Today's Message Index:
----------------------
1. 01:38 AM - Coil Suppression Techniques ()
2. 03:48 AM - Re: Coil Suppression Techniques (jetboy)
3. 06:18 AM - Re: Coil Suppression Techniques (Robert L. Nuckolls, III)
4. 06:59 AM - coil supression (bob noffs)
5. 10:49 AM - Re: Re: Coil Suppression Techniques (With Corrected Link) (John Cleary)
6. 11:14 AM - Re: Coil Suppression Techniques (Eric M. Jones)
7. 12:06 PM - Re: Re: Coil Suppression Techniques (Bob White)
8. 12:42 PM - Re: Coil Suppression Techniques ()
9. 12:54 PM - Re: Coil Suppression Techniques (Eric M. Jones)
10. 01:32 PM - Re: Re: Coil Suppression Techniques (Bob White)
11. 01:40 PM - Previous Master solonoid clicking (Bill Bradburry)
12. 03:08 PM - Re: Coil Suppression Techniques (John Cleary)
13. 04:22 PM - Coil Suppression Techniques. (Tony Gibson)
14. 07:24 PM - Re: Fuse and Breaker - one bus (Chris)
15. 07:29 PM - Re: Fuse and Breaker - one bus (Chris)
16. 08:36 PM - Re: Coil Suppression Techniques (Robert L. Nuckolls, III)
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Subject: | Coil Suppression Techniques |
Eric
This seems to be a well studied subject and after studying your results
the method of parallelling a relay or contactor with an opposite
direction diode seems to be the quick and dirty but still quite adequate
method for the homebuilder.
Now a very practical question:
Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle
the collapsing energy of any relay or contactor used in a homebuilt ?
best regards
Max
(just now wiring my 701 starter circuit)
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Subject: | Re: Coil Suppression Techniques |
Max,
1N5404 thru -8 series should do well with much more margin. I fitted one to the
master solenoid on a Cessna150 once because the A&P in their collective wisdom
neglected that small part as depicted it the Cessna parts book when replacing
the old solenoid and damaged my master switch.
My CH701 has a diode installed as required by the ACS ignition/start switch instructions
and I think this one may have come with the switch.
Ralph
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184325#184325
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Subject: | Re: Coil Suppression Techniques |
At 11:27 AM 5/22/2008 +0300, you wrote:
>Eric
>
>This seems to be a well studied subject and after studying your results
>the method of parallelling a relay or contactor with an opposite direction
>diode seems to be the quick and dirty but still quite adequate method for
>the homebuilder.
>
>Now a very practical question:
>
>Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle the
>collapsing energy of any relay or contactor used in a homebuilt
Yes. Electrically the 1A diode is fine for about everything
on the airplane. Recall that in the realm of reactive devices
that store energy, the discharge begins at the same magnitude
as the charging source. If you charge a capacitor to 100 volts, you
get a reaction that starts at 100v and goes down from there
when you discharge it.
If you charge and inductor up to 1A, then when you release
it from the charging source, the delivered reaction starts
a 1A and goes down from there. Diodes have a steady state
capability which is exemplified in their ratings . . . I.e,
the 1N4001 is a 1A device. However, they also have transient
ratings at much higher currents. For example, consulting the
1N400x data sheet at:
http://aeroelectric.com/Mfgr_Data/Semiconductors/1N4001.pdf
we read about an 8.3 mS non repetitive peak forward surge
current rating of 30A. By "non-repeating", they don't
mean "one time ever" but "just don't do this often." So as
a transient current clamp on a manually operated contactor
found in our airplanes the 1N400x series devices are
electrically fine.
However, I have often suggested that the larger siblings
to the 1N400x (1N540x) devices have some mechanical
advantages. They're still small but MUCH more robust
than the little fellers. I selected these parts as
power steering and coil suppressors of choice for the
line of contactors I used to sell (which B&C still
does). See:
http://www.aeroelectric.com/Pictures/Contactors/s701-1l.jpg
http://www.aeroelectric.com/Pictures/Contactors/s701-2.jpg
The red PIDG terminal gets a good connection on
the larger wires for these devices and the wires
are robust enough to support the diode body under
vibration levels typical of installations for
these contactors.
Radio Shack offers both sizes of diode:
http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg
Since a prohibition against Radio Shack parts has
been suggested, I'll share an observation that there
were times in the history of many suppliers of consumer/
experimenter parts where their offerings included
industrial surplus parts of unknown but not necessarily
evil pedigree. This includes a now premier supplier
of goods (Digikey) who started out as a mail
order supplier of industrial surplus that advertised
in ham radio and experimenter electronics magazines.
RS still handles experimenter's assortments of components
that are reminiscent of "grab bags" offered in years
gone by . . .
http://tinyurl.com/5jhbu6
http://tinyurl.com/42jn9v
. . . but these days, when you are responsible for
managing inventory in thousands of stores, millions
of catalogs, and a really big website, you don't
spend time scrounging the back alleys of industrial
trash cans looking for "floor sweepings".
These components are so cheap that it simply doesn't
pay to spend the time to salvage and then inventory
less than factory-fresh components.
The times they are a changing.
As a final note, this thread is not intended to
discourage anyone from using more sophisticated
transient control techniques if that process rings
their chimes. Information provided here is offered
as a prophylactic against decision making based
on poorly interpreted data, marketing hype, or sage
advice from those who would disseminate but will not
or cannot also teach.
Bob . . .
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i believe b and c supplies a diode when you order a solenoid.
bob noffs
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Subject: | Re: Coil Suppression Techniques (With Corrected |
Link)
Great data Bob.
Thanks,
John
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III
Sent: Thursday, 22 May 2008 9:50 AM
Subject: AeroElectric-List: Re: Coil Suppression Techniques (With Corrected Link)
At 05:47 PM 5/21/2008 -0500, you wrote:
<nuckolls.bob@cox.net>
At 07:42 AM 5/21/2008 -0700, you wrote:
I have this weird Deja Vu feeling that we have covered this subject before.
And I will save you the trouble Bob....I know you'll never agree, and
you'll retort with a long quasi-techno piece and then stumble TO EXACTLY
THE WRONG CONCLUSION.
Coil suppression and relay contact arcing have been well studied: See:
http://relays.tycoelectronics.com/appnotes/
Basically (ESPECIALLY with contactors) Do not use diodes for coil
suppression unless you're hoping for greatly reduced relay/contactor life,
so you can get stuck in a remote area and have an adventure. I know people
like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit!
You've cited that document before. And I've
read it several times both before you cited it
and after you cited it.
Kindly point out to me where the authors offer DATA
supporting an assertion that the plain vanilla
diode coil suppression has a profound effect on relay life.
They correctly asserted and I confirmed that
diodes do indeed extend the time from switch
opening until energized contacts begin to move.
This is opening delay. They went on to extrapolate
that opening delay translates directly into slower
contact spreading velocity and extrapolated further
that this translated to increased contact wear.
I did the experiments and published the results
that argue against their extrapolations. If you
have some data to the contrary, please share it
with us.
Just because you've read some words under the
letter head and over the signatures of persons
in high places does not make their words golden
unless they're supported by data from and
understanding of repeatable experiments.
Here's what sane people have figured out:
. . . are you suggesting I am less than sane??
Mechanical relays and contactors depend upon magnetism generated by an
electric current running through a wire coil. When the current stops, the
magnetic field collapses. But the relay does not know the difference
between a wire coil moving in a magnetic field (as in a generator) or a
magnetic field moving in a wire coil (as in a collapsing magnetic field).
Thus a large voltage1000V to 1500V typicallyis induced in the coil.
This current goes the same direction the original current didso it slows
the contact openingallowing arcing, chatter, bouncing, contact welding
and even re-closure! Yikes!
Go to your workbench, measure it, document
it and share it with us. Show me where my
data and interpretation of my data is wrong.
The important feature of relay and contactor
operation that you're overlooking is the extreme
relationship between magnetic force and air-gap.
Air is an exceedingly poor conductor of magnetic
lines of force. So while a diode does indeed slow
the rate of drop in coil current (hence increased
delay) once the armature comes unstuck from its
seated condition, the effect of increasing
air-gap is many times more influential than rate
of decay in coil current.
Went back to the workbench to look at the S704-1 in
more detail. Here's the test setup:
http://aeroelectric.com/Pictures/Schematics/Relay_Test_Setup.pdf
Relay response with no coil suppression looks
like this:
http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_without_Diode.jpg
where we see the high voltage spike on the coil
trace and a 2.5 mS dropout delay.
WITH a coil suppression diode, we get
relay response like this:
http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_with_Diode.jpg
Dropout Delay is increased to 12.5 mS or about 5x
longer than with the diode. This was the feature
pointed out in the article you cited . . . where
the authors extrapolated this into a commensurate
slowing in contact spreading velocity (longer fires).
However, when we take the diode off and look at
transition time . . .
http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_NoSuppression.jpg
From the time the contacts FIRST open until they
first contact the opposite side is 0.6 mS. Let's
put the diode back on and we get . . .
http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_Diode_Suppression.jpg
Hmmm . . . transition increases to 0.75 mS, about
a 25% increase NOT A 500% INCREASE.
Let's go back an look at the traces I took where
we were observing the arc in a spreading set of
contacts with no diode . . .
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif
Here I could see about 0.21 mS of "fire" as compared
with . . .
(Here's the right trace)
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif
about 0.23 mS arcing when the diode was in place. Hmmm,
there was an increase but not a very big one. In both
cases, observed arcing times were about 1/3 the total
transition time.
Now let us consider another feature of relays and contactors
that REALLY drives service life issues. Take a look at:
http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_with_Diode.jpg
Where we see that after the first time the contacts
touch, really get with the high-tempo hat-dance
for perhaps several dozen closure and re-opening
events. This means that for every operation of the
switch on the panel, the contacts are getting
5-25 times more activity than the single switching
event might suggest. Now look at:
http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg
Well fooey . . . even with the diode off the contacts
do the cat-on-a-hot-tin-roof routine.
Let us further consider that when folks like those Tyco
engineers evaluate service life, they're working in
the laboratory test environment and evaluating products
where service life is measured in the tens of thousands
of operations . . . 50,000 typical. 250,000 is not
unusual. Let us suppose that their paper was based on
real statistical studies of dozens of relays with
various coil suppression techniques and yes, there
was an observable increase in mean operations between
failures from 45,744 to 49,666 by "optimizing" the
coil suppression. Hmmm . . . 10% . . . that IS significant
to Tyco and probabably most of their customers.
They didn't speak to this kind of study in the paper
you cited and I'd like to believe they've done their
homework.
Let us assume their undocumented assertions
WERE correct on the scale I suggested. How does this
affect the OBAM aircraft builder who's switches,
relays and contactors probably won't see 5,000
operations over the lifetime of the airplane?
Further, environmental stresses will be root cause
for most replacements of such devices in personally owned,
non-revenue generating light aircraft, not electrical
stresses. In any case, the 5x increase in drop-out delay
DOES NOT extrapolate into a proportionate drop in contact
life.
The common palliative is a diode AND zener in series, or better yet, a
bidirectional zener across the coil. They call these Transils,
Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the
list is endless. (Over-paid executives dream up these names.) They are
generic P6KE18CA bidirectional zeners.
Jeeeeeze........
Eric,
Of all the contributors to this list I expect
more of you. We had some substantive discussions
on the inner technical workings of various products
and ideas in Plymouth a couple of years ago. You
struck me as one who appreciates understanding
and having a handle on the simple-ideas that go
into your recipes for success.
Please don't wave anyone's documents in the air as
justification for an extrapolation of my infirmities.
Let's not make this about you or me. May I suggest
we explore, understand and then explain the
physics. Make my day. Show me were I'm wrong.
Bob . . .
--
incoming mail is certified Virus Free.
Checked by AVG.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Checked by AVG.
Checked by AVG.
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Subject: | Re: Coil Suppression Techniques |
> Eric
> This seems to be a well studied subject and after studying your results the method
of parallelling a relay or contactor with an opposite direction diode seems
to be the quick and dirty but still quite adequate method for the homebuilder.
Now a very practical question: Is a 0.1 dollar 1N4001...4004 or similar diode
strong enough to handle the collapsing energy of any relay or contactor used
in a homebuilt ?
> best regards
> Max
The coil's collapsing magnetic field when the contactor is de-energized induces
a high current that travels in the same direction as the original holding current,
but is of much greater magnitude. This is why the relay contacts chatter
and arc on opening, can re-close (and even weld closed). This is bad for everything
electrical, especially contacts.
The bidirectional zeners are very cheap, and well worth it. The kit I sell will
do your whole airplane, or go to Digikey if you want to save a few bucks and
buy a dozen P6KE18CA.
The question you imply, "Would it do for the homebuilder?"....My answer is NO,
Bob's is YES. Take your pick.
But Tyco, Potter and Brumfield, Kilovac, Gigavac, Zettler,
Here's what Gigavac says: COIL SUPRESSION
"....coil suppression techniques such as single diode, resistor capacitor combination,
resistor, or varistor noticeably slow down the release time of the relay
and can effect the life of the relay or the use of the relay in the application.
In carry-only applications, the release time may not be important so these
less expensive coil suppression techniques can be used. However, if the release/reset
time is important, or if the contacts are to interrupt a load, do not
use these techniques and use the recommended zener-zener or diode-zener combination."
(underlining mine) Gigavac makes the GX-11 which is a great battery
and starter contactor for your airplane, they also make really big high-current,
high-voltage stuff.
Diodes were 1960's technology. There's a better way now.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184398#184398
Message 7
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Subject: | Re: Coil Suppression Techniques |
On Thu, 22 May 2008 11:11:37 -0700
"Eric M. Jones" <emjones@charter.net> wrote:
>
> The coil's collapsing magnetic field when the contactor is de-energized induces
a high current that travels in the same direction as the original holding current,
but is of much greater magnitude. This is why the relay contacts chatter
and arc on opening, can re-close (and even weld closed). This is bad for everything
electrical, especially contacts.
>
> The bidirectional zeners are very cheap, and well worth it. The kit I sell will
do your whole airplane, or go to Digikey if you want to save a few bucks and
buy a dozen P6KE18CA.
>
> The question you imply, "Would it do for the homebuilder?"....My answer is NO,
Bob's is YES. Take your pick.
>
> But Tyco, Potter and Brumfield, Kilovac, Gigavac, Zettler,
>
> Here's what Gigavac says: COIL SUPRESSION
>
> "....coil suppression techniques such as single diode, resistor capacitor combination,
resistor, or varistor noticeably slow down the release time of the relay
and can effect the life of the relay or the use of the relay in the application.
In carry-only applications, the release time may not be important so these
less expensive coil suppression techniques can be used. However, if the release/reset
time is important, or if the contacts are to interrupt a load, do
not use these techniques and use the recommended zener-zener or diode-zener combination."
(underlining mine) Gigavac makes the GX-11 which is a great battery
and starter contactor for your airplane, they also make really big high-current,
high-voltage stuff.
>
> Diodes were 1960's technology. There's a better way now.
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones@charter.net
>
>
I think we need to revisit the physics here. The collapsing field
induces a high VOLTAGE which is the opposite polarity of the applied
voltage. The faster the current decreases, the higher the voltage
spike. The suppression diode gives the current a place to go allowing
it to decay more slowly, producing a lower voltage, reducing the
arcing on the switch controlling the relay. The current will never
exceed the original current flowing in the coil.
Use of the suppression diode delays opening the relay because the
current continues to flow for a longer time. The important point is
that the suppression diode protects the switch controlling the relay.
The effects on the relay contact arcing are secondary.
Bob W.
--
N93BD - Rotary Powered BD-4 - http://www.bob-white.com
3.8 Hours Total Time and holding
Cables for your rotary installation - http://roblinstores.com/cables/
Message 8
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Subject: | Coil Suppression Techniques |
Thanks Bob et al,
This is all very academic and provides excellent reading. Unfortunately
I won't soon be a fellow in the IEEE and I have an airplane to build.
Given the list of manufacturer's provided is there one who makes a
quality relay with built in zener or combo protection for which I won't
need to break out the heath kit?
I want to use the relay to load my essential bus (alternate feed) as in
Z-19. My expect load will be 25 amps. This is in keeping with the max
load for the heat sink'd diode coming from the main bus.
Glenn
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L. Nuckolls, III
Sent: Thursday, May 22, 2008 9:13 AM
Subject: Re: AeroElectric-List: Coil Suppression Techniques
--> <nuckolls.bob@cox.net>
At 11:27 AM 5/22/2008 +0300, you wrote:
>Eric
>
>This seems to be a well studied subject and after studying your results
>the method of parallelling a relay or contactor with an opposite
>direction diode seems to be the quick and dirty but still quite
>adequate method for the homebuilder.
>
>Now a very practical question:
>
>Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle
>the
>collapsing energy of any relay or contactor used in a homebuilt
Yes. Electrically the 1A diode is fine for about everything
on the airplane. Recall that in the realm of reactive devices
that store energy, the discharge begins at the same magnitude
as the charging source. If you charge a capacitor to 100 volts, you
get a reaction that starts at 100v and goes down from there
when you discharge it.
If you charge and inductor up to 1A, then when you release
it from the charging source, the delivered reaction starts
a 1A and goes down from there. Diodes have a steady state
capability which is exemplified in their ratings . . . I.e,
the 1N4001 is a 1A device. However, they also have transient
ratings at much higher currents. For example, consulting the
1N400x data sheet at:
http://aeroelectric.com/Mfgr_Data/Semiconductors/1N4001.pdf
we read about an 8.3 mS non repetitive peak forward surge
current rating of 30A. By "non-repeating", they don't
mean "one time ever" but "just don't do this often." So as
a transient current clamp on a manually operated contactor
found in our airplanes the 1N400x series devices are
electrically fine.
However, I have often suggested that the larger siblings
to the 1N400x (1N540x) devices have some mechanical
advantages. They're still small but MUCH more robust
than the little fellers. I selected these parts as
power steering and coil suppressors of choice for the
line of contactors I used to sell (which B&C still
does). See:
http://www.aeroelectric.com/Pictures/Contactors/s701-1l.jpg
http://www.aeroelectric.com/Pictures/Contactors/s701-2.jpg
The red PIDG terminal gets a good connection on
the larger wires for these devices and the wires
are robust enough to support the diode body under
vibration levels typical of installations for
these contactors.
Radio Shack offers both sizes of diode:
http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg
Since a prohibition against Radio Shack parts has
been suggested, I'll share an observation that there
were times in the history of many suppliers of consumer/
experimenter parts where their offerings included
industrial surplus parts of unknown but not necessarily
evil pedigree. This includes a now premier supplier
of goods (Digikey) who started out as a mail
order supplier of industrial surplus that advertised
in ham radio and experimenter electronics magazines.
RS still handles experimenter's assortments of components
that are reminiscent of "grab bags" offered in years
gone by . . .
http://tinyurl.com/5jhbu6
http://tinyurl.com/42jn9v
. . . but these days, when you are responsible for
managing inventory in thousands of stores, millions
of catalogs, and a really big website, you don't
spend time scrounging the back alleys of industrial
trash cans looking for "floor sweepings".
These components are so cheap that it simply doesn't
pay to spend the time to salvage and then inventory
less than factory-fresh components.
The times they are a changing.
As a final note, this thread is not intended to
discourage anyone from using more sophisticated
transient control techniques if that process rings
their chimes. Information provided here is offered
as a prophylactic against decision making based
on poorly interpreted data, marketing hype, or sage
advice from those who would disseminate but will not
or cannot also teach.
Bob . . .
Message 9
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Subject: | Re: Coil Suppression Techniques |
> induces a high VOLTAGE which is the opposite polarity of the applied voltage.
The faster the current decreases, the higher the voltage
> spike. The suppression diode gives the current a place to go allowing
> it to decay more slowly, producing a lower voltage, reducing the
> arcing on the switch controlling the relay. The current will never
> exceed the original current flowing in the coil.
>
> Use of the suppression diode delays opening the relay because the
> current continues to flow for a longer time. The important point is
> that the suppression diode protects the switch controlling the relay.
> The effects on the relay contact arcing are secondary. Bob W.
> --
> N93BD - Rotary Powered BD-4 - http://www.bob-white.com
> 3.8 Hours Total Time and holding
> Cables for your rotary installation - http://roblinstores.com/cables/
>
If it were only so, what a nice world it would be! Please read:
http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3311.pdf
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184415#184415
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Subject: | Re: Coil Suppression Techniques |
On Thu, 22 May 2008 12:51:56 -0700
"Eric M. Jones" <emjones@charter.net> wrote:
>
>
> > induces a high VOLTAGE which is the opposite polarity of the applied voltage.
The faster the current decreases, the higher the voltage
> > spike. The suppression diode gives the current a place to go allowing
> > it to decay more slowly, producing a lower voltage, reducing the
> > arcing on the switch controlling the relay. The current will never
> > exceed the original current flowing in the coil.
> >
> > Use of the suppression diode delays opening the relay because the
> > current continues to flow for a longer time. The important point is
> > that the suppression diode protects the switch controlling the relay.
> > The effects on the relay contact arcing are secondary. Bob W.
> > --
> > N93BD - Rotary Powered BD-4 - http://www.bob-white.com
> > 3.8 Hours Total Time and holding
> > Cables for your rotary installation - http://roblinstores.com/cables/
> >
>
>
> If it were only so, what a nice world it would be! Please read:
>
> http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3311.pdf
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones@charter.net
>
OK, I've read it. What's your point?
Quote:
"When an electromechanical relay is de-energized rapidly by a mechanical
switch or semiconductor, the collapsing magnetic field produces a
substantial voltage transient in its effort to disperse the stored
energy and oppose the sudden change of current flow."
Note that this high voltage is not connected to the relay contacts and
there is no mention of high currents being generated. It just doesn't
happen. The high voltage is impressed across the switch controlling
the relay. As Ralph (jetboy) recently posted, the A&P left off the
diode resulting in the master switch being destroyed in his C150.
All the problems with relay contact opening are associated with the
slower opening time.
Another quote:
"The optimum switching life (for normally-open contacts) is therefore
obtainew with a totally unsuppressed relay and statements of rated
electrical life are usually based on this premise."
In other words, for best contact life, don't use suppression. So why
do we use it? To protect the controlling switch!
Bob W.
--
N93BD - Rotary Powered BD-4 - http://www.bob-white.com
3.8 Hours Total Time and holding
Cables for your rotary installation - http://roblinstores.com/cables/
Message 11
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Subject: | Previous Master solonoid clicking |
A while back, I discussed a clicking sound that I heard after I turned the
alternator on when the engine was running.
Today I discovered that my low voltage module was not working and when I
removed it, the clicking went away.
I tested the module by putting +9V on pin 4, grounded pin 5, and looked for
the LED to come on and also for a ground to show up on pin 1. No light, no
ground. Must have crapped out??!!
I also noticed that when the module was disconnected, If I had the main
battery set to "Alternator", and the engine battery set to "ON", I got about
13.4V. If I flipped the engine battery switch to "Auto", the voltage went
up to about 14.6V.
I was at a loss as to why this would be. I didn't try it with the engine
battery set to "OFF", so I don't know what would have happened if I did.
Does anyone have any ideas as to what was happening to cause the clicking if
the module caused it, and why the voltage increase? I at first thought..I
am turning one of the batteries off, so the voltage went up, but then I
thought...why wouldn't the voltage regulator bring it back down in that
case.
Thanks for the help!
Bill B
Message 12
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Subject: | Coil Suppression Techniques |
Bob,
Reading all these comments, two questions come to mind.
1. Have you done the tests below with a zener-zener or a diode-zener
combination to see how they compare with their IN 540x cousins?
2. Have you collected data on the effect on the switch controlling the relay
to compare the four conditions:-
No protection
IN540x protection
Zener-zerner protection
Diode-zener protection?
The data from question 1 will show us the effects on the relay under the
various conditions being discussed. The data from Q2 will show us the
effects on the switch controlling the relay under those same conditions. It
seems both lots of data are required to determine the best way to protect
the switch and at the same time protect the relay? - or am I missing
something in this debate?
Thanks once again,
John
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, 22 May 2008 11:13 PM
Subject: Re: AeroElectric-List: Coil Suppression Techniques
<nuckolls.bob@cox.net>
At 11:27 AM 5/22/2008 +0300, you wrote:
>Eric
>
>This seems to be a well studied subject and after studying your results
>the method of parallelling a relay or contactor with an opposite direction
>diode seems to be the quick and dirty but still quite adequate method for
>the homebuilder.
>
>Now a very practical question:
>
>Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle the
>collapsing energy of any relay or contactor used in a homebuilt
Yes. Electrically the 1A diode is fine for about everything
on the airplane. Recall that in the realm of reactive devices
that store energy, the discharge begins at the same magnitude
as the charging source. If you charge a capacitor to 100 volts, you
get a reaction that starts at 100v and goes down from there
when you discharge it.
If you charge and inductor up to 1A, then when you release
it from the charging source, the delivered reaction starts
a 1A and goes down from there. Diodes have a steady state
capability which is exemplified in their ratings . . . I.e,
the 1N4001 is a 1A device. However, they also have transient
ratings at much higher currents. For example, consulting the
1N400x data sheet at:
http://aeroelectric.com/Mfgr_Data/Semiconductors/1N4001.pdf
we read about an 8.3 mS non repetitive peak forward surge
current rating of 30A. By "non-repeating", they don't
mean "one time ever" but "just don't do this often." So as
a transient current clamp on a manually operated contactor
found in our airplanes the 1N400x series devices are
electrically fine.
However, I have often suggested that the larger siblings
to the 1N400x (1N540x) devices have some mechanical
advantages. They're still small but MUCH more robust
than the little fellers. I selected these parts as
power steering and coil suppressors of choice for the
line of contactors I used to sell (which B&C still
does). See:
http://www.aeroelectric.com/Pictures/Contactors/s701-1l.jpg
http://www.aeroelectric.com/Pictures/Contactors/s701-2.jpg
The red PIDG terminal gets a good connection on
the larger wires for these devices and the wires
are robust enough to support the diode body under
vibration levels typical of installations for
these contactors.
Radio Shack offers both sizes of diode:
http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg
Since a prohibition against Radio Shack parts has
been suggested, I'll share an observation that there
were times in the history of many suppliers of consumer/
experimenter parts where their offerings included
industrial surplus parts of unknown but not necessarily
evil pedigree. This includes a now premier supplier
of goods (Digikey) who started out as a mail
order supplier of industrial surplus that advertised
in ham radio and experimenter electronics magazines.
RS still handles experimenter's assortments of components
that are reminiscent of "grab bags" offered in years
gone by . . .
http://tinyurl.com/5jhbu6
http://tinyurl.com/42jn9v
. . . but these days, when you are responsible for
managing inventory in thousands of stores, millions
of catalogs, and a really big website, you don't
spend time scrounging the back alleys of industrial
trash cans looking for "floor sweepings".
These components are so cheap that it simply doesn't
pay to spend the time to salvage and then inventory
less than factory-fresh components.
The times they are a changing.
As a final note, this thread is not intended to
discourage anyone from using more sophisticated
transient control techniques if that process rings
their chimes. Information provided here is offered
as a prophylactic against decision making based
on poorly interpreted data, marketing hype, or sage
advice from those who would disseminate but will not
or cannot also teach.
Bob . . .
Checked by AVG.
7:21 AM
Checked by AVG.
7:06 AM
Message 13
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Subject: | Coil Suppression Techniques. |
Hi Bob, on-behalf of myself and many others I'm sure I'd like to thank yo
u for - first of all, your restraint, and of course-your informative post
s that make it so easy for the rest of us to click-on the links of your
-experiments.=0AI joined this list probably two years ago and a great dea
l of what was discussed was over my head (and still is!) ... I received the
daily emails and for the longest time would-check out the subject titles
and more often than not delete the email.- Over time I've 'gotten up to
speed', read your book, and spent the time to-learn-(whether the partic
ular subject concerned my airplane or not).-=0AIt's all too easy to "gold
plate the spec" to cover ALL conceivable conditions that a particular comp
onent may see whether applicable or not.- It is of GREAT value to me that
you repeatedly base your responses on OBAM-aircraft.- Meaning... if ag
e/environmental factors, etc is going to kill my component before I or my d
esigned system does then thats exactly what I need to know.--I have alw
ays found your posts and advice to be practical in the real world (where mo
st of us live with our little homebuilt airplanes)-and considerate of my
time & money.=0AI continue to learn from all the contributors and contribut
ions to the site.- Best Regards to all and my apologies for feeling the n
eed to 'waste' bandwidth!- ;)=0ATony Gibson=0AWinnipeg, Manitoba-=0A=0A
Time: 03:51:31 PM PST US=0AFrom: "Robert L. Nuckolls, III" <nuckolls.bob@co
x.net>=0ASubject: Re: AeroElectric-List: Coil Suppression Techniques.=0A=0A
=0AAt 07:42 AM 5/21/2008 -0700, you wrote:=0A=0A>=0A>I have this weird Deja
Vu feeling that we have covered this subject =0A>before. And I will save y
ou the trouble Bob....I know you'll never agree, =0A>and you'll retort with
a long quasi-techno piece and then stumble TO =0A>EXACTLY THE WRONG CONCLU
SION.=0A>=0A>Coil suppression- and relay contact arcing have been well st
udied: See:=0A=0A>http://relays.tycoelectronics.com/appnotes/=0A>=0A>Basica
lly (ESPECIALLY with contactors) Do not use diodes for coil =0A>suppression
unless you're hoping for greatly reduced relay/contactor life, =0A>so you
can get stuck in a remote area and have an adventure. I know people =0A>lik
e this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit!=0A
=0A- You've cited that document before. And I've=0A- read it several ti
mes both before you cited it=0A- and after you cited it.=0A=0A- Kindly
point out to me where the authors offer DATA=0A- supporting an assertion
that the plain vanilla=0A- diode coil suppression has a profound effect o
n relay life.=0A=0A- They correctly asserted and I confirmed that=0A- d
iodes do indeed extend the time from switch=0A- opening until energized c
ontacts begin to move.=0A- This is opening delay. They went on to extrapo
late=0A- that opening delay translates directly into slower=0A- contact
spreading velocity and extrapolated further=0A- that this translated to
increased contact wear.=0A=0A- I did the experiments and published the re
sults=0A- that argue against their extrapolations. If you=0A- have some
data to the contrary, please share it=0A- with us.=0A=0A- Just because
you've read some words under the=0A- letter head and over the signatures
of persons=0A- in high places does not make their words golden=0A- unl
ess they're supported by data from and=0A- understanding of repeatable ex
periments.=0A=0A>Here's what sane people have figured out:=0A=0A- . . .
- are you suggesting I am less than sane??=0A=0A>Mechanical relays and co
ntactors depend upon magnetism generated by an =0A>electric current running
through a wire coil. When the current stops, the =0A>magnetic field collap
ses. But the relay does not know the difference =0A>between a wire coil mov
ing in a magnetic field (as in a generator) or a =0A>magnetic field moving
in a wire coil (as in a collapsing magnetic field). =0A>Thus a large voltag
e1000V to 1500V typicallyis induced in the coil. =0A>This current goes the
same direction the original current didso it =0A>slows the contact openinga
llowing arcing, chatter, bouncing, contact =0A>welding and even re-closure!
Yikes!=0A=0A- Go to your workbench, measure it, document=0A- it and sh
are it with us. Show me where my=0A- data and interpretation of my data i
s wrong.=0A=0A- The important feature of relay and contactor=0A- operat
ion that you're overlooking is the extreme=0A- relationship between magne
tic force and air-gap.=0A- Air is an exceedingly poor conductor of magnet
ic=0A- lines of force. So while a diode does indeed slow=0A- the rate o
f drop in coil current (hence increased=0A- delay) once the armature come
s unstuck from its=0A- seated condition, the effect of increasing=0A- a
ir-gap is many times more influential than rate=0A- of decay in coil curr
ent.=0A=0A- Went back to the workbench to look at the S704-1 in=0A- mor
e detail. Here's the test setup:=0A=0A=0Ahttp://aeroelectric.com/Pictures/S
chematics/Relay_Test_Setup.pdf=0A=0A- Relay response with no coil suppres
sion looks=0A- like this:=0A=0Ahttp://www.aeroelectric.com/Pictures/Curve
s/S704-1_Drop-Out_Delay_without_Diode.jpg=0A=0A- where we see the high vo
ltage spike on the coil=0A- trace and a 2.5 mS dropout delay.=0A=0A- WI
TH a coil suppression diode, we get=0A- relay response like this:=0A=0Aht
tp://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_with_Diode.
jpg=0A=0A- Dropout Delay is increased to 12.5 mS or about 5x=0A- longer
than with the diode. This was the feature=0A- pointed out in the article
you cited . . . where=0A- the authors extrapolated this into a commensur
ate=0A- slowing in contact spreading velocity (longer fires).=0A=0A- Ho
wever, when we take the diode off and look at=0A- transition time . . .
=0A=0Ahttp://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_NoS
uppression.jpg=0A=0A- From the time the contacts FIRST open until they=0A
- first contact the opposite side is 0.6 mS. Let's=0A- put the diode ba
ck on and we get . . .=0A=0Ahttp://www.aeroelectric.com/Pictures/Curves/S70
4-1_D-E_Transition_Diode_Suppression.jpg=0A=0A- Hmmm . . . transition inc
reases to 0.75 mS, about=0A- a 25% increase NOT A 500% INCREASE.=0A=0A-
Let's go back an look at the traces I took where=0A- we were observing t
he arc in a spreading set of=0A- contacts with no diode . . .=0A=0Ahttp:/
/www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif=0A=0A-
Here I could see about 0.21 mS of "fire" as compared=0A- with . . .=0A=0A
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif=0A
=0A- about 0.23 mS arcing when the diode was in place. Hmmm,=0A- there
was an increase but not a very big one. In both=0A- cases, observed arcin
g times were about 1/3 the total=0A- transition time.=0A=0A- Now let us
consider another feature of relays and contactors=0A- that REALLY drives
service life issues. Take a look at:=0A=0Ahttp://www.aeroelectric.com/Pict
ures/Curves/S704-1_Contact_Bounce_with_Diode.jpg=0A=0A- Where we see that
after the first time the contacts=0A- touch, really get with the high-te
mpo hat-dance=0A- for perhaps several dozen closure and re-opening=0A-
events. This means that for every operation of the=0A- switch on the pane
l, the contacts are getting=0A- 5-25 times more activity than the single
switching=0A- event might suggest. Now look at:=0A=0Ahttp://www.aeroelect
ric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg=0A=0A- We
ll fooey . . . even with the diode off the contacts=0A- do the cat-on-a-h
ot-tin-roof routine.=0A=0A- Let us further consider that when folks like
those Tyco=0A- engineers evaluate service life, they're working in=0A-
the laboratory test environment and evaluating products=0A- where service
life is measured in the tens of thousands=0A- of operations . . . 50,000
typical. 250,000 is not=0A- unusual. Let us suppose that their paper was
based on=0A- real statistical studies of dozens of relays with=0A- var
ious coil suppression techniques and yes, there=0A- was an observable inc
rease in mean operations between=0A- failures from 45,744 to 49,666 by "o
ptimizing" the=0A- coil suppression. Hmmm . . . 10% . . . that IS signifi
cant=0A- to Tyco and probabably most of their customers.=0A- They didn'
t speak to this kind of study in the paper=0A- you cited and I'd like to
believe they've done their=0A- homework.=0A=0A- Let us assume their und
ocumented assertions=0A- WERE correct on the scale I suggested. How does
this=0A- affect the OBAM aircraft builder who's switches,=0A- relays an
d contactors probably won't see 5,000=0A- operations over the lifetime of
the airplane?=0A=0A- Further, environmental stresses will be root cause
=0A- for most replacements of such devices in personally owned,=0A- non
-revenue generating light aircraft, not electrical=0A- stresses. In any c
ase, the 5x increase in drop-out delay=0A- DOES NOT extrapolate into a pr
oportionate drop in contact=0A- life.=0A=0A=0A>The common palliative is a
diode AND zener in series, or better yet, a =0A>bidirectional zener across
the coil. They call these Transils, =0A>Surmetics, Transorbs, TranZorbs, T
ransGuards, Mosorbs; the =0A>list is endless. (Over-paid executives dream u
p these names.)- They are =0A>generic P6KE18CA bidirectional zeners.=0A>
=0A>Jeeeeeze........=0A=0A- Eric,=0A=0A- Of all the contributors to thi
s list I expect=0A- more of you. We had some substantive discussions=0A
- on the inner technical workings of various products=0A- and ideas in
Plymouth a couple of years ago. You=0A- struck me as one who appreciates
understanding=0A- and having a handle on the simple-ideas that go=0A- i
nto your recipes for success.=0A=0A- Please don't wave anyone's documents
in the air as=0A- justification for an extrapolation of my infirmities.
=0A- Let's not make this about you or me. May I suggest=0A- we explore,
understand and then explain the=0A- physics. Make my day. Show me were I
'm wrong.=0A=0A- Bob . . .=0A=0A=0A
Message 14
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Subject: | Re: Fuse and Breaker - one bus |
Thanks Bob. I see your point and will continue along those lines you
describe. I have been thinking I may want to see an indication of a failure
on certain items by seeing that breaker button pop out. Is that really
something I need to see or know or do I use another indicator like a light?
-Chris
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@cox.net>
Sent: Tuesday, May 20, 2008 11:33 PM
Subject: Re: AeroElectric-List: Fuse and Breaker - one bus
> <nuckolls.bob@cox.net>
>
> At 09:16 AM 5/20/2008 -0400, you wrote:
>
>><toaster73@embarqmail.com>
>>
>>I have been lurking here for a few years trying to absorb the power of
>>aeroelectric but I am having trouble jumping from the schematics to the
>>physical configuration.
>>I am having trouble with the physical configuration of my RV-10 electrical
>>system design. I am trying to draw up a Z-13 style system but I think I
>>want my E-Bus to have a breaker for trim, flaps etc but the rest I want to
>>use a fuse block. What would be a good way to combine the fuse and
>>breaker block into one bus? Just run same gage wire to the e-bus primary
>>and alternate feed to the fuse block and split off from block with same
>>gage wire to the bar for the breakers?
>>thanks in advance
>
> The e-bus is for things that you need during the en-route
> mode of flight to maximize utilization of a limited resource.
> If you're planning Z-13/8, then the e-bus can be easily
> configured to handle an endurance load of 8 amps.
>
> The idea is that when the airport is in sight that you
> can bring the main bus back on for using the battery to
> run anything on the main bus using a battery that's held
> completely in reserve for approach to landing.
>
> What's your rationale for breakers on these two systems?
> Runaway disconnect? Breakers are exceedingly poor substitutes
> for master disconnect systems . . . if indeed runaway is
> a high order probability for creating a hazard. It's
> probably easier to design a system that can't run away.
> In other words, trim is an exceedingly low duty-cycle
> load that runs happily from the e-bus . . . Flaps too
> for that matter . . . but they aren't needed until approach
> to landing and could stay on the main bus. I guess we
> need to understand your concnerns.
>
> Bob . . .
>
>
>
Message 15
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Subject: | Re: Fuse and Breaker - one bus |
Vaughn,
I had an MGB and am familiar with the Prince of Darkness. Your right I
probably should not be doing wiring - to me this is the coolest part of the
project when its done, but the worst to figure out and build. I am a
mechanical guy through and through.
-Chris
----- Original Message -----
From: "Gaye and Vaughn" <vaughnray@bvunet.net>
Sent: Tuesday, May 20, 2008 10:48 PM
Subject: Re: AeroElectric-List: Fuse and Breaker - one bus
> <vaughnray@bvunet.net>
>
> The fuse block is your endurance bus. I would run a wire to the fuse block
> post that would handle the combined loads on the fuse block and the load
> on your breaker bar. I would then run a wire from the post on the fuse
> block to the breaker bar that was large enough to handle the combined
> loads of all the breakers.
>
> I once had an MGTF with Lucas electrics. Are you should be wiring? ;-)
>
> Vaughn Teegarden
> Trying to figure it out myself...Don't listen to me.
>
> ----- Original Message -----
> From: "Chris" <toaster73@embarqmail.com>
> To: <aeroelectric-list@matronics.com>
> Sent: Tuesday, May 20, 2008 9:16 AM
> Subject: AeroElectric-List: Fuse and Breaker - one bus
>
>
>> <toaster73@embarqmail.com>
>>
>> I have been lurking here for a few years trying to absorb the power of
>> aeroelectric but I am having trouble jumping from the schematics to the
>> physical configuration.
>> I am having trouble with the physical configuration of my RV-10
>> electrical system design. I am trying to draw up a Z-13 style system but
>> I think I want my E-Bus to have a breaker for trim, flaps etc but the
>> rest I want to use a fuse block. What would be a good way to combine the
>> fuse and breaker block into one bus? Just run same gage wire to the e-bus
>> primary and alternate feed to the fuse block and split off from block
>> with same gage wire to the bar for the breakers?
>> thanks in advance
>> Chris Lucas
>> RV-10 #40072
>>
>>
>>
>>
>
>
>
Message 16
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Subject: | Coil Suppression Techniques |
At 08:03 AM 5/23/2008 +1000, you wrote:
>
>Bob,
>
>Reading all these comments, two questions come to mind.
>
>1. Have you done the tests below with a zener-zener or a diode-zener
>combination to see how they compare with their IN 540x cousins?
Absolutely. The the worse case voltage spike occurs with zero
suppression (where all energies are dissipated in the arcing
across spreading switch contacts). The best scenario for arcing
control is the plain vanilla diode where arcing is minimal
because the negative going spike that would normally go -300 volts
plus is clamped off at ground thus limiting the voltage stress
across the switch contacts to 14 volts.
>2. Have you collected data on the effect on the switch controlling the relay
>to compare the four conditions:-
> No protection
> IN540x protection
> Zener-zerner protection
> Diode-zener protection?
Sure. They all work within the limits of their physics.
Even a plain resistor adds significant value for arc
reduction . . . even if the least efficient of the lot.
A capacitor/resistor combination works too. Recall the
"condenser" across the points on an Kettering ignition
system distributor? There's a LOT of ways each offering
trade offs. But to date, I've discovered no simpler, easier
to implement technique than use of the plain-vanilla
diode.
>The data from question 1 will show us the effects on the relay under the
>various conditions being discussed. The data from Q2 will show us the
>effects on the switch controlling the relay under those same conditions. It
>seems both lots of data are required to determine the best way to protect
>the switch and at the same time protect the relay? - or am I missing
>something in this debate?
I looked at all these variations and quite frankly they
performed well. I thought I had the traces on
my hard drive but I don't find them. If I get time tomorrow,
I'll go plot them again.
I've not included them in my offerings of data because
they are all middle-ground for performance between NO
suppression and the ULTIMATE suppression of a plain-vanilla
diode.
With one exception. At one time I personally embraced low
voltage MOV's as viable contact preservation devices
but discarded them after I went to the bench to check
performance when a reader told me of his own experiments
where visible arcing was not attenuated by any observable
amount with MOVs. I was properly embarrassed and dutiful
in correcting the gaff. It's one of those things that
happens when understanding based on data sheets does
not mesh with real world experiences.
The debate here is not whether the alternative systems
do their job. The debate is whether there is return
on investment for acquiring "specialized"
components sold not upon hard data and repeatable
experiment. The only support is a kind of "new and
improved" marketing hype based on poorly extrapolated
conclusions in a "celebrity" document. In this case,
engineers that published under the Tyco trade name.
It appears Eric is unwilling to be a teacher based on
his personal understanding of the physics supported
by a willingness to explain it. I am saddened by
this. I'll go get the data on the alternative techniques
tomorrow.
Bob . . .
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