down its ability to display
> voltages below 12.0? What is the significance of
> knowing a transition across a 12.0 volt threshold?
>
>
> Bob . . .
>
> ----------------------------------------)
> ( . . . a long habit of not thinking )
> ( a thing wrong, gives it a superficial )
> ( appearance of being right . . . )
> ( )
> ( -Thomas Paine 1776- )
> ----------------------------------------
>
>
>
Message 10
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Subject: | Re: EFIS brown out protection |
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 12:16 PM 3/27/2009, you wrote:
>>
>> With equipment like the Dynon that only have a single power input,
>> then the ability to measure voltages below 12 volts is lost.
>> (voltages above 12 volts will read correctly) However, we have
>> included a low voltage warning light with the IPS system. Below
>> 12.0 volts the light will illuminate.
>
> Does the Dynon shut down its ability to display
> voltages below 12.0? What is the significance of
> knowing a transition across a 12.0 volt threshold?
>
>
> Bob . . .
I *think* that the original point was that with a 'switcher' feeding a
regulated 13.8v to power the Dynon (being used as an engine/general
electrical system health monitor), the Dynon wouldn't be able to tell
the pilot that the bus voltage had begun to fall due to alternator or
other failures in the electrical system, since there's no separate
voltage monitor input on the Dynon. The 1st notice would be when the
switcher drops off-line & everything goes dark.
Charlie
Message 11
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Subject: | Re: EFIS brown out protection |
One other thing we did in the design of the IPS product was to set the
regulated output voltage to just below 12 volts so that under normal
conditions, i.e. alternator working properly, instruments like the Dynon
will show a proper bus voltage of around 14 volts. When there is an
alternator failure and the bus voltage starts to fall, there will be some
indication on the instrument volt meter. (movement from 14 to 12.6). When
you have an alternator failure the battery voltage rapidly falls from 14
volts down to about 12 to 12.6 where it sits whilst loads discharge the
battery. Also, if you miss that clue and you miss the low voltage
warning light illuminating at 12.0 volts, then somewhere around 8-9 volts of
bus voltage a lot of other electronic devices in the plane will start to let
you know that things have gone wrong. The good news is your EFIS will
still be up :)
-Bob Newman
TCW Technologies
----- Original Message -----
From: "Charlie England" <ceengland@bellsouth.net>
Sent: Friday, March 27, 2009 5:07 PM
Subject: Re: AeroElectric-List: Re: EFIS brown out protection
> <ceengland@bellsouth.net>
>
> Robert L. Nuckolls, III wrote:
>> <nuckolls.bob@aeroelectric.com>
>>
>> At 12:16 PM 3/27/2009, you wrote:
>>>
>>> With equipment like the Dynon that only have a single power input, then
>>> the ability to measure voltages below 12 volts is lost. (voltages above
>>> 12 volts will read correctly) However, we have included a low voltage
>>> warning light with the IPS system. Below 12.0 volts the light will
>>> illuminate.
>>
>> Does the Dynon shut down its ability to display
>> voltages below 12.0? What is the significance of
>> knowing a transition across a 12.0 volt threshold?
>>
>>
>> Bob . . .
>
> I *think* that the original point was that with a 'switcher' feeding a
> regulated 13.8v to power the Dynon (being used as an engine/general
> electrical system health monitor), the Dynon wouldn't be able to tell the
> pilot that the bus voltage had begun to fall due to alternator or other
> failures in the electrical system, since there's no separate voltage
> monitor input on the Dynon. The 1st notice would be when the switcher
> drops off-line & everything goes dark.
>
> Charlie
>
>
>
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