Today's Message Index:
----------------------
1. 05:43 AM - Re: Dynon D-180 & flickering LEDs (Robert L. Nuckolls, III)
2. 07:54 AM - PM alternator capacitors . . . (Robert L. Nuckolls, III)
3. 12:18 PM - Re: Z-19 Function (Robert L. Nuckolls, III)
4. 12:25 PM - Re: Real life lessons in wire ratings . . . (Jay Hyde)
5. 12:28 PM - Re: Real life lessons in wire ratings . . . (Jay Hyde)
6. 12:59 PM - Re: Real life lessons in wire ratings . . . (rayj)
7. 02:22 PM - Re: Z-19 Function (Justin Jones)
8. 05:13 PM - Re: Z-19 Function (Robert L. Nuckolls, III)
9. 05:22 PM - Re: Real life lessons in wire ratings . . . (Robert L. Nuckolls, III)
10. 05:30 PM - Re: Z-19 Function (Justin Jones)
Message 1
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Subject: | Re: Dynon D-180 & flickering LEDs |
At 09:51 PM 8/18/2014, you wrote:
I have been corresponding with a RV-12 owner in TX. His Dynon D-180
has a problem with LEDs that flicker when they should be on
steady. The D-180 supplies negative PWM voltage to LEDs which are
external to the D-180. Download the D-180 Installation Manual
http://www.dynonavionics.com/downloads/Install_Guides/FlightDEK-D180_Installation_Guide_Rev_H.pdf
and read about "External EMS Warning Light" on page 4-10. The
aircraft owner did some experiments. Here are the results:
With the engine off and the D-180 powered by the aircraft battery,
the LEDs are on steady. With the engine running, the LEDs
flicker. With the engine still running, if the avionics switch is
shut off, the D-180 reverts to its internal backup battery and the
LEDs illuminate steadily. Engine still running and the avionics
switch is turned back on, the LEDs flicker again. This experiment
was repeated and the results are consistent. From these experiments
I conclude that the D-180 puts out a steady PWM voltage when
operating on battery power (whether aircraft battery or internal
backup battery). And when operating off the alternator, the D-180
puts out an intermittent PWM voltage which causes LED flicker.
Do I presume correctly that he has gone through the set up screen for
managing the output of this pin?
To configure EMS DB37 Pin 29 as an external warning light, enter the
EMS menu by pressing any button beneath an EMS main page. Press
MORE > SETUP > GLOBAL. Press DOWN. to select ALARM CONFIG and press
SEL. LGT BHVR: ACK SOLID configures the external alarm light to
remain on (solid) when the alarm condition is acknowledged. LGT BHVR:
ACK CLEAR configures the external alarm light to go off when the
alarm condition is acknowledged.
The word 'flicker' implies a visible, random modulation
of the light output. If this output is being deliberately
PWM for the purpose of controlling apparent intensity, the
PWM frequency will be too high for the eye to perceive anything
like a 'flicker' . . . it seems unlikely that the difficulty
is a function of any normal behaviors designed into the
D-180.
With the engine running, the D-180 indicates a system voltage of 13.7
which is normal for RV-12s. All E-LSA RV-12s have a 22,000
microfarad capacitor connected to the output of the Rotax
rectifier/regualtor. If that capacitor is bad, could that cause the
D-180 to output an unsteady PWM voltage to the the LEDs? Or should
the D-180 be able to function even if the aircraft electrical power
is dirty and not pure DC?
If you put a 'scope on the bus of any airplane with
the alternator running you will find that it's anything
but "pure DC". Mil-Std-704/DO-160 design and qualification
recommendations advise system integrators to consider this in
the design of bus-powered products. Dynon is no
less aware of this than anyone else . . . and based on
my conversations with them, perhaps more so.
The legacy 22,000 uF capacitor installation on PM alternators
is of limited utility for smoothing the output from
PM alternator rectifier/regulators. Peek at the bus with
a 'scope and do a capacitor-connected/disconnected comparison
for confirmation. A casual observation with a 'scope will
not produce much confidence that the capacitor is doing
anything useful in the time domain.
See: http://tinyurl.com/n5yd3vw
Some day I may get the chance to put a spectrum analyzer
on the bus and get some details for benefits in the
frequency domain . . . but I don't expect to see
anything that would alter the way we do system integration
under 704/160 design goals.
I suggest that he experiment with an incandescent lamp
wired to this output and powered from a couple of lantern
batteries or line operated bench supply. Then hook the
lamp to the bus for power to see if behavior changes.
He could also consider talking to the folks who designed
and built the system. They're very amiable folks (at least
they were the last time I talked with them perhaps 4 years
ago). They're going to know more about their system than
anyone you're going to find on this List . . . or in-the-wild.
Bob . . .
Message 2
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Subject: | PM alternator capacitors . . . |
The legacy 22,000 uF capacitor installation on PM alternators
is of limited utility for smoothing the output from
PM alternator rectifier/regulators. Peek at the bus with
a 'scope and do a capacitor-connected/disconnected comparison
for confirmation. A casual observation with a 'scope will
not produce much confidence that the capacitor is doing
anything useful in the time domain.
See: http://tinyurl.com/n5yd3vw
=======================
I was asked about the significance of the data cited
above . . . and I beg your indulgence . . . it's
not immediately obvious.
I've re-posted the data package and encircled
the pertinent data points: RMS and peak-to-peak
voltage numbers cited at the edge of the 'scope
screen.
These Pk-Pk values speak to the greatest voltage excursions
detected in the displayed plot . . . you can have some
pretty high numbers here if the wave form shows even
the shortest of 'spikes' . . . pk-to-pk numbers are
not terribly significant in these plots. RMS speaks
to the ENERGY in the noise.
Note that for ALL conditions measured, there are
no gross variations in measured noise configurations
of capacitor size and whether or not a battery is
on line. All measured values were well under those
we are told to expect on the legacy 704/160 realm
of DC power systems.
Publication of this data is not intended to
say that there is no value for including a
capacitor . . . but the published narratives
don't speak to any rationale other than noise
mitigation. It may be that some clever designer
perceived an improvement in performance for
something other than noise. If so, I'm unaware of it.
Bob . . .
Message 3
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Subject: | Re: Z-19 Function |
At 12:36 PM 8/18/2014, you wrote:
>Bob,
>
>I appreciate your help and opinion with this matter. I will
>approach Robert about this and find out the specifics of the
>electrical demands of his system. I have heard great things about
>his customer service and the folks using his system in their running
>aircraft have nothing but great things to say about it and him. He
>is a very knowledgable A&P and has deep knowledge of his system.
>
>Thank you again.
>
>Justin
Is there a real wiring diagram for this system? The manual
speaks to the need for 4 breakers in a dual ECU system
but I find only references to ECU power connections in
the harness picture. Do I have all the documentation
for this system?
Bob . . .
Message 4
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Subject: | Real life lessons in wire ratings . . . |
And don't even think of operating a welding machine on a coiled up extension
line.. J
Different story: Volt drop when pulling high current seriously deteriorates
performance; on a construction site that I was working on our sub
contracting welding team strung out 100+m (around 300') of 2.5mm2 cable
(roughly 13 AWG) and tried to weld (using a single phase hand carried
machine) on that. They kept tripping the supply transformer and annoying
everyone connected to it- through a number of faults that the protection
devices were observing; exactly what I don't know as I was busy with
something else and couldn't investigate, but from the timing clearly they
were the ones doing it. 'For some reason' they couldn't get the weld
quality they needed, and the power kept tripping. J
>From what I could reason the huge volt drop across the cable, created by the
long length and the small cross sectional area (and hence greater impedance)
caused the welder to draw more current; cable heats up, creating more
resistance, more volt drop, more current draw- more current; cable heats
up, creating more resistance, more volt drop, more current draw and so it
goes on.
Long wires require careful attention..
Johannesburg Jay
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: 19 August 2014 04:43 AM
Subject: AeroElectric-List: Real life lessons in wire ratings . . .
Last weekend, Dr. Dee and I spent Friday/Saturday
supporting our son's shaved ice and cotton candy
business during "Old Settlers Days" in Mulvane, KS.
Temperature in upper 90s. Shaved ice trailer with
lights, rooftop a/c, freezer and shaved ice machine
running on ac mains through 100', 12AWG extension
cord not unlike that pictured below. Total current
draw on the order of 13 amps.
Emacs!
Approximately 70' of cord was spooled out leaving about
30' still coiled on the reel. After 3 or 4 hours operation,
a vendor on the row behind us asked if that 'smoke and
bad smell' was something to be concerned about.
I swapped out the smoking cord for a spare.
I un-spooled the rest of the cord and discovered that
when not allowed the benefits of cooling air, the wrapped
up coils got pretty hot. The cord that was spooled out
was warmer than ambient but not markedly so. Voltage
at plug end under load was 124 volts . . . inside trailer
it was 117 volts for a round trip drop of about 7 volts.
Nonetheless, insulation on the poorly cooled wires
inside the yellow jacket fused together. In some places
the yellow jacket was breached and/or fused to adjacent
turns.
This cord reel is designed to encourage rolling out only
that cordage which is needed . . . but if you're going
to load it to near max ratings, then it's a good idea
to un-spool the entire length.
A profound demonstration of how temp rise on
a wire is exacerbated by constriction of free air cooling.
I cut off the damaged 30', installed a new plug and
left the full in-service length of cord laid out on
the ground for the rest of the event. Voltage drop
went down to just over 5 volts on the shortened cord.
Bob . . .
Message 5
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Subject: | Real life lessons in wire ratings . . . |
And don't even think of operating a welding machine on a coiled up extension
line.. J
Different story: Volt drop when pulling high current seriously deteriorates
performance; on a construction site that I was working on our sub
contracting welding team strung out 100+m (around 300') of 2.5mm2 cable
(roughly 13 AWG) and tried to weld (using a single phase hand carried
machine) on that. They kept tripping the supply transformer and annoying
everyone connected to it- through a number of faults that the protection
devices were observing; exactly what I don't know as I was busy with
something else and couldn't investigate, but from the timing clearly they
were the ones doing it. 'For some reason' they couldn't get the weld
quality they needed, and the power kept tripping. J
>From what I could reason the huge volt drop across the cable, created by the
long length and the small cross sectional area (and hence greater impedance)
caused the welder to draw more current; cable heats up, creating more
resistance, more volt drop, more current draw- more current; cable heats
up, creating more resistance, more volt drop, more current draw and so it
goes on.
Long wires require careful attention..
Johannesburg Jay
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: 19 August 2014 04:43 AM
Subject: AeroElectric-List: Real life lessons in wire ratings . . .
Last weekend, Dr. Dee and I spent Friday/Saturday
supporting our son's shaved ice and cotton candy
business during "Old Settlers Days" in Mulvane, KS.
Temperature in upper 90s. Shaved ice trailer with
lights, rooftop a/c, freezer and shaved ice machine
running on ac mains through 100', 12AWG extension
cord not unlike that pictured below. Total current
draw on the order of 13 amps.
Emacs!
Approximately 70' of cord was spooled out leaving about
30' still coiled on the reel. After 3 or 4 hours operation,
a vendor on the row behind us asked if that 'smoke and
bad smell' was something to be concerned about.
I swapped out the smoking cord for a spare.
I un-spooled the rest of the cord and discovered that
when not allowed the benefits of cooling air, the wrapped
up coils got pretty hot. The cord that was spooled out
was warmer than ambient but not markedly so. Voltage
at plug end under load was 124 volts . . . inside trailer
it was 117 volts for a round trip drop of about 7 volts.
Nonetheless, insulation on the poorly cooled wires
inside the yellow jacket fused together. In some places
the yellow jacket was breached and/or fused to adjacent
turns.
This cord reel is designed to encourage rolling out only
that cordage which is needed . . . but if you're going
to load it to near max ratings, then it's a good idea
to un-spool the entire length.
A profound demonstration of how temp rise on
a wire is exacerbated by constriction of free air cooling.
I cut off the damaged 30', installed a new plug and
left the full in-service length of cord laid out on
the ground for the rest of the event. Voltage drop
went down to just over 5 volts on the shortened cord.
Bob . . .
Message 6
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Subject: | Re: Real life lessons in wire ratings . . . |
Was the insulation on the individual conductors compromised? Was there
any indication that there was the threat of an actual short occurring or
was it just a matter of the outer jacket melting?
Who was the manufacturer and/or what brand name was the cord sold under?
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty,
understanding and feeling are the concomitants of failure in our system.
And those traits we detest, sharpness, greed, acquisitiveness, meanness,
egotism and self-interest are the traits of success. And while men
admire the quality of the first they love the produce of the second.
-John Steinbeck, novelist, Nobel laureate (1902-1968)
On 08/18/2014 09:43 PM, Robert L. Nuckolls, III wrote:
> Last weekend, Dr. Dee and I spent Friday/Saturday
> supporting our son's shaved ice and cotton candy
> business during "Old Settlers Days" in Mulvane, KS.
>
> Temperature in upper 90s. Shaved ice trailer with
> lights, rooftop a/c, freezer and shaved ice machine
> running on ac mains through 100', 12AWG extension
> cord not unlike that pictured below. Total current
> draw on the order of 13 amps.
>
> Emacs!
> Approximately 70' of cord was spooled out leaving about
> 30' still coiled on the reel. After 3 or 4 hours operation,
> a vendor on the row behind us asked if that 'smoke and
> bad smell' was something to be concerned about.
>
> I swapped out the smoking cord for a spare.
>
> I un-spooled the rest of the cord and discovered that
> when not allowed the benefits of cooling air, the wrapped
> up coils got pretty hot. The cord that was spooled out
> was warmer than ambient but not markedly so. Voltage
> at plug end under load was 124 volts . . . inside trailer
> it was 117 volts for a round trip drop of about 7 volts.
>
> Nonetheless, insulation on the poorly cooled wires
> inside the yellow jacket fused together. In some places
> the yellow jacket was breached and/or fused to adjacent
> turns.
>
> This cord reel is designed to encourage rolling out only
> that cordage which is needed . . . but if you're going
> to load it to near max ratings, then it's a good idea
> to un-spool the entire length.
>
> A profound demonstration of how temp rise on
> a wire is exacerbated by constriction of free air cooling.
> I cut off the damaged 30', installed a new plug and
> left the full in-service length of cord laid out on
> the ground for the rest of the event. Voltage drop
> went down to just over 5 volts on the shortened cord.
>
> Bob . . .
>
Message 7
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Subject: | Re: Z-19 Function |
Bob,
I just sent the request for the diagram to Robert. I will forward it
along as soon as it comes in.
Thanks
Justin
On Aug 19, 2014, at 11:16 AM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
> At 12:36 PM 8/18/2014, you wrote:
>> Bob,
>>
>> I appreciate your help and opinion with this matter. I will approach
Robert about this and find out the specifics of the electrical demands
of his system. I have heard great things about his customer service and
the folks using his system in their running aircraft have nothing but
great things to say about it and him. He is a very knowledgable A&P and
has deep knowledge of his system.
>>
>> Thank you again.
>>
>> Justin
>
> Is there a real wiring diagram for this system? The manual
> speaks to the need for 4 breakers in a dual ECU system
> but I find only references to ECU power connections in
> the harness picture. Do I have all the documentation
> for this system?
>
>
> Bob . . .
>
>
>
>
Message 8
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Subject: | Re: Z-19 Function |
At 04:21 PM 8/19/2014, you wrote:
>Bob,
>
>I just sent the request for the diagram to Robert. I will forward
>it along as soon as it comes in.
So I take it that you were expected to install this
system with no wiring diagram?
Bob . . .
Message 9
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Subject: | Re: Real life lessons in wire ratings . . . |
At 02:58 PM 8/19/2014, you wrote:
>
>Was the insulation on the individual conductors compromised? Was
>there any indication that there was the threat of an actual short
>occurring or was it just a matter of the outer jacket melting?
No, all levels of insulation was being deformed.
Temperatures were high enough to cause visible
smoke. No short before it was unplugged.
>Who was the manufacturer and/or what brand name was the cord sold under?
It's not a NEMA graded cordage but no reason to
believe it's not adequate to the ratings common to
the wire (12AWG). The portions that were laying
out on the ground were 'happy' . . . only those
turns deprived of opan-air cooling got into
trouble. Wire bundles in airplane will do the same
thing.
Emacs!
Here's a piece of 22759, 10AWG in a bundle
'protected' by silicone impregnated fiberglas
transiting a hot environment. Got hot enough
for the Tefzel wrap to separate at edge bond.
Bob . . .
Message 10
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Subject: | Re: Z-19 Function |
I have just the installation instructions at this time. Not sure if I have ever
seen a wiring diagram for it.
Justin
On Aug 19, 2014, at 4:08 PM, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
>
> At 04:21 PM 8/19/2014, you wrote:
>> Bob,
>>
>> I just sent the request for the diagram to Robert. I will forward it along
as soon as it comes in.
>
> So I take it that you were expected to install this
> system with no wiring diagram?
>
>
>
> Bob . . .
>
>
>
>
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