Today's Message Index:
----------------------
1. 02:44 AM - Re: Re: Diodes across relay coils (KITFOXZ@aol.com)
2. 05:53 AM - Re: Re: Diodes across relay coils (Ken)
3. 07:57 AM - Re: Diodes across relay coils (Eric M. Jones)
4. 08:15 AM - Fw: Diodes for Master and Starter relays (Joe & Jan Connell)
5. 08:19 AM - Tyco/Raychem solder sleeves (Ken Simmons)
6. 08:38 AM - Re: Re: Diodes across relay coils (Paul Messinger)
7. 08:38 AM - Re: Re: Circuit breaker ratings for OVP (Paul Messinger)
8. 08:38 AM - Re: Diodes for Master and Strater relays (Robert L. Nuckolls, III)
9. 08:39 AM - Re: EGT interference (Robert L. Nuckolls, III)
10. 08:41 AM - Re: Diode question (Robert L. Nuckolls, III)
11. 08:48 AM - Re: Fw: Diodes for Master and Starter relays (Paul Messinger)
12. 08:49 AM - Re: Re: Circuit breaker ratings for OVP (Robert L. Nuckolls, III)
13. 08:56 AM - Re: Diodes for Master and Strater relays (Paul Messinger)
14. 09:16 AM - Re: Re: Circuit breaker ratings for OVP (Paul Messinger)
15. 10:23 AM - Re: Diode question (Bob C.)
16. 10:32 AM - All this overvoltage stuff.... (simon miles)
17. 01:36 PM - Re: All this overvoltage stuff.... (Eric M. Jones)
18. 01:53 PM - Re: Re: All this overvoltage stuff.... (Dj Merrill)
19. 05:34 PM - Re: Re: Circuit breaker ratings for OVP (Andrew Rowley)
20. 06:52 PM - Re: Re: Circuit breaker ratings for OVP (Paul Messinger)
21. 07:00 PM - Re: Re: All this overvoltage stuff.... (John Allen)
22. 08:48 PM - Re: Re: Diodes across relay coils (Ken)
23. 09:27 PM - Re: Diode question (Robert L. Nuckolls, III)
24. 11:32 PM - Re: Sigtronics intercom wiring and 12-channel annunciator (rv-9a-online)
Message 1
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: KITFOXZ@aol.com
In a message dated 3/25/2005 12:08:36 A.M. Eastern Standard Time,
retasker@optonline.net writes:
Actually Paul did say bidirectional transorb. He also mentioned if you
use a uni-directional transorb you must also use a series diode with it.
A bi-directional transorb must have a sufficiently high breakdown
voltage so it never turns on with normal battery/alternator voltage
present - i.e. use one with at least a 16V breakdown.
Before silicon diodes were common, a neon "grain of wheat" bulb (a
bi-directional device) was used to halt relay bounce and save contacts from abuse.
I
used to find comfort in watching the neons fire knowing that my device was
being saved from unnecessary destruction.
John P. Marzluf
Columbus, Ohio
Kitfox Outback (out back in the garage)
Message 2
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
Yup!
99.99% of the engineering world also protected their circuitry from 20
volt and highter negative spikes which may have been more imortant to
them. Sensationalist statements may catch attention but there is more to
this story and it seems to me that there are tradeoffs that should
accompany such a claim...
Ken
(in no hurry to remove my diodes)
Matt Prather wrote:
>--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
>
>Reading both of these messages, it might sound like using a flyback
>diode is worse than nothing. Is that the point? Or is it that flyback
>diodes
>only fix one kind of problem (arcing from the collapsing field caused by
>the high dI/dt), but might make a different one worse (somewhat increase
>contact bounce by slowing/reversing armature motion)?
>
>Does anyone have data to quantify how much longer the contacts will live
>with no protection, vs. diode protection, vs. transorbs? That would be
>useful.
>
>
>Regards,
>
>Matt-
>VE N34RD, C150 N714BK
>
>
>
>
>>--> AeroElectric-List message posted by: "Eric M. Jones"
>><emjones@charter.net>
>>
>>--> AeroElectric-List message posted by: "Paul Messinger"
>><paulm@olypen.com>
>>
>>
>>
>>>For decades 99.999% of the engineering world recommended and used the
>>>
>>>
>>common rectifier diode across inductors like relay coils to suppress the
>>inductive spike that happens hen the power to the inductor is
>>interrupted.
>>
>>Hey, my dad taught me this technique....And he claimed never to be
>>wrong. Usually.
>>
>>
>>
>>>snip
>>>
Message 3
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>Yup!
>99.99% of the engineering world also protected their circuitry from 20
>volt and highter negative spikes which may have been more imortant to
>them. Sensationalist statements may catch attention but there is more to
>this story and it seems to me that there are tradeoffs that should
>accompany such a claim...Ken
Ken,
Science on the march. Please read and comment on the Tyco and Kilovac
references. Potter and Brumfield is synonymous with "relays". They don't
kid around.
It is usually true that the best technology comes just when the technology
is on its way out. Those steam-turbine locomotives were fabulous. So here we
are in a solid state world and they finally figured out how to make relays
work better. Sensationalist? Not me. But I had a customer who had TWO
starter contactors weld closed in his Lancair. I'll bet he'll be changing
the diodes this weekend.
>(in no hurry to remove my diodes)
So don't.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
"A man's got to know his limitations."
(Clint Eastwood's Dirty Harry in Magnum Force, 1973)
Message 4
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| Subject: | Fw: Diodes for Master and Starter relays |
--> AeroElectric-List message posted by: "Joe & Jan Connell" <jconnell@rconnect.com>
Hi Guys,
Thanks for all your discussion on this topic. In review of
http://relays.tycoelectronics.com/kilovac/appnotes/transients.stm
it appears the zener-zener method is preferred. After searching
through the Digikey catalog it looks like I should get a pair of zener
diodes, solder the cathode ends together, and connect the anode
ends to relay terminals after covering them with heat-shrink tubing.
Am I in the ball park on this?
Are 5 watt, 16 volt zener diodes acceptible?
Looks like I can do this for a couple of bucks. All I really need are
part numbers, wattages, and voltages. I don't have the background
to process the technical nuances of the various solutions.
Thanks again...
Joe Connell
Stewartville, MN
RV-9A N95JJ wiring
Message 5
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| Subject: | Tyco/Raychem solder sleeves |
--> AeroElectric-List message posted by: "Ken Simmons" <ken@truckstop.com>
Bob,
Do you know of a good source for these that doesn't require a 100's quantity? I
found some from Mouser, but they are the CWT series not the SO96 that you used.
The SO96 seems to be a much better choice.
Thanks.
Ken
Message 6
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
The bidirectional transorbs clamp the negative spikes to less than 20 volts
and also have no side affects of merit like contact bounce which is hard on
contacts (not to mention making noise and other potentially nasty things).
Lets consider a worst case. Your alternator runs away and the OVP trips the
CB and the "B" lead contactor stays closed due to contact welding.. This
because you usde a simple diode.
I recommend you really read the referenced articles before deciding
anything.
There is no way to tell when of if a contact will weld. Could happen right
away or never. Sure it reduces lifecycle of the contact but there is no
assurance this reduction will still be above 1000 or what ever. Too many
variables including the power thru the contacts vs the contact rating.
Contacts can be damaged from too little power as well as the popular cases
of too much power. AC ratigs do not always convert to DC ratings. Only ONE
hi load current thru a contact typically damages the ability of the contacts
to properly switch low currents.
In aerospace industry way back when we used relays we has contact r/c
networks across every relay contact.
Personally the large contactors are the main concern as their mass is larger
and thus move slower to between with.
Just because most of the world is misusing the common silicon diode as a
coil spike controller does not mean its correct. There is lots of science to
support the references I have quoted as well as Major relay manufacturers,
world wide, that support the notion that a simple diode is not good.
We all know that something must be done about the inductive spike across the
relay coil. The referenced articles simply show that short of nothing the
worst thing you can use is the common diode. Replacing this one part with a
same sized but different type part does the dame job with out the negative
side affects.
The only reason not to use the better part is lack of willingness to redo it
if you have already installed the simple diodes.
New builders should use transorbs and forget considering silicon rectifier
diodes. The cost at mouser for small quantities is under $0.50 each
depending on the brand you pick.
Paul
PS its not me than cannot smell words korekly its my Komputor and mickety
soft smell ckre what cannot tell one word from another amd thus allows
incorrect words to be used out of kontext. :-)
----- Original Message -----
From: "Ken" <klehman@albedo.net>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
> Yup!
> 99.99% of the engineering world also protected their circuitry from 20
> volt and highter negative spikes which may have been more imortant to
> them. Sensationalist statements may catch attention but there is more to
> this story and it seems to me that there are tradeoffs that should
> accompany such a claim...
> Ken
> (in no hurry to remove my diodes)
>
Message 7
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| Subject: | Re: Circuit breaker ratings for OVP |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
You are correct IF 35 milliohms was the fixed value you and Bob have used in
calculations.
However 35 milliohms is only the max specified and in my case the measured
value was far less in some cases.
Thus the often asked for and so far never documented worst case analysis.
That is to take both the max and min possible values for every element in
the circuit and use the values minimizing current (for example) and then the
values maximizing current and getting the range of currents.
Bob has suggested that a couple hundred amps is the maximum and I have
demonstrated that over 400 is real. Neither of us has done a worst case
analysis so the real current range is above 400 amps and the minimum is very
likely to be above 100 amps using reasonable wiring etc.
Paul
----- Original Message -----
From: "Ken" <klehman@albedo.net>
Subject: Re: AeroElectric-List: Re: Circuit breaker ratings for OVP
> --> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
> But is it an arbitrarilly large current at the specified voltages and
> with wires that can reasonably be attached to the device? One of the
> examples mentioned about 35 miliohms resistance for the breaker. Well if
> a 12volt battery is pulled down to say 10 volts then you simply can't
> get more than 10 / 0.035 =286 amps even with a zero impedance (at 10
> volts) battery and zero resistance wires and connectors! But it would be
> less with real wires, real connectors, and a real battery. OK double
> that for a 24 volt system but it still isn't arbitrarilly large.
>
> N'other thing worth consideration might be reliability and the failure
> modes of OVP devices. A crowbar that does nothing in normal ops might
> have a higher probability of failing passively in normal operations
> compared to a device that must continuously conduct field curent to keep
> the alternator running??
>
> Ken
>
> Eric M. Jones wrote:
>
>>--> AeroElectric-List message posted by: "Eric M. Jones"
>><emjones@charter.net>
>>
>>Bob, et al.
>>
>>It would seem improbably at best that a circuit breaker could be built to
>>survive an arbitrarily large overcurrent. As Paul has pointed out, the
>>addition of a small resistor will put this crowbar back into the barn.
>>
>>
> >snip
>
>
>
Message 8
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| Subject: | Re: Diodes for Master and Strater relays |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 09:36 AM 3/24/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: "Joe & Jan Connell"
><jconnell@rconnect.com>
>
>Hi Guys,
>
>I've been searching the AeroElectric-List and the RV-list to
>get information on which diode to use across these relays.
>Can you provide me a diode part number and ratings? I'd
>rather not buy the prepackaged solution from Van's...
ANY diode will work. There's not a rectifier diode
made that doesn't have sufficient current and voltage
ratings to do the task. My persona favorites are the
1N5400 series devices. You can get them from Radio
Shack in packages of 2 for about $1.50
See:
http://www.aeroelectric.com/Pictures/RS_Diodes.jpg
These have some mechanical robustness that makes them
easier to work with and more resistant to mechanical
failure in service. See:
http://www.aeroelectric.com/Pictures/s701-1l.jpg
http://www.aeroelectric.com/Pictures/s701-2.jpg
You can find some starter contactors having built
in diodes. This was the variety we used to sell.
The contactors we sold said "diode protected"
right on the base. When in doubt, put an external
diode on . . . two diodes doesn't hurt but no
diode can be a problem See:
http://aeroelectric.com/articles/spikecatcher.pdf
Bob . . .
Message 9
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| Subject: | Re: EGT interference |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 08:36 AM 3/24/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: drshufly@aol.com
>
>My Glasair EGT/CHT readings (as read on my RMI Micromonitor) are steady
>until I energize the Whelan strobe system and then they jump around
>several hundred degrees. I'm wondering if a Radio Shack noise filter on
>the strobe power supply might correct this situation. Closest point of
>approach for any mutual wire is twelve inches; strobes are the instigator;
>EGT/CHT is the victim so I wonder if a filter would do any good. Could
>the problem be simply RFI coming from the strobes? Would appreciate comments.
>Bob Shumaker in Virginia
It's most likely a conducted noise as opposed to radiated
noise problem. Have you tried running the EGT from its
own battery to see if the effect goes away?
Bob . . .
Message 10
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| Subject: | Re: Diode question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
If you're needing to really LOAD up the e-bus normal feed
diode this hard, I'm wondering if you have too much 'stuff'
on the e-bus or perhaps the wrong z-figure selected for
your airplane.
Bob . . .
At 06:07 PM 3/23/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
>Yellow PIDG faston terminals are available from digi-key in
>(min.quantity 10) and work fine on 10 and 12 awg wire.
>Ken
>
>Travis Hamblen wrote:
>
> >--> AeroElectric-List message posted by: "Travis Hamblen"
> <TravisHamblen@cox.net>
> >
> >I am using Z-11 plan and have a couple questions that you guys will
> >definitely know about. First, I am using the suggested steering diode
> >between the main and essential bus (using the heat sink). The question is
> >that because of the amperage I am sending through this diode ( < 25a but
> >sometimes > 20a) I will be using 10awg wire which means I can't use a fast
> >on terminal because they don't make them for awg that large. SO would a
> >good alternative be to solder the wires to the fast on connectors on the
> >diode? If I did this would it be just as secure, I was concerned that with
> >all the vibration in an RV that the solder could break away after a while.
> >I would prefer to use a fast on, but haven't been able to find fast ons for
> >awg smaller than 14awg; if someone has a source for these please let me
> >know!
> >
> >The second question is about the fuse that the steering diode calls for.
> >The diode is only rated up to a max of 25a and this is a perfect match for
> >my system. However, it also calls for the use of a breaker or fuse on the
> >two wires going to the main bus. I was thinking of using an automotive
> >style inline fuse that would use a 30a standard 1/4" blade type fuse. Is
> >there a better way or will the inline fuse work just fine?
> >
> >Thanks,
> >Travis
> >RV-7A wiring
> >
> >
> >
>
>
>--
>No virus found in this incoming message.
>
>
>-- incoming mail is certified Virus Free.
Bob . . .
--------------------------------------------------------
< Throughout history, poverty is the normal condition >
< of man. Advances which permit this norm to be >
< exceeded -- here and there, now and then -- are the >
< work of an extremely small minority, frequently >
< despised, often condemned, and almost always opposed >
< by all right-thinking people. Whenever this tiny >
< minority is kept from creating, or (as sometimes >
< happens) is driven out of a society, the people >
< then slip back into abject poverty. >
< >
< This is known as "bad luck". >
< -Lazarus Long- >
<------------------------------------------------------>
http://www.aeroelectric.com
Message 11
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| Subject: | Re: Fw: Diodes for Master and Starter relays |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
The Zener-Zener is usually called a Transient Voltage Suppressor(TVS). I
use the term transorb that can be likened to Kleenex. (Its two "zeners" back
to back in one package)
Any way, one useful part is the P6KE18CA. The A at the end says its
bidirectional. Its a 600 watt 18V (start of clipping) transorb. Use
www.findchips.com for popular brands and sources. Variety of sources and
brands with suprisingly wide range of pricing.
Personally I prefer the 1.5KE18CA (1,500 watt) because it has larger
diameter leads and should be less likely to break. 600 watt is overkill in
power rating. Its picking a physical size you are comfortable with.
Paul
----- Original Message -----
From: "Joe & Jan Connell" <jconnell@rconnect.com>
Subject: AeroElectric-List: Fw: Diodes for Master and Starter relays
> --> AeroElectric-List message posted by: "Joe & Jan Connell"
> <jconnell@rconnect.com>
>
> Hi Guys,
>
> Thanks for all your discussion on this topic. In review of
> http://relays.tycoelectronics.com/kilovac/appnotes/transients.stm
> it appears the zener-zener method is preferred. After searching
> through the Digikey catalog it looks like I should get a pair of zener
> diodes, solder the cathode ends together, and connect the anode
> ends to relay terminals after covering them with heat-shrink tubing.
>
> Am I in the ball park on this?
> Are 5 watt, 16 volt zener diodes acceptible?
>
> Looks like I can do this for a couple of bucks. All I really need are
> part numbers, wattages, and voltages. I don't have the background
> to process the technical nuances of the various solutions.
>
> Thanks again...
>
> Joe Connell
> Stewartville, MN
> RV-9A N95JJ wiring
>
>
>
Message 12
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| Subject: | Re: Circuit breaker ratings for OVP |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 04:24 PM 3/23/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
> >>--> AeroElectric-List message posted by: "Eric M. Jones"
><emjones@charter.net>
> >>
> >>It would seem improbably at best that a circuit breaker could be built to
> >>survive an arbitrarily large overcurrent. As Paul has pointed out, the
> >>addition of a small resistor will put this crowbar back into the barn.
> >>snip
>
> >But is it an arbitrarilly large current at the specified voltages and
> >with wires that can reasonably be attached to the device? One of the
> >examples mentioned about 35 miliohms resistance for the breaker. Well if
> >a 12volt battery is pulled down to say 10 volts then you simply can't
> >get more than 10 / 0.035 =286 amps even with a zero impedance (at 10
> >volts) battery and zero resistance wires and connectors! But it would be
> >less with real wires, real connectors, and a real battery. OK double
> >that for a 24 volt system but it still isn't arbitrarilly large.
>
>Ken,
>
>I didn't mean infinitely large. I meant some amount over the 1000% limit
>specified by the CB manufacturer. The point is that Bob's white paper
>assumed you could extend the curves...and well...I don't think you can.
I've been really tied up on a couple of fire-fights at RAC and
wasn't able to get as much data on this issue as I'd like. Preliminary
discussions with folks in the mil-spec breaker business have failed
to uncover demonstrable reasons for the 1000% "limit" on max interrupt
current for resetability and no degradation of breaker performance.
I've asked about a half dozen of the ol' salts at RAC about this
and it was a new issue to them. As soon as I get at least one of these
fires out, I'll dig into the documentation and history. My favorite
switch/breaker/contactor guru with Eaton/Cutler-Hammer is out of
town until next Monday. I'm going to see what if any foundation
supports what appears to be an industry wide practice.
Bob . . .
Message 13
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| Subject: | Re: Diodes for Master and Strater relays |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Bob; Your reply does not answer Joe's question. He is responding to the
relay manufacturers position that a simple diode is not the best way, nor
the second best way, nor the third best way etc.
Granted we need to do something but lets forget the widely used and not a
good way to deal with inductive kicks. The delay in opening and potential
welding of contactor contacts is reason enough to change the part from not
so good to best.
Paul
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Diodes for Master and Strater relays
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 09:36 AM 3/24/2005 -0600, you wrote:
>
>>--> AeroElectric-List message posted by: "Joe & Jan Connell"
>><jconnell@rconnect.com>
>>
>>Hi Guys,
>>
>>I've been searching the AeroElectric-List and the RV-list to
>>get information on which diode to use across these relays.
>>Can you provide me a diode part number and ratings? I'd
>>rather not buy the prepackaged solution from Van's...
>
> ANY diode will work. There's not a rectifier diode
> made that doesn't have sufficient current and voltage
> ratings to do the task. My persona favorites are the
> 1N5400 series devices. You can get them from Radio
> Shack in packages of 2 for about $1.50
>
> See:
>
> http://www.aeroelectric.com/Pictures/RS_Diodes.jpg
>
> These have some mechanical robustness that makes them
> easier to work with and more resistant to mechanical
> failure in service. See:
>
> http://www.aeroelectric.com/Pictures/s701-1l.jpg
> http://www.aeroelectric.com/Pictures/s701-2.jpg
>
> You can find some starter contactors having built
> in diodes. This was the variety we used to sell.
> The contactors we sold said "diode protected"
> right on the base. When in doubt, put an external
> diode on . . . two diodes doesn't hurt but no
> diode can be a problem See:
>
> http://aeroelectric.com/articles/spikecatcher.pdf
>
> Bob . . .
>
>
>
Message 14
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| Subject: | Re: Circuit breaker ratings for OVP |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Perhaps this is in the same category of the widespread practice of the use
of rectifier diodes for relay coil spike suppression. Some manufacturers
provide the relates with diodes (or resistors) built in.
This does not mean its the best way but its what customers have demanded.
Back to the CB ratings. In one case I found where the CB had the 10X number
called out in its specification. Thus if you use this device to break more
than 10X its ratings you are exceeding its specifications regardless of any
real or unreal true damage limit.
The foundation for this limit may or may still apply but until the specs are
revised we should always respect the specification limits. Its foolish not
to do so. If there are no limits specified than does not mean we can expect
no damage at the upper current limit for breaking of 2000 amps.
Also the original foundation for any specific limits may have been lost over
time considering these parts have been in production longer than the normal
working life span of most of us.
I for one do not want to use parts outside their ratings regardless of the
validity of such ratings. In any event what I may do personally, I would
never consider recommending the application of any part outside its rating
for use by others.
SO on this list it seems to me we must consider the 10X as a hard number and
have available designs that do not suggest its OK to go outside the
specifications because there is (or may be) no apparent foundation for that
specification number. Also in this case there is simply no reason to do so
as there are designs that do not violate specifications.
Until the specificationis are physically revised, I will never consider
recommending anyone break the spec because we know its not real.
Paul
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Circuit breaker ratings for OVP
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 04:24 PM 3/23/2005 -0500, you wrote:
>
>>--> AeroElectric-List message posted by: "Eric M. Jones"
>><emjones@charter.net>
>>
>>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>>
>> >>--> AeroElectric-List message posted by: "Eric M. Jones"
>><emjones@charter.net>
>> >>
>> >>It would seem improbably at best that a circuit breaker could be built
>> >>to
>> >>survive an arbitrarily large overcurrent. As Paul has pointed out, the
>> >>addition of a small resistor will put this crowbar back into the barn.
>> >>snip
>>
>> >But is it an arbitrarilly large current at the specified voltages and
>> >with wires that can reasonably be attached to the device? One of the
>> >examples mentioned about 35 miliohms resistance for the breaker. Well if
>> >a 12volt battery is pulled down to say 10 volts then you simply can't
>> >get more than 10 / 0.035 =286 amps even with a zero impedance (at 10
>> >volts) battery and zero resistance wires and connectors! But it would be
>> >less with real wires, real connectors, and a real battery. OK double
>> >that for a 24 volt system but it still isn't arbitrarilly large.
>>
>>Ken,
>>
>>I didn't mean infinitely large. I meant some amount over the 1000% limit
>>specified by the CB manufacturer. The point is that Bob's white paper
>>assumed you could extend the curves...and well...I don't think you can.
>
> I've been really tied up on a couple of fire-fights at RAC and
> wasn't able to get as much data on this issue as I'd like. Preliminary
> discussions with folks in the mil-spec breaker business have failed
> to uncover demonstrable reasons for the 1000% "limit" on max interrupt
> current for resetability and no degradation of breaker performance.
>
> I've asked about a half dozen of the ol' salts at RAC about this
> and it was a new issue to them. As soon as I get at least one of these
> fires out, I'll dig into the documentation and history. My favorite
> switch/breaker/contactor guru with Eaton/Cutler-Hammer is out of
> town until next Monday. I'm going to see what if any foundation
> supports what appears to be an industry wide practice.
>
> Bob . . .
>
>
>
Message 15
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| Subject: | Re: Diode question |
--> AeroElectric-List message posted by: "Bob C. " <flyboy.bob@gmail.com>
Bob,
What is the maximum current you suggest for the e-bus?
Thanks,
Bob
On Fri, 25 Mar 2005 10:40:25 -0600, Robert L. Nuckolls, III
<b.nuckolls@cox.net> wrote:
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
>
> If you're needing to really LOAD up the e-bus normal feed
> diode this hard, I'm wondering if you have too much 'stuff'
> on the e-bus or perhaps the wrong z-figure selected for
> your airplane.
>
> Bob . . .
>
>
> At 06:07 PM 3/23/2005 -0500, you wrote:
>
> >--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
> >
> >Yellow PIDG faston terminals are available from digi-key in
> >(min.quantity 10) and work fine on 10 and 12 awg wire.
> >Ken
> >
> >Travis Hamblen wrote:
> >
> > >--> AeroElectric-List message posted by: "Travis Hamblen"
> > <TravisHamblen@cox.net>
> > >
> > >I am using Z-11 plan and have a couple questions that you guys will
> > >definitely know about. First, I am using the suggested steering diode
> > >between the main and essential bus (using the heat sink). The question is
> > >that because of the amperage I am sending through this diode ( < 25a but
> > >sometimes > 20a) I will be using 10awg wire which means I can't use a fast
> > >on terminal because they don't make them for awg that large. SO would a
> > >good alternative be to solder the wires to the fast on connectors on the
> > >diode? If I did this would it be just as secure, I was concerned that with
> > >all the vibration in an RV that the solder could break away after a while.
> > >I would prefer to use a fast on, but haven't been able to find fast ons for
> > >awg smaller than 14awg; if someone has a source for these please let me
> > >know!
> > >
> > >The second question is about the fuse that the steering diode calls for.
> > >The diode is only rated up to a max of 25a and this is a perfect match for
> > >my system. However, it also calls for the use of a breaker or fuse on the
> > >two wires going to the main bus. I was thinking of using an automotive
> > >style inline fuse that would use a 30a standard 1/4" blade type fuse. Is
> > >there a better way or will the inline fuse work just fine?
> > >
> > >Thanks,
> > >Travis
> > >RV-7A wiring
> > >
> > >
> > >
> >
> >
> >--
> >No virus found in this incoming message.
> >
> >
> >-- incoming mail is certified Virus Free.
>
> Bob . . .
>
> --------------------------------------------------------
> < Throughout history, poverty is the normal condition >
> < of man. Advances which permit this norm to be >
> < exceeded -- here and there, now and then -- are the >
> < work of an extremely small minority, frequently >
> < despised, often condemned, and almost always opposed >
> < by all right-thinking people. Whenever this tiny >
> < minority is kept from creating, or (as sometimes >
> < happens) is driven out of a society, the people >
> < then slip back into abject poverty. >
> < >
> < This is known as "bad luck". >
> < -Lazarus Long- >
> <------------------------------------------------------>
> http://www.aeroelectric.com
>
>
>
>
Message 16
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| Subject: | All this overvoltage stuff.... |
--> AeroElectric-List message posted by: "simon miles" <simon.miles@skynet.be>
You guys lost me some time ago with this subject...
I am about to start flying a homebuilt aeroplane fitted with a Rotax 912S
engine equipped with the standard alternator and no other generating device.
I intend to fly VFR only with an anticipated maximum electrical load of less
10 amps. I will fly day-time VFR only. All of my electrical installation has
been made according to Bob's recommendations and I am very happy with the
results - that is, my panel and radios power up without problem - however, I
haven't yet started the engine.
Do I need to worry about installing transorbs etc. or is my aeroplane
unlikely to be affected by the - to me, arcane - multitude of solutions to
potential problems provided by this list?
Simon Miles.
Message 17
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| Subject: | Re: All this overvoltage stuff.... |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: "simon miles"
<simon.miles@skynet.be>
>Do I need to worry about installing transorbs etc. or is my aeroplane
>unlikely to be affected by the - to me, arcane - multitude of solutions to
>potential problems provided by this list? Simon Miles.
Simon,
Every experiment needs a control sample. Thanks for volunteering. We will be
sending you a box with wires hanging out marked, "PLACEBO". Make sure you
install it per instructions--and don't open it.
Please keep us updated.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
Ring the bells that still can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in
- - Leonard Cohen
Message 18
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| Subject: | Re: All this overvoltage stuff.... |
--> AeroElectric-List message posted by: Dj Merrill <deej@thayer.dartmouth.edu>
Eric M. Jones wrote:
> Every experiment needs a control sample. Thanks for volunteering. We will be
> sending you a box with wires hanging out marked, "PLACEBO". Make sure you
> install it per instructions--and don't open it.
Oooo! I want one too! I've heard really
great things about that new PLACEBO technology!
*grin*
Simon, I've got Bob's recommended OV
setup in my Glasair, and I'm not changing a thing
at least until the debate produces a potential
alternate solution. I've been flying with it for a couple
of years now and have not seen any problems.
Just my half cents worth...
do not archive
-Dj
--
Dj Merrill
deej@thayer.dartmouth.edu
"TSA: Totally Screwing Aviation"
Message 19
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| Subject: | Re: Circuit breaker ratings for OVP |
--> AeroElectric-List message posted by: Andrew Rowley <arowley@ncable.net.au>
Paul Messinger wrote:
> Back to the CB ratings. In one case I found where the CB had the 10X number
> called out in its specification. Thus if you use this device to break more
> than 10X its ratings you are exceeding its specifications regardless of any
> real or unreal true damage limit.
>
> I for one do not want to use parts outside their ratings regardless of the
> validity of such ratings. In any event what I may do personally, I would
> never consider recommending the application of any part outside its rating
> for use by others.
>
> SO on this list it seems to me we must consider the 10X as a hard number and
> have available designs that do not suggest its OK to go outside the
> specifications because there is (or may be) no apparent foundation for that
> specification number. Also in this case there is simply no reason to do so
> as there are designs that do not violate specifications.
As someone already pointed out, circuit breakers are designed to protect
against short circuits, and your argument suggests you should replace a
circuit breaker if it trips and you can't determine whether the current
was within specifications.
The OVP is subjecting the circuit breaker to exactly the use it is
designed for. It is actually unusual in that you CAN determine in
advance the maximum current it will carry. Mostly maximum breaker
current would be determined by the location of the short.
Are you suggesting that in the general case where a breaker trips, if
you can't verify the maximum current was within specs, it should be
replaced? In that case it effectively becomes an expensive fuse.
Regards
--
Andrew Rowley
arowley@ncable.net.au
Message 20
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| Subject: | Re: Circuit breaker ratings for OVP |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
You have a point but in this case if the current version of the OVP trips
the CB you are 100% sure its broken a circuit well over the 10X CB spec
value.
If you are not sure perhaps its best to replace it but usually its possible
to estimate the current. Its up to you and / or your A&P.
On the other hand I have seen and heard about many cases of smoke in the
cockpit and never a CB tripping.
A wire in the harness shorting is quite rare.
Bob does not like CB's and this is one rare case where he recommends a CB. I
tend to agree. At least in this case.
Frankly a 100% reliable 0% false tripping OVP might be better coupled with a
Fuse. However I know of many cases of false tripping of this specific OVP
and Bob has acknowledged that it does rarely occur.
If we could be sure the only time the OVP popped the CB it was due to a
valid alternator failure then a fuse is a good choice. An all solid state
OVP can be made to never false trip if it is a part of a SYSTEM design that
takes care of load dumps or other short term transients.
Paul
----- Original Message -----
From: "Andrew Rowley" <arowley@ncable.net.au>
Subject: Re: AeroElectric-List: Re: Circuit breaker ratings for OVP
> --> AeroElectric-List message posted by: Andrew Rowley
> <arowley@ncable.net.au>
>
> Paul Messinger wrote:
>
>> Back to the CB ratings. In one case I found where the CB had the 10X
>> number
>> called out in its specification. Thus if you use this device to break
>> more
>> than 10X its ratings you are exceeding its specifications regardless of
>> any
>> real or unreal true damage limit.
>>
>
>> I for one do not want to use parts outside their ratings regardless of
>> the
>> validity of such ratings. In any event what I may do personally, I would
>> never consider recommending the application of any part outside its
>> rating
>> for use by others.
>>
>> SO on this list it seems to me we must consider the 10X as a hard number
>> and
>> have available designs that do not suggest its OK to go outside the
>> specifications because there is (or may be) no apparent foundation for
>> that
>> specification number. Also in this case there is simply no reason to do
>> so
>> as there are designs that do not violate specifications.
>
> As someone already pointed out, circuit breakers are designed to protect
> against short circuits, and your argument suggests you should replace a
> circuit breaker if it trips and you can't determine whether the current
> was within specifications.
>
> The OVP is subjecting the circuit breaker to exactly the use it is
> designed for. It is actually unusual in that you CAN determine in
> advance the maximum current it will carry. Mostly maximum breaker
> current would be determined by the location of the short.
>
> Are you suggesting that in the general case where a breaker trips, if
> you can't verify the maximum current was within specs, it should be
> replaced? In that case it effectively becomes an expensive fuse.
>
> Regards
>
> --
> Andrew Rowley
> arowley@ncable.net.au
>
>
>
Message 21
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| Subject: | Re: All this overvoltage stuff.... |
--> AeroElectric-List message posted by: "John Allen" <goldcare2@comcast.net>
I also have one of Bob's OV setup, and it works. 7 or 8 times it has popped
the 5 amp breaker/switch on my alternator when the output got to about
16.5v. I know what you're thinking. What dummy would keep flying for a month
or so and just keep resetting the breaker when the battery voltage dropper
too low. Well last summer I had this intermittent runaway alternator. It
would work ok for hours in cruse but on climb-out, just go nuts and Bob's OV
did it's thing just fine with no other damage. It wasn't much of a problem
as I only fly day vfr at present in my Volmer amfib. The flooded cell
battery seems to handle it ok and I only have 2 "handhelds" mounted and
wired in to the ships 12v supply. Finally I pulled the Chevy 60 amp
alternator from my custom mount on the aft end of my 0-200 pusher and found
the problem. The down stream side of the cooling system on a pusher gets
very hot, and the heat had softened the insulation in the cheap Radio Shack
shielded twin-lead wire that I used to run to the remote regulator mounted
next to the battery in the bilge.
When folks say they aren't having any problems, is it because the device
hasn't ever activated or did it activate and function properly. Well for me
it did activate several times. I don't know if it could damage other
electronic equipment, but my 2 radios and electronic fuel calculator still
seem ok. John Allen
Message 22
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
But a diode clamps the negative pulse to about 1 volt. Seems to me that
the difference may be significant to some electronic circuitry that is
sensitive to negative spikes.
Ken
Paul Messinger wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>The bidirectional transorbs clamp the negative spikes to less than 20 volts
>and also have no side affects of merit like contact bounce which is hard on
>contacts (not to mention making noise and other potentially nasty things).
>
>snip
>
Message 23
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| Subject: | Re: Diode question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 12:22 PM 3/25/2005 -0600, you wrote:
>--> AeroElectric-List message posted by: "Bob C. " <flyboy.bob@gmail.com>
>
>Bob,
>
>What is the maximum current you suggest for the e-bus?
>
>Thanks,
>Bob
It's not so much "maximum current" as how much stuff do you
need to run in the max endurance mode . . . I.e. main alternator
quits, no second alternator and battery only. Further, what's
your personal philosophy for battery only endurance? I've suggested
(and many builders have achieved) en route max endurance that
equals engine endurance for fuel aboard.
What are your personal desires? Have you reviewed chapter 17 in
the 'Connection?
Bob . . .
Message 24
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| Subject: | Re: Sigtronics intercom wiring and 12-channel annunciator |
--> AeroElectric-List message posted by: rv-9a-online <rv-9a-online@telus.net>
A few weeks ago there was a discussion on wiring a Sigtronics SPA-400
intercom, and how to deal with the 'forest of tabs' that resulted when
wiring.
I had some discussions off-list with a few of the contributors, and
decided to design a product based on their input. Rather than go into
advertorial mode, I'll direct any interested parties to the Vx Aviation
web site for more information:
http://www3.telus.net/aviation/vx see AMX-1A device.
Also, there was a lot of discussion on annuciator light controllers.
Although this discussion quickly evolved into speech synthesize alarms,
the fundamental problem of driving lamps, testing them and dimming them
while sensing active high and active low inputs has been solved for some
time with a 4-channel device (IL-4A). The requirements of the list
seemed to gravitate to a 12-channel controller, so I've made available a
12-channel device, the IL-12A. For more information see:
http://www3.telus.net/aviation/vx see IL-4A & IL-12A devices.
I hope that these products are of benefit to list members... they were
developed specifically to solve problems that have been debated on-list
recently. I try to listen for common problems, develop solutions and
make them available through Vx Aviation when it makes sense. It's a
service to the OBAM community, and allows me to stay involved in
electronics which I love.
Vern Little
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