Today's Message Index:
----------------------
1. 07:52 AM - Fw: Fw: LVWM and Kilovac contactors (Gilles Thesee)
2. 08:21 AM - Re: Re: Load Dump mitigation (Paul Messinger)
3. 09:01 AM - Re: Re: Load Dump mitigation (George Braly)
4. 09:22 AM - Digital Photos (Chuck Jensen)
5. 09:57 AM - Re: Re: Load Dump mitigation (George Braly)
6. 09:59 AM - Re: Digital Photos (Matt Prather)
7. 11:42 AM - Re: Digital Photos (Rick Girard)
8. 01:32 PM - Re: Load Dump mitigation (Eric M. Jones)
9. 07:32 PM - Re: Re: Load Dump mitigation (Richard Sipp)
10. 08:37 PM - Re: Re: Load Dump mitigation (George Braly)
11. 08:55 PM - Re: Ideas on painting panel? (Greg.Puckett@united.com)
Message 1
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| Subject: | LVWM and Kilovac contactors |
--> AeroElectric-List message posted by: "Gilles Thesee" <Gilles.Thesee@ac-grenoble.fr>
Bob,
Maybe my recent post got through unnoticed.
I'd welcome any hints as to how I could cure or work around the problem.
Any suggestion ?
Thanks,
Gilles
----- Original Message -----
From: "Gilles Thesee" <Gilles.Thesee@ac-grenoble.fr>
Subject: Re: Fw: AeroElectric-List: LVWM and Kilovac contactors
> --> AeroElectric-List message posted by: "Gilles Thesee"
> <Gilles.Thesee@ac-grenoble.fr>
>
> Hi Bob and all,
>
> In order to pinpoint the origin of my problem with the LVWM and the
> Kilovac
> contactors I tried four different models of relays. I ended with a
> transparent case relay which revealed the problem is not with the relay.
> After extensive tests I've come to the conclusion it may be the
> association
> of the LVWM with the Kilovac contactors. For some reasons when the Kilovac
> contactors are energized they seem to somehow disturb something inside the
> LVWM.
> More details can be found at the following URL :
>
> http://gilles.thesee.free.fr/Elec_architecture.htm
>
> At the moment we still can perform the flight tests but I would really
> appreciate any help or workaround. In effect the LVWM is the only
> practical
> means of informing the pilot that something may be wrong with the
> auxiliary
> battery. And wih our electrically dependant engine this aux battery is the
> last resort if the alternator quits.
>
> Thanks for your help,
> Best wishes for 2005
>
> Gilles
Message 2
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I remember your comments about this when this issue first started early last
year.
Because I value your comments and experience highly, we need to look into
your experience further as it would appear there is something going on that
is not apparent in my testing and that testing was reviewed by my partner
and 6 other experts. This in no way is to suggest I question your results,
just we need to look further to see what is being missed. Perhaps it unique
to a specific alternator ?? ; what ever it does need investigation.
Both the ST load dump transorb and the 5K device I have tested are above the
load dump energies mfgrs spec for protection.
I was unable to damage even a single 1.5K 18V device (but it was
overstressed based on Observed junction overheating and the estimated energy
vs the data sheet max.) with a 50 amp load dump with the alternator I was
using which was a 60 amp unit from a Subaru EA81 designed and sold in Japan.
The residual alternator load was 1 amp and 1000 MFD to smooth the pulse for
data recording. I would be very interested in the exact conditions where you
were able to destroy 5K devices.
I did test using a 25,000 mfd capacitor with no battery and keeping the
alternator on line to the system load of 10 amps and the above 25,000 mfd
cap and the test 40 amp load dump was controlled with the above remaining on
the buss.
Basically the B lead was connected to the mockup electrical system with a
total load of 50 amps. The alternator side of the alternator B lead
contactor had the 10 amp load and the 25,000 mfd cap. NO Transorb. The 40
amp load was then removed creating a load dump of 40 amps.
This was part of the testing where the possibiliy of no battery operation
was investigated. The bus voltage was controlled by the cap but not all that
well and much higher than desired. My conclusion was that even 25,000 mfd
was insufficent to stabilize the system buss with no battery. Even 10 amp
load dumps like landing lights being turned off caused the system bus to
exceed 16V where the common OVP protection kicks in. In any case the common
OVP circuit would have prevented no battery operation as a resonable size
capacitor to stabilize the buss will not stabilize it enough..
Paul
----- Original Message -----
From: "George Braly" <gwbraly@gami.com>
Subject: RE: AeroElectric-List: Re: Load Dump mitigation
> --> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>
>
> Bob,
>
> With the battery off line, I have repeatedly been able to destroy 5KP18
devices with load dumps from 40 amp alternators on 14 volt systems.
>
> In my experience, nothing short of a very active and robust OV clamp
circuit, with lots of capacitance also on line, is sufficient to prevent
the destruction of the 5KP18 devices - - - in which case those devices
become unnecessary.
>
> Regards, George
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Re: Load Dump mitigation
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<b.nuckolls@cox.net>
>
> At 11:44 AM 1/4/2005 -0600, you wrote:
>
> >--> AeroElectric-List message posted by: Jerzy Krasinski
> ><krasinski@provalue.net>
> >
> >Bob,
> >
> >I wonder why did you select 5KP18 which begins to sink current (5mA) at
> >a voltage of approximately 21V? Is such a big voltage margin necessary?
> >
> >5KP14 opens at a voltage of approximately 16V which seems to be
> >sufficiently higher than the battery voltage, and hopefully it would
> >clamp the output to a lower peak voltage.
>
> Why would one wish to select a lower voltage?
>
> >Did you manage to find voltage versus current curves for these diodes?
> >How much voltage do we get accross the diode at the rated peak surge
> >current of 400A?
>
>
> Only the point data charts that are offered by the manufacturers.
> You're never going to see 400A . . . the MOST you can ever
> see is the alternator's maximum capability.
>
> During a REAL ov condition, you want enough headroom between
> onset of load-dump mitigation and the reaction time of an
> OV protection system so that you don't pop the Transorb. I
> selected the 5KP18 as likely to stay out of the OV protection
> loop while meeting the need to limit load-dump transients
> to levels well inside DO-160 recommendations.
>
> Keep in mind also that we're probably only concerned with
> alternators having after-market regulators in them. I cannot
> imagine that a modern alternator manufacturer will not account
> for the load dump transient in design and selection of components
> in their regulators. It would be interesting to see the pedigree
> on regulators that failed when the alternator was unloaded in
> a Figure Z-24 configuration.
>
> The important data point from Paul's experiments is that
> load dump energies are quite low. I suspected this given the
> relative sizes of components offered specifically for the
> purpose of standing off alternator load-dump events. I'm negotiating
> for a used alternator test stand and should be able to refine
> the data base next spring (my garage shop isn't heated). In
> the mean time, I'm reasonably certain that adding the 5KP18
> will mitigate the problems cited by Van's builders.
>
> Others may have different criteria for selecting lower targets
> for peak voltage but I'm comfortable with DO-160 recommendations.
> I've not found it difficult to work within those bounds for 35
> years or so. A part recommended for 14V load dump mitigation
> was discussed on this list some months ago. It's the
ST-MicroElectronics
> LDP24A which has a threshold voltage of 24 volts and clamps
> a 30A dump at about 40 volts. The 5KP18 will clamp a 100A
> dump to some value less than 30 volts . . . quite comfortably
> inside the limits of DO-160 and plenty of headroom for
> OV protection to do its job independently from the
> load-dump protection.
>
> Bob . . .
>
>
> ---
>
>
> ---
>
>
Message 3
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
I am leaving for an appointment. More later. In the mean time.
It was a Denso 40 amp alternator core, at 4000 shaft rpm, into landing light loads,
which were switched "off". Residual load was less than 1 amp.
There was only about 10MFD of capacitance on the system.
It would fry otherwise modestly protected 5 volt power supplies also on the same
buss, as well as the transorbs.
Regards, George
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul Messinger
Subject: Re: AeroElectric-List: Re: Load Dump mitigation
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I remember your comments about this when this issue first started early last
year.
Because I value your comments and experience highly, we need to look into
your experience further as it would appear there is something going on that
is not apparent in my testing and that testing was reviewed by my partner
and 6 other experts. This in no way is to suggest I question your results,
just we need to look further to see what is being missed. Perhaps it unique
to a specific alternator ?? ; what ever it does need investigation.
Both the ST load dump transorb and the 5K device I have tested are above the
load dump energies mfgrs spec for protection.
I was unable to damage even a single 1.5K 18V device (but it was
overstressed based on Observed junction overheating and the estimated energy
vs the data sheet max.) with a 50 amp load dump with the alternator I was
using which was a 60 amp unit from a Subaru EA81 designed and sold in Japan.
The residual alternator load was 1 amp and 1000 MFD to smooth the pulse for
data recording. I would be very interested in the exact conditions where you
were able to destroy 5K devices.
I did test using a 25,000 mfd capacitor with no battery and keeping the
alternator on line to the system load of 10 amps and the above 25,000 mfd
cap and the test 40 amp load dump was controlled with the above remaining on
the buss.
Basically the B lead was connected to the mockup electrical system with a
total load of 50 amps. The alternator side of the alternator B lead
contactor had the 10 amp load and the 25,000 mfd cap. NO Transorb. The 40
amp load was then removed creating a load dump of 40 amps.
This was part of the testing where the possibiliy of no battery operation
was investigated. The bus voltage was controlled by the cap but not all that
well and much higher than desired. My conclusion was that even 25,000 mfd
was insufficent to stabilize the system buss with no battery. Even 10 amp
load dumps like landing lights being turned off caused the system bus to
exceed 16V where the common OVP protection kicks in. In any case the common
OVP circuit would have prevented no battery operation as a resonable size
capacitor to stabilize the buss will not stabilize it enough..
Paul
----- Original Message -----
From: "George Braly" <gwbraly@gami.com>
Subject: RE: AeroElectric-List: Re: Load Dump mitigation
> --> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>
>
> Bob,
>
> With the battery off line, I have repeatedly been able to destroy 5KP18
devices with load dumps from 40 amp alternators on 14 volt systems.
>
> In my experience, nothing short of a very active and robust OV clamp
circuit, with lots of capacitance also on line, is sufficient to prevent
the destruction of the 5KP18 devices - - - in which case those devices
become unnecessary.
>
> Regards, George
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Re: Load Dump mitigation
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<b.nuckolls@cox.net>
>
> At 11:44 AM 1/4/2005 -0600, you wrote:
>
> >--> AeroElectric-List message posted by: Jerzy Krasinski
> ><krasinski@provalue.net>
> >
> >Bob,
> >
> >I wonder why did you select 5KP18 which begins to sink current (5mA) at
> >a voltage of approximately 21V? Is such a big voltage margin necessary?
> >
> >5KP14 opens at a voltage of approximately 16V which seems to be
> >sufficiently higher than the battery voltage, and hopefully it would
> >clamp the output to a lower peak voltage.
>
> Why would one wish to select a lower voltage?
>
> >Did you manage to find voltage versus current curves for these diodes?
> >How much voltage do we get accross the diode at the rated peak surge
> >current of 400A?
>
>
> Only the point data charts that are offered by the manufacturers.
> You're never going to see 400A . . . the MOST you can ever
> see is the alternator's maximum capability.
>
> During a REAL ov condition, you want enough headroom between
> onset of load-dump mitigation and the reaction time of an
> OV protection system so that you don't pop the Transorb. I
> selected the 5KP18 as likely to stay out of the OV protection
> loop while meeting the need to limit load-dump transients
> to levels well inside DO-160 recommendations.
>
> Keep in mind also that we're probably only concerned with
> alternators having after-market regulators in them. I cannot
> imagine that a modern alternator manufacturer will not account
> for the load dump transient in design and selection of components
> in their regulators. It would be interesting to see the pedigree
> on regulators that failed when the alternator was unloaded in
> a Figure Z-24 configuration.
>
> The important data point from Paul's experiments is that
> load dump energies are quite low. I suspected this given the
> relative sizes of components offered specifically for the
> purpose of standing off alternator load-dump events. I'm negotiating
> for a used alternator test stand and should be able to refine
> the data base next spring (my garage shop isn't heated). In
> the mean time, I'm reasonably certain that adding the 5KP18
> will mitigate the problems cited by Van's builders.
>
> Others may have different criteria for selecting lower targets
> for peak voltage but I'm comfortable with DO-160 recommendations.
> I've not found it difficult to work within those bounds for 35
> years or so. A part recommended for 14V load dump mitigation
> was discussed on this list some months ago. It's the
ST-MicroElectronics
> LDP24A which has a threshold voltage of 24 volts and clamps
> a 30A dump at about 40 volts. The 5KP18 will clamp a 100A
> dump to some value less than 30 volts . . . quite comfortably
> inside the limits of DO-160 and plenty of headroom for
> OV protection to do its job independently from the
> load-dump protection.
>
> Bob . . .
>
>
> ---
>
>
> ---
>
>
---
---
Message 4
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--> AeroElectric-List message posted by: Chuck Jensen <cjensen@dts9000.com>
Bob,
What do you use for camera/lense and any special settings for the photos you
provide. We (at least me) would appreciate some clues on how to get
digitals with the same sharpness and fine detail.
Thanks
Chuck
Message 5
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
Sorry... 10K mfd capacitance on the system... not 10mfd.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of George Braly
Subject: RE: AeroElectric-List: Re: Load Dump mitigation
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
I am leaving for an appointment. More later. In the mean time.
It was a Denso 40 amp alternator core, at 4000 shaft rpm, into landing light loads,
which were switched "off". Residual load was less than 1 amp.
There was only about 10MFD of capacitance on the system.
It would fry otherwise modestly protected 5 volt power supplies also on the same
buss, as well as the transorbs.
Regards, George
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul Messinger
Subject: Re: AeroElectric-List: Re: Load Dump mitigation
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I remember your comments about this when this issue first started early last
year.
Because I value your comments and experience highly, we need to look into
your experience further as it would appear there is something going on that
is not apparent in my testing and that testing was reviewed by my partner
and 6 other experts. This in no way is to suggest I question your results,
just we need to look further to see what is being missed. Perhaps it unique
to a specific alternator ?? ; what ever it does need investigation.
Both the ST load dump transorb and the 5K device I have tested are above the
load dump energies mfgrs spec for protection.
I was unable to damage even a single 1.5K 18V device (but it was
overstressed based on Observed junction overheating and the estimated energy
vs the data sheet max.) with a 50 amp load dump with the alternator I was
using which was a 60 amp unit from a Subaru EA81 designed and sold in Japan.
The residual alternator load was 1 amp and 1000 MFD to smooth the pulse for
data recording. I would be very interested in the exact conditions where you
were able to destroy 5K devices.
I did test using a 25,000 mfd capacitor with no battery and keeping the
alternator on line to the system load of 10 amps and the above 25,000 mfd
cap and the test 40 amp load dump was controlled with the above remaining on
the buss.
Basically the B lead was connected to the mockup electrical system with a
total load of 50 amps. The alternator side of the alternator B lead
contactor had the 10 amp load and the 25,000 mfd cap. NO Transorb. The 40
amp load was then removed creating a load dump of 40 amps.
This was part of the testing where the possibiliy of no battery operation
was investigated. The bus voltage was controlled by the cap but not all that
well and much higher than desired. My conclusion was that even 25,000 mfd
was insufficent to stabilize the system buss with no battery. Even 10 amp
load dumps like landing lights being turned off caused the system bus to
exceed 16V where the common OVP protection kicks in. In any case the common
OVP circuit would have prevented no battery operation as a resonable size
capacitor to stabilize the buss will not stabilize it enough..
Paul
----- Original Message -----
From: "George Braly" <gwbraly@gami.com>
Subject: RE: AeroElectric-List: Re: Load Dump mitigation
> --> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>
>
> Bob,
>
> With the battery off line, I have repeatedly been able to destroy 5KP18
devices with load dumps from 40 amp alternators on 14 volt systems.
>
> In my experience, nothing short of a very active and robust OV clamp
circuit, with lots of capacitance also on line, is sufficient to prevent
the destruction of the 5KP18 devices - - - in which case those devices
become unnecessary.
>
> Regards, George
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Re: Load Dump mitigation
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<b.nuckolls@cox.net>
>
> At 11:44 AM 1/4/2005 -0600, you wrote:
>
> >--> AeroElectric-List message posted by: Jerzy Krasinski
> ><krasinski@provalue.net>
> >
> >Bob,
> >
> >I wonder why did you select 5KP18 which begins to sink current (5mA) at
> >a voltage of approximately 21V? Is such a big voltage margin necessary?
> >
> >5KP14 opens at a voltage of approximately 16V which seems to be
> >sufficiently higher than the battery voltage, and hopefully it would
> >clamp the output to a lower peak voltage.
>
> Why would one wish to select a lower voltage?
>
> >Did you manage to find voltage versus current curves for these diodes?
> >How much voltage do we get accross the diode at the rated peak surge
> >current of 400A?
>
>
> Only the point data charts that are offered by the manufacturers.
> You're never going to see 400A . . . the MOST you can ever
> see is the alternator's maximum capability.
>
> During a REAL ov condition, you want enough headroom between
> onset of load-dump mitigation and the reaction time of an
> OV protection system so that you don't pop the Transorb. I
> selected the 5KP18 as likely to stay out of the OV protection
> loop while meeting the need to limit load-dump transients
> to levels well inside DO-160 recommendations.
>
> Keep in mind also that we're probably only concerned with
> alternators having after-market regulators in them. I cannot
> imagine that a modern alternator manufacturer will not account
> for the load dump transient in design and selection of components
> in their regulators. It would be interesting to see the pedigree
> on regulators that failed when the alternator was unloaded in
> a Figure Z-24 configuration.
>
> The important data point from Paul's experiments is that
> load dump energies are quite low. I suspected this given the
> relative sizes of components offered specifically for the
> purpose of standing off alternator load-dump events. I'm negotiating
> for a used alternator test stand and should be able to refine
> the data base next spring (my garage shop isn't heated). In
> the mean time, I'm reasonably certain that adding the 5KP18
> will mitigate the problems cited by Van's builders.
>
> Others may have different criteria for selecting lower targets
> for peak voltage but I'm comfortable with DO-160 recommendations.
> I've not found it difficult to work within those bounds for 35
> years or so. A part recommended for 14V load dump mitigation
> was discussed on this list some months ago. It's the
ST-MicroElectronics
> LDP24A which has a threshold voltage of 24 volts and clamps
> a 30A dump at about 40 volts. The 5KP18 will clamp a 100A
> dump to some value less than 30 volts . . . quite comfortably
> inside the limits of DO-160 and plenty of headroom for
> OV protection to do its job independently from the
> load-dump protection.
>
> Bob . . .
>
>
> ---
>
>
> ---
>
>
---
---
---
---
Message 6
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| Subject: | Re: Digital Photos |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
I have had good luck using the 'macro' feature that my Canon
A80 has. Here's a link to a picture of a camlock that I took for
a buddy of mine:
http://www.webpak.net/~mprather/Airplanes/Share/040314%20023_crop.JPG
Make sure you get the whole link...
I took this with the camlock sitting in the sun on the concrete
hangar floor.
Regards,
Matt-
> --> AeroElectric-List message posted by: Chuck Jensen
> <cjensen@dts9000.com>
>
> Bob,
>
> What do you use for camera/lense and any special settings for the photos
> you provide. We (at least me) would appreciate some clues on how to get
> digitals with the same sharpness and fine detail.
>
> Thanks
> Chuck
>
>
Message 7
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| Subject: | Re: Digital Photos |
--> AeroElectric-List message posted by: Rick Girard <fly.ez@verizon.net>
Having just splurged an a digital camera in the after Christmas frenzy,
let me share a few things I learned.
1. For web postings and most photo usage, 3 Mpixels will do quite nicely.
2. Make sure the camera has a USB cord. Windows XP's camera wizard will
let you download directly to your computer without special software.
3. Check the type of memory card the camera uses. At the time I
purchased, Sd chips were the cheapest. I was able to get 4 times the
memory for less than half the price of Xd memory. The more memory, the
more pictures you can take. With 512 Mbytes, I can take 250 pictures at
the highest density setting.
4. Some cameras have plastic lenses, some have glass. My personal
preference is for glass.
5. While I like rechargeable batteries, I bought one that uses alkalines
and has the option of several rechargeables. Nothing will upset me as
much as getting the low battery signal while in the field and having no
way to recharge.
6. Whatever camera you buy, download a copy of Irfanview. It's free and
is an amazingly easy to use photo editor. It has more features than
either of the software that came with my cameras (I have a video cam
that takes low resolution digital stills, which is how I learned about
what I wanted in a still digital camera)
7. If you decide to buy off the web, get a guarantee that they have the
camera in stock. Some dealers are stocking dealers, some are drop
shippers who wait to get enough orders to submit. My friend got screwed
around for over a month while they had his money. I found when all
things were taken into account, one of the big electronics stores was
only a few dollars more than the web stores and they could put it in my
hand as they took my money.
Good Luck,
Rick Girard
LongEZ builder and very happy Nikon Coolpix owner
Message 8
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
> With the battery off line, I have repeatedly been able to destroy 5KP18
>devices with load dumps from 40 amp alternators on 14 volt systems.
>
> Regards, George
George....George....George....Something else is going on in your test setup
to blow the 5KP18's. A schematic and enough information to duplicate your
results would be appreciated.
Paul Messinger and I have been working on this for some time and I agree
with him that blowing up the 5KP18 seems impossible. There is one way it
might have happened--Zeners and Mosorbs and Transorbs have a very
(picosecond) short trip time. It would seem to be good practice to try by
component placement and very short lead lengths to keep the trip time very
short by minimizing lead inductance (thus length). Engineers familiar with
high frequencies would do this by second nature.
A small note in the 1N6267A-series On-Semi datasheet page 5, gives one
pause: "Some input impedance...is essential to prevent overstress of the
protection device. This impedance should be as high as possible, without
restricting the circuit operation."
Oops....! It is true that the initial discharge of capacitors, inductors,
batteries, static accumulations, etc. would be infinite were it not for lead
inductance (and a little internal resistance and stray capacitance...etc.).
So On Semiconductor says use the highest impedance that will still do the
job.
Paul and I and others have discussed the proper value for the Load Dump
Suppressor trip voltage. I was holding out for 22 volts but Paul convinced
me that it made no sense to go any higher than was absolutely necessary to
allow the other OVP devices to function. Since this OVP voltage seems to
be-- by consensus--16.2V, then 18V was entirely adequate. Why not...?
Nothing good happens by letting the voltage get higher.
I am now selling the WhackJack Load Dump Suppressor (18V) on my website that
will do the job. It uses three Mosorbs, since the oscilloscope shows a very
nice flattening of the Load Dump curve overshoot when using parallel
devices. The redundancy is nice too.
See: http://www.periheliondesign.com/whackjack18.htm
Paul has been a bit under the weather lately but I anxiously await the
finished Load Dump report.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"telegraph is a kind of a very, very long cat. You pull his tail in New
York
and his head meows in Los Angeles. And radio operates exactly the same way--
you send signals here, they receive them there. The only difference is that
there is no cat."
--Albert Einstein
Message 9
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "Richard Sipp" <rsipp@earthlink.net>
Eric:
I am impressed, as an electrical theory student still in 101 what you wrote
looks like a master's class and very interesting.
I know you have an interest in selling your WhackJacks (love the name) but
is there an operational technique that will also mitigate load dump; i.e.
with engine idling turn off all electronic loads, deactivate alternator
field, shut down engine.
Regards
Dick Sipp
RV4/RV10
----- Original Message -----
From: "Eric M. Jones" <emjones@charter.net>
Subject: AeroElectric-List: Re: Load Dump mitigation
> --> AeroElectric-List message posted by: "Eric M. Jones"
> <emjones@charter.net>
>
>
> --> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>> With the battery off line, I have repeatedly been able to destroy 5KP18
>>devices with load dumps from 40 amp alternators on 14 volt systems.
>>
>> Regards, George
>
> George....George....George....Something else is going on in your test
> setup
> to blow the 5KP18's. A schematic and enough information to duplicate your
> results would be appreciated.
>
> Paul Messinger and I have been working on this for some time and I agree
> with him that blowing up the 5KP18 seems impossible. There is one way it
> might have happened--Zeners and Mosorbs and Transorbs have a very
> (picosecond) short trip time. It would seem to be good practice to try by
> component placement and very short lead lengths to keep the trip time very
> short by minimizing lead inductance (thus length). Engineers familiar with
> high frequencies would do this by second nature.
>
> A small note in the 1N6267A-series On-Semi datasheet page 5, gives one
> pause: "Some input impedance...is essential to prevent overstress of the
> protection device. This impedance should be as high as possible, without
> restricting the circuit operation."
>
> Oops....! It is true that the initial discharge of capacitors, inductors,
> batteries, static accumulations, etc. would be infinite were it not for
> lead
> inductance (and a little internal resistance and stray
> capacitance...etc.).
> So On Semiconductor says use the highest impedance that will still do the
> job.
>
> Paul and I and others have discussed the proper value for the Load Dump
> Suppressor trip voltage. I was holding out for 22 volts but Paul convinced
> me that it made no sense to go any higher than was absolutely necessary to
> allow the other OVP devices to function. Since this OVP voltage seems to
> be-- by consensus--16.2V, then 18V was entirely adequate. Why not...?
> Nothing good happens by letting the voltage get higher.
>
> I am now selling the WhackJack Load Dump Suppressor (18V) on my website
> that
> will do the job. It uses three Mosorbs, since the oscilloscope shows a
> very
> nice flattening of the Load Dump curve overshoot when using parallel
> devices. The redundancy is nice too.
>
> See: http://www.periheliondesign.com/whackjack18.htm
>
> Paul has been a bit under the weather lately but I anxiously await the
> finished Load Dump report.
>
> Regards,
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge MA 01550-2705
> Phone (508) 764-2072
> Email: emjones@charter.net
>
> "telegraph is a kind of a very, very long cat. You pull his tail in New
> York
> and his head meows in Los Angeles. And radio operates exactly the same
> way--
> you send signals here, they receive them there. The only difference is
> that
> there is no cat."
> --Albert Einstein
>
>
>
Message 10
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| Subject: | Re: Load Dump mitigation |
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
I talked with Paul at some length today.
You are right, he is a sick puppy, right now.
Hope he gets better.
Eric, I'm not saying your device does not work. I don't know that. I assume
it works, just because you say it does and you do good work.
OTOH, I have blown a couple of dozen 1.5, and even 5K TVS devices of a variety
of different trip voltages.
They did not protect other components in the same system.
40amp alternator at 4000 rpm, into landing lights for a load.
Switch the landing lights off ... and ZAP... smoke comes out.
I tried several of them in various combinations in parallel --- more smoke.
That was my experience. After playing around trying to figure it out over a period
of a couple of months, I confessed defeat, and backed up and re-thought
the whole issue, and took a different approach that is relatively inexpensive,
straightforward, and works. Consistently.
Further, it is thermally protected so that it does not fail from overload.
It works so well that I made a flight a few weeks ago - - 2.5 hours, night, IMC
flight with nothing pumping electrons but the 40 AMP alternator - - the battery
and aircraft primary alternator were disabled. At the end of the flight,
I load dumped every thing in a real airplane with a real panel of expensive electronics.
Everything came back to life.
Regards, George
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M. Jones
Subject: AeroElectric-List: Re: Load Dump mitigation
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
> With the battery off line, I have repeatedly been able to destroy 5KP18
>devices with load dumps from 40 amp alternators on 14 volt systems.
>
> Regards, George
George....George....George....Something else is going on in your test setup
to blow the 5KP18's. A schematic and enough information to duplicate your
results would be appreciated.
Paul Messinger and I have been working on this for some time and I agree
with him that blowing up the 5KP18 seems impossible. There is one way it
might have happened--Zeners and Mosorbs and Transorbs have a very
(picosecond) short trip time. It would seem to be good practice to try by
component placement and very short lead lengths to keep the trip time very
short by minimizing lead inductance (thus length). Engineers familiar with
high frequencies would do this by second nature.
A small note in the 1N6267A-series On-Semi datasheet page 5, gives one
pause: "Some input impedance...is essential to prevent overstress of the
protection device. This impedance should be as high as possible, without
restricting the circuit operation."
Oops....! It is true that the initial discharge of capacitors, inductors,
batteries, static accumulations, etc. would be infinite were it not for lead
inductance (and a little internal resistance and stray capacitance...etc.).
So On Semiconductor says use the highest impedance that will still do the
job.
Paul and I and others have discussed the proper value for the Load Dump
Suppressor trip voltage. I was holding out for 22 volts but Paul convinced
me that it made no sense to go any higher than was absolutely necessary to
allow the other OVP devices to function. Since this OVP voltage seems to
be-- by consensus--16.2V, then 18V was entirely adequate. Why not...?
Nothing good happens by letting the voltage get higher.
I am now selling the WhackJack Load Dump Suppressor (18V) on my website that
will do the job. It uses three Mosorbs, since the oscilloscope shows a very
nice flattening of the Load Dump curve overshoot when using parallel
devices. The redundancy is nice too.
See: http://www.periheliondesign.com/whackjack18.htm
Paul has been a bit under the weather lately but I anxiously await the
finished Load Dump report.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"telegraph is a kind of a very, very long cat. You pull his tail in New
York
and his head meows in Los Angeles. And radio operates exactly the same way--
you send signals here, they receive them there. The only difference is that
there is no cat."
--Albert Einstein
---
---
Message 11
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| Subject: | Re: Ideas on painting panel? |
--> AeroElectric-List message posted by: Greg.Puckett@united.com
Ron,
I can't remember now who gave me this idea but I love the way it came
out.
http://204.31.68.69/DCP=5F252.JPG
It's black Krylon Wrinkle paint in a rattle can from Checker. I then
sprayed textured grey (or whatever color you want) over top.
It took many days to fully dry with the grey over the wrinkle finish but
when it finally did dry, the finish is extremely durable and absolutely
glare free.
I liked it on the panel so much I used only the black wrinkle paint on
the glare shield and it produced a very nice looking non reflecting
surface.
It takes a little practice and experimenting with temperature/coat
thickness/ and time between coats to get what you want. I found it a
little tough to do small items with this stuff but large areas were easy
to do.
Greg Puckett
Elizabeth, CO
In near future need to paint panel on Europa XS.
It has a fiberglass Instrument Module that will have 3 aluminium
inserts.
The fiberglass has an eyebrow for glare.
What suggestions on painting=3F Should the bottom of brow be very dark=3F I
imagine the top of the fiberglass does not want to be too dark so it
does
not heat up too much=3F
I imagine I want flat on instrument module and brow, what is preference
out
there for face of panel, light / dark flat or gloss=3F
What ideas for on type of paint to use.
Thx.
Sincerely
Ron Parigoris
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