Today's Message Index:
----------------------
1. 02:11 AM - Re: Re: S704-1 Relay Question (Andrew Butler)
2. 03:25 AM - Re: Any legacy regulator gurus out there? (jetboy)
3. 06:07 AM - battery tenders (bob noffs)
4. 06:35 AM - Re: Re: S704-1 Relay Question (Etienne Phillips)
5. 06:49 AM - Re: Contactor Locations (Robert L. Nuckolls, III)
6. 07:10 AM - Re: Re: S704-1 Relay Question (Robert L. Nuckolls, III)
7. 07:11 AM - Re: Re: Any legacy regulator gurus out there? (Robert L. Nuckolls, III)
8. 07:18 AM - Re: battery tenders (Robert L. Nuckolls, III)
9. 07:24 AM - Re: battery tenders (Robert L. Nuckolls, III)
10. 07:48 AM - Re: Re: S704-1 Relay Question (Andrew Butler)
11. 10:26 AM - Re: Re: S704-1 Relay Question ()
12. 04:48 PM - Re: Contactor Locations (Les Kearney)
13. 05:40 PM - Re: Contactor Locations (Robert L. Nuckolls, III)
14. 05:40 PM - Re: Re: S704-1 Relay Question (Robert L. Nuckolls, III)
15. 06:19 PM - Fuse and Breaker - one bus (Chris)
16. 07:53 PM - Re: Fuse and Breaker - one bus (Gaye and Vaughn)
17. 08:20 PM - Re: Contactor Locations (Fiveonepw@aol.com)
18. 08:37 PM - Re: Fuse and Breaker - one bus (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: S704-1 Relay Question |
Okay, I've read the Wikipedia and aeroelectric articles. So far so good.
So, in the absence of the diode, where is the "arc" likely to occur? If I
have understood correctly I'm saying at the E-BUS feed switch rather than
at the switch in the relay. Am I correct?
If not, why does the arc occur at the relay switch and not the feed
switch. It has to do with the current flow path.........
Thanks for your help.
Andrew.
----- Original Message -----
From: "Etienne Phillips"
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: Re: S704-1 Relay Question
Date: Mon, 19 May 2008 17:40:15 +0200
It's called a fly-back diode.
The coil of a relay is a fairly sizeable inductor, which means that a
step-change in current is not really possible. What happens when the
current to the coil is removed, the "inertia" of the inductor will
force a current to continue flowing for a short while, generating
large voltages and arcing across switch contacts. The fly-back diode
gives this current a path to flow without interfering with the rest
of the electrical system, and only comes into play when the coil is
de-energized.
For more info, go to http://en.wikipedia.org/wiki/Flyback_diode
:-)
Etienne
2008/5/19 Andrew Butler <andrewbutler@ireland.com>:
Thanks Ron, though the diode I was referring is the 1N4001 across
the coil of the S704 relay. There is something I don't know,
cause I don't see it adding any functionality.......
Andrew.
----- Original Message -----
From: "Ron Shannon"
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: Re: S704-1 Relay Question
Date: Mon, 19 May 2008 07:07:20 -0700
On Mon, May 19, 2008 at 6:11 AM, Andrew Butler <andrewbutler@ireland.
com>
wrote:
Hello,
At what level of load does an E-Bus become "heavy duty"?
Also, what is the purpose of the diode? I know what a
diode does, but what is its practical use in this
instance?
Cheers,
Andrew.
The level at which an E-bus becomes "heavy duty" is not a
precise point, but certainly occurs when the E-bus is
expected to carry loads that would strain or exceed limits
for a standalone toggle switch. Although the S700 series
switches are rated to 15A, you should probably be seriously
considering a separate relay whenever load approaches 10A,
IMHO.
The diode keeps the E-bus from back feeding the Main bus when
the E-bus alternate feed (direct from battery or battery bus)
is ON. If the E-bus were allowed to back feed the Main bus,
it would defeat the purpose of the E-bus, which is rapid,
positive reduction of load upon alternator failure. Use of a
diode instead of another switch eliminates the need to flip
another switch (i.e., reduces chance for error, also, see
"heavy duty" discussion above).
Ron
ist"> http://www.matronics.com/Navigator?AeroElectric-List
ics.com . matronics.com/contribution
===========
========
===
Message 2
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| Subject: | Re: Any legacy regulator gurus out there? |
Sir, I dont quite want to claim guru status, working on my previous C150A from
'61 it was similar and I did reset the V reg to around 14.4 - it was sitting
about 13 - and reset the I reg with a wirewound resistor (one of those old monster
types with the sliding clamp) to get the output up to 12 amps or so from
the 'as found' 6 amps. It was actually a 20 amp generator but 12 is enough when
the professional fix would be 100s of miles and $ away
I dont recall whether I altered the gaps or tension for this but I did it after
cleaning the contacts from 40 years of pitting with a burnishing tool.
Some time later I had a low charge again and discovered the aircraft master switch
- which thoughtfully includes cutoff contacts for the generator field line
- was in need of similar refurbishing. love these old systems because they are
actually repairable - just go to where the smoke last escaped from...
Moral of the story for me was I had wrongly assumed I knew enough not to check
the aircraft schematics first. In all probability the regulator may have been
OK but the worn switch in the field line had reduced the drive. It did no harm
checking the regulator and it would have been a shame to have it binned as it
looked like new inside just as the ones pictured. So I concur with your notion
to have him only mess with the V reg - perhaps after cleaning the contacts and
checking the other wiring for hidden resistance.
Ralph
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=183994#183994
Message 3
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earl,
a few years ago when battery tenders was a topic here i got started on
the h. f. units. i ran into a low voltagw problem. i remember a post
back then about the adjustable pots. i opened one up and no adjustable
pot. this was probably 2 years ago. that is why i shopped for them with
my voltmeter. i dont believe h. f. management will let me take them in
the backroom and test them anymore.
bob
noffs
Message 4
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| Subject: | Re: S704-1 Relay Question |
That is correct, in the E-bus Alternate Feed Switch in this case, or in a
more general case when dealing with inductor-like components, it'll arc
across whatever component tries to remove power to the relay. In the case of
a solid-state IC, this will normally be the silicon wafer, which would let
out the smoke and kill the chip.
I know someone who lost a starter switch in his Cozy after about 15 engine
starts because the fly-back diode was missing from the starter contactor,
that's how marked the effect is... A new switch and one 50c fly-back diode
later and no more problems.
Hope that helps :-)
Etienne
2008/5/20 Andrew Butler <andrewbutler@ireland.com>:
> Okay, I've read the Wikipedia and aeroelectric articles. So far so good.
>
> So, in the absence of the diode, where is the "arc" likely to occur? If I
> have understood correctly I'm saying at the E-BUS feed switch rather than at
> the switch in the relay. Am I correct?
>
> If not, why does the arc occur at the relay switch and not the feed switch.
> It has to do with the current flow path.........
>
> Thanks for your help.
>
> Andrew.
>
> ----- Original Message -----
> From: "Etienne Phillips"
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Re: S704-1 Relay Question
> Date: Mon, 19 May 2008 17:40:15 +0200
>
> It's called a fly-back diode.
>
> The coil of a relay is a fairly sizeable inductor, which means that a
> step-change in current is not really possible. What happens when the current
> to the coil is removed, the "inertia" of the inductor will force a current
> to continue flowing for a short while, generating large voltages and arcing
> across switch contacts. The fly-back diode gives this current a path to flow
> without interfering with the rest of the electrical system, and only comes
> into play when the coil is de-energized.
>
> For more info, go to http://en.wikipedia.org/wiki/Flyback_diode
>
> :-)
>
> Etienne
>
> 2008/5/19 Andrew Butler <andrewbutler@ireland.com>:
>
>> Thanks Ron, though the diode I was referring is the 1N4001 across the
>> coil of the S704 relay. There is something I don't know, cause I don't see
>> it adding any functionality.......
>>
>> Andrew.
>>
>> ----- Original Message -----
>> From: "Ron Shannon"
>> To: aeroelectric-list@matronics.com
>> Subject: Re: AeroElectric-List: Re: S704-1 Relay Question
>> Date: Mon, 19 May 2008 07:07:20 -0700
>>
>> On Mon, May 19, 2008 at 6:11 AM, Andrew Butler <andrewbutler@ireland.com>
>> wrote:
>>
>>> Hello,
>>>
>>> At what level of load does an E-Bus become "heavy duty"?
>>>
>>> Also, what is the purpose of the diode? I know what a diode does, but
>>> what is its practical use in this instance?
>>>
>>> Cheers,
>>>
>>> Andrew.
>>>
>>
>>
>> The level at which an E-bus becomes "heavy duty" is not a precise point,
>> but certainly occurs when the E-bus is expected to carry loads that would
>> strain or exceed limits for a standalone toggle switch. Although the S700
>> series switches are rated to 15A, you should probably be seriously
>> considering a separate relay whenever load approaches 10A, IMHO.
>>
>> The diode keeps the E-bus from back feeding the Main bus when the E-bus
>> alternate feed (direct from battery or battery bus) is ON. If the E-bus were
>> allowed to back feed the Main bus, it would defeat the purpose of the E-bus,
>> which is rapid, positive reduction of load upon alternator failure. Use of a
>> diode instead of another switch eliminates the need to flip another switch
>> (i.e., reduces chance for error, also, see "heavy duty" discussion above).
>>
>> Ron
>>
>> *
>>
>> ist">http://www.matronics.com/Navigator?AeroElectric-Listics.com
>> .matronics.com/contribution
>> *
>>
>>
>> *
>>
>> *
>>
>>
> *
>
> ist">http://www.matronics.com/Navigator?AeroElectric-Listics.com
> .matronics.com/contribution
> *
>
>
> *
>
>
> *
>
>
Message 5
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| Subject: | Re: Contactor Locations |
At 09:03 PM 5/19/2008 -0600, you wrote:
>Hi
>
>
>I am trying to plan my RV10 electrical system and have a question for the
>electrical mavens. That is, how far from avionics should battery
>contactors be? I am looking at mounting my batteries in the sub panel area
>and would like to co locate the contactors in the same area. Access is not
>an issue but I am concerned about possible interference with the avionics.
>I may end up locating the starter contactor on the same area as well.
>Would this be a problem?
>
>
>Cheers
>
>
>Les Kearney
Contactors are not high level antagonists to other
components of the system. You mount contactors where
it makes the most sense for their function. Battery
contactors close to batteries, starter contactors
close to starters, ect. In some architectures, they
can be clustered together.
In any case, there are no characteristics of a
contactor that makes them a threat to anything
other than the switch that controls them. See:
http://www.aeroelectric.com/articles/spikecatcher.pdf
http://www.aeroelectric.com/articles/spike.pdf
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 6
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| Subject: | Re: S704-1 Relay Question |
At 09:01 AM 5/20/2008 +0000, you wrote:
>Okay, I've read the Wikipedia and aeroelectric articles. So far so good.
>
>So, in the absence of the diode, where is the "arc" likely to occur? If I
>have understood correctly I'm saying at the E-BUS feed switch rather than
>at the switch in the relay. Am I correct?
>
>If not, why does the arc occur at the relay switch and not the feed
>switch. It has to do with the current flow path.........
>
>Thanks for your help.
>
>Andrew.
Not sure what you're calling the "feed switch". With
respect to contactors and relays, there is potential for
effects of field collapse in an inductor to erode
the contacts of the device that controls that contactor
or relay. Hence, the long standing practice of adding
spike suppression across the coils of such devices as
illustrated in the Z-figures.
Now, ANY time you break a circuit with the opening
of hard contacts as in a switch, relay or contactor
(that is carrying any amount of current at any voltage)
there WILL be an arc formed in spreading gap between
opening contacts. There was a school of thought circulated
in the OBAM aircraft community a few years ago that
for voltages and/or currents below some low level
(I don't recall the numbers now) that no arcing would
occur.
So as an experiment, I took a miniature switch and
sanded out the side of it like this:
http://aeroelectric.com/Pictures/Switches/sm_switch_cutaway.jpg
I fixtured it under the microscope and caused the
NO contacts to carry 1 or 1/2 amp of current at 1.5
volts (alkaline d-cell). In a dark room I could clearly
observe a tiny but bright blue arc in the spreading
gap between the contacts when the circuit was broken.
THIS ARCING IS NOT the phenomenon of concern with
respect to noise or debilitating effects on controlling
or controlled devices. Hence we rarely see arc suppression
techniques applied to these effects. One exception
is the quest for achieving the Beech Aircraft ov relay
trip-life using relays some 30+ years ago as described
in the chapter on OV Protection in the 'Connection.
There is also a school of thought that suggests plain
vanilla diodes across relay and contactor coils will
cause a slowing of contact spreading velocity and is
therefore an inducement to prolonged arcing at the
opening contacts.
Experiments on my bench showed that while adding a
diode did indeed cause a DELAY IN OPENING of the
contacts . . .
http://www.aeroelectric.com/Pictures/Curves/704-1DelayNoDiode.gif
http://www.aeroelectric.com/Pictures/Curves/704-1DelayWithDiode.gif
. . . use of the plain vanilla diode produced no
significant slowing of contact spreading velocity
once they started to move.
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif
In any case, the arcing produced either at controlling
switches -OR- contacts of the controlled devices IS
NOT a widespread threat for damage to other components
in the system. The strongest effect you'll experience
from the behavior of an unsuppressed relay or contactor
coil is a transient interference event. A few years ago
I helped a builder track down why opening his avionics
bus relay on an off-the-shelf integrated power distribution
system caused his ov protection to trip. A diode
across the relay coil fixed the problem.
Bob . . .
Message 7
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| Subject: | Re: Any legacy regulator gurus out there? |
At 03:21 AM 5/20/2008 -0700, you wrote:
>
>Sir, I dont quite want to claim guru status, working on my previous C150A
>from '61 it was similar and I did reset the V reg to around 14.4 - it was
>sitting about 13 - and reset the I reg with a wirewound resistor (one of
>those old monster types with the sliding clamp) to get the output up to 12
>amps or so from the 'as found' 6 amps. It was actually a 20 amp generator
>but 12 is enough when the professional fix would be 100s of miles and $ away
>
>I dont recall whether I altered the gaps or tension for this but I did it
>after cleaning the contacts from 40 years of pitting with a burnishing tool.
>
>Some time later I had a low charge again and discovered the aircraft
>master switch - which thoughtfully includes cutoff contacts for the
>generator field line - was in need of similar refurbishing. love these old
>systems because they are actually repairable - just go to where the smoke
>last escaped from...
>
>Moral of the story for me was I had wrongly assumed I knew enough not to
>check the aircraft schematics first. In all probability the regulator may
>have been OK but the worn switch in the field line had reduced the drive.
>It did no harm checking the regulator and it would have been a shame to
>have it binned as it looked like new inside just as the ones pictured. So
>I concur with your notion to have him only mess with the V reg - perhaps
>after cleaning the contacts and checking the other wiring for hidden
>resistance.
>
>Ralph
Thank you for sharing this. I'll include it in my compilation
of hands-on experiences to forward to the gentleman who also
has an old C-150!
Bob . . .
Message 8
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| Subject: | Re: battery tenders |
At 02:24 AM 5/20/2008 +0000, you wrote:
><earl_schroeder@juno.com>
>
>Hi db,
>The older 42292 [or whatever (the previous generation)]did have a variable
>resister on the circuit board. Nearly every one needed some adjustment as
>I have a dozen or so.
>
>I purchased a minimum order of 100 ohm pots to install in the newer
>units. I adjust them for 13.8 open circuit.
>
>I've repaired six or so [mine and others] as the common failure is the
>transformer wire disconnects where it attaches to the plug that plugs into
>the 110VAC. A sharp knife will separate the plastic housing around the
>transformer providing access. I thought originally that trying to start
>an engine with the unit connected would melt the solder at that joint but
>I'm not sure.
>
>For the money they are hard to beat but as some say, you get what you pay
>for..
>Earl
Yup. The first "Battery Charger" I purchased from H.F. was
this guy.
http://aeroelectric.com/Pictures/Battery_Chargers/HF_Chargers/Junk_1.jpg
It was simply a loosely regulated, low-level charger that
might be classed as a "trickle-charger". No smarts at all
meaning that its design did not attempt to produce a top-off
charge followed by a non-charging support of terminal voltage
for the purpose of offsetting internal leakage that would
eventually discharge the battery.
That device was evaluated years ago and it's a certainty
that newer devices intended to compete in an increasingly
sophisticated market will have improved features.
The problem is a simple experiment to benchmark their
performance for behavior and calibration which I will
do as time permits.
Bob . . .
Message 9
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| Subject: | Re: battery tenders |
At 02:24 AM 5/20/2008 +0000, you wrote:
><earl_schroeder@juno.com>
>
>Hi db,
>The older 42292 [or whatever (the previous generation)]did have a variable
>resister on the circuit board. Nearly every one needed some adjustment as
>I have a dozen or so.
>
>I purchased a minimum order of 100 ohm pots to install in the newer
>units. I adjust them for 13.8 open circuit.
>
>I've repaired six or so [mine and others] as the common failure is the
>transformer wire disconnects where it attaches to the plug that plugs into
>the 110VAC. A sharp knife will separate the plastic housing around the
>transformer providing access. I thought originally that trying to start
>an engine with the unit connected would melt the solder at that joint but
>I'm not sure.
>
>For the money they are hard to beat but as some say, you get what you pay
>for..
>Earl
>
>
>-- skyking135 wrote:
><
>
>I have one of the 42292 units and measured the output voltage on my
>particular unit to be around 12.7 volts, noload. It was only getting the
>battery up to about 12.3 volts; not enough to keep a good charge on a
>battery. So, being the curious one that I am, I popped open the cover to
>see if I could figure out how to adjust the output voltage. I found a
>spot on the circuit board for a varistor (VR1) that had a 55ohm resistor
>soldered in that postion. I figured that must adjust the output voltage.
>I simply replaced the 55ohm resistor with a 22ohm one I had on hand.
>That boosted the ouptut to a more respectable 13.2 volts. It still will
>only charge up to about 12.9 volts which is better than the 12.3 is was
>reaching before. I think I will adjust the resistor again to see if I
>can squeeze out a little more performance.
>
>Quality control is not high on the list of priorities with Harbor
>Freight. You get what you pay for.
The question that is more difficult to answer is how does
this product behave when LOADED with a discharged battery.
How much current does it put out, for how long and to what
terminal voltage? Does it produce a recharge voltage curve
that looks anything like this?
http://www.aeroelectric.com/Pictures/Curves/schumacher_2.jpg
The voltage you're measuring at very low output current
(open circuit) may be spoofing the charger into believing
that it's connected to a fully charged battery and causes
it to drop into the MAINTENANCE mode where the 12.9 volt
level you cited is quite acceptable.
A smart-charger is a crafty little bugger that takes
a bit more than a one-time voltmeter check to deduce
its capabilities. Adjusting them for a MAINTENANCE level
of 13.8 volts would be contrary to the design goals
for a true battery maintainer.
Bob . . .
Message 10
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| Subject: | Re: S704-1 Relay Question |
All I ever wanted to know about that particular component on the
Z-figures and then some.
I very much appreciate this valuable resource (all things Aeroelectric)
and your attention to detail Bob. I wired up my first harness last
weekend and attached it to my TruTrak servo. I did so with a relative
amount of confidence in what I was doing, how I was doing it, why I was
doing it and how I would continue doing it for the rest of the electrical
system. Fantastic!
Without this resource, I can honestly say that I would have been groping
in the dark ending up with a low quality piecemeal whole rather than a
high quality coherent one.
Very many thanks for this and for the answers to my future questions.
Andrew.
----- Original Message -----
From: "Robert L. Nuckolls, III"
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: Re: S704-1 Relay Question
Date: Tue, 20 May 2008 09:06:38 -0500
At 09:01 AM 5/20/2008 +0000, you wrote:
> Okay, I've read the Wikipedia and aeroelectric articles. So far so
good.
>
> So, in the absence of the diode, where is the "arc" likely to
occur? If I have understood
> correctly I'm saying at the E-BUS feed switch rather than at the
switch in the relay. Am I
> correct?
>
> If not, why does the arc occur at the relay switch and not the feed
switch. It has to do with
> the current flow path.........
>
> Thanks for your help.
>
> Andrew.
Not sure what you're calling the "feed switch". With
respect to contactors and relays, there is potential for
effects of field collapse in an inductor to erode
the contacts of the device that controls that contactor
or relay. Hence, the long standing practice of adding
spike suppression across the coils of such devices as
illustrated in the Z-figures.
Now, ANY time you break a circuit with the opening
of hard contacts as in a switch, relay or contactor
(that is carrying any amount of current at any voltage)
there WILL be an arc formed in spreading gap between
opening contacts. There was a school of thought circulated
in the OBAM aircraft community a few years ago that
for voltages and/or currents below some low level
(I don't recall the numbers now) that no arcing would
occur.
So as an experiment, I took a miniature switch and
sanded out the side of it like this:
http://aeroelectric.com/Pictures/Switches/sm_switch_cutaway.jpg
I fixtured it under the microscope and caused the
NO contacts to carry 1 or 1/2 amp of current at 1.5
volts (alkaline d-cell). In a dark room I could clearly
observe a tiny but bright blue arc in the spreading
gap between the contacts when the circuit was broken.
THIS ARCING IS NOT the phenomenon of concern with
respect to noise or debilitating effects on controlling
or controlled devices. Hence we rarely see arc suppression
techniques applied to these effects. One exception
is the quest for achieving the Beech Aircraft ov relay
trip-life using relays some 30+ years ago as described
in the chapter on OV Protection in the 'Connection.
There is also a school of thought that suggests plain
vanilla diodes across relay and contactor coils will
cause a slowing of contact spreading velocity and is
therefore an inducement to prolonged arcing at the
opening contacts.
Experiments on my bench showed that while adding a
diode did indeed cause a DELAY IN OPENING of the
contacts . . .
http://www.aeroelectric.com/Pictures/Curves/704-1DelayNoDiode.gif
http://www.aeroelectric.com/Pictures/Curves/704-1DelayWithDiode.gif
. . . use of the plain vanilla diode produced no
significant slowing of contact spreading velocity
once they started to move.
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif
In any case, the arcing produced either at controlling
switches -OR- contacts of the controlled devices IS
NOT a widespread threat for damage to other components
in the system. The strongest effect you'll experience
from the behavior of an unsuppressed relay or contactor
coil is a transient interference event. A few years ago
I helped a builder track down why opening his avionics
bus relay on an off-the-shelf integrated power distribution
system caused his ov protection to trip. A diode
across the relay coil fixed the problem.
Bob . . .
===========
===========
===========
===========
Message 11
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| Subject: | Re: S704-1 Relay Question |
Great thread...
In our world it seems like we take relays for granted. They are amazing
gadgets and I wanted to find more information on them. Below is a great
link with detail on the very popular Bosch relay. It should be very
clear as to their great benefit. There is no reason to stress a switch
with a few of these in-line.
http://www.bcae1.com/relays.htm#demo
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Andrew Butler
Sent: Tuesday, May 20, 2008 10:45 AM
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: Re: S704-1 Relay Question
All I ever wanted to know about that particular component on the
Z-figures and then some.
I very much appreciate this valuable resource (all things
Aeroelectric) and your attention to detail Bob. I wired up my first
harness last weekend and attached it to my TruTrak servo. I did so with
a relative amount of confidence in what I was doing, how I was doing it,
why I was doing it and how I would continue doing it for the rest of the
electrical system. Fantastic!
Without this resource, I can honestly say that I would have been
groping in the dark ending up with a low quality piecemeal whole rather
than a high quality coherent one.
Very many thanks for this and for the answers to my future
questions. Andrew.
----- Original Message -----
From: "Robert L. Nuckolls, III"
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: Re: S704-1 Relay
Question
Date: Tue, 20 May 2008 09:06:38 -0500
Nuckolls, III"
At 09:01 AM 5/20/2008 +0000, you wrote:
> Okay, I've read the Wikipedia and aeroelectric
articles. So far so good.
>
> So, in the absence of the diode, where is the "arc"
likely to occur? If I have understood
> correctly I'm saying at the E-BUS feed switch rather
than at the switch in the relay. Am I
> correct?
>
> If not, why does the arc occur at the relay switch and
not the feed switch. It has to do with
> the current flow path.........
>
> Thanks for your help.
>
> Andrew.
Not sure what you're calling the "feed switch". With
respect to contactors and relays, there is potential for
effects of field collapse in an inductor to erode
the contacts of the device that controls that contactor
or relay. Hence, the long standing practice of adding
spike suppression across the coils of such devices as
illustrated in the Z-figures.
Now, ANY time you break a circuit with the opening
of hard contacts as in a switch, relay or contactor
(that is carrying any amount of current at any voltage)
there WILL be an arc formed in spreading gap between
opening contacts. There was a school of thought
circulated
in the OBAM aircraft community a few years ago that
for voltages and/or currents below some low level
(I don't recall the numbers now) that no arcing would
occur.
So as an experiment, I took a miniature switch and
sanded out the side of it like this:
http://aeroelectric.com/Pictures/Switches/sm_switch_cutaway.jpg
I fixtured it under the microscope and caused the
NO contacts to carry 1 or 1/2 amp of current at 1.5
volts (alkaline d-cell). In a dark room I could clearly
observe a tiny but bright blue arc in the spreading
gap between the contacts when the circuit was broken.
THIS ARCING IS NOT the phenomenon of concern with
respect to noise or debilitating effects on controlling
or controlled devices. Hence we rarely see arc
suppression
techniques applied to these effects. One exception
is the quest for achieving the Beech Aircraft ov relay
trip-life using relays some 30+ years ago as described
in the chapter on OV Protection in the 'Connection.
There is also a school of thought that suggests plain
vanilla diodes across relay and contactor coils will
cause a slowing of contact spreading velocity and is
therefore an inducement to prolonged arcing at the
opening contacts.
Experiments on my bench showed that while adding a
diode did indeed cause a DELAY IN OPENING of the
contacts . . .
http://www.aeroelectric.com/Pictures/Curves/704-1DelayNoDiode.gif
http://www.aeroelectric.com/Pictures/Curves/704-1DelayWithDiode.gif
. . . use of the plain vanilla diode produced no
significant slowing of contact spreading velocity
once they started to move.
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif
http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gi
f
In any case, the arcing produced either at controlling
switches -OR- contacts of the controlled devices IS
NOT a widespread threat for damage to other components
in the system. The strongest effect you'll experience
from the behavior of an unsuppressed relay or contactor
coil is a transient interference event. A few years ago
I helped a builder track down why opening his avionics
bus relay on an off-the-shelf integrated power
distribution
system caused his ov protection to trip. A diode
across the relay coil fixed the problem.
Bob . . .
==========
==========
==========
==========
Message 12
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| Subject: | Contactor Locations |
Bob
Thanks for the help. I read in the Aeroelectric Guide that the contactor
locations was not a big issue but wasn't sure how much flexibility I really
had.
A quick follow-up question: Will the electromagnets in the contactors be a
problem for any avionics. My Magnometers will be in the tail so that is not
a concern.
Cheers
Les
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: May-20-08 7:45 AM
Subject: Re: AeroElectric-List: Contactor Locations
<nuckolls.bob@cox.net>
At 09:03 PM 5/19/2008 -0600, you wrote:
>Hi
>
>
>I am trying to plan my RV10 electrical system and have a question for the
>electrical mavens. That is, how far from avionics should battery
>contactors be? I am looking at mounting my batteries in the sub panel area
>and would like to co locate the contactors in the same area. Access is not
>an issue but I am concerned about possible interference with the avionics.
>I may end up locating the starter contactor on the same area as well.
>Would this be a problem?
>
>
>Cheers
>
>
>Les Kearney
Contactors are not high level antagonists to other
components of the system. You mount contactors where
it makes the most sense for their function. Battery
contactors close to batteries, starter contactors
close to starters, ect. In some architectures, they
can be clustered together.
In any case, there are no characteristics of a
contactor that makes them a threat to anything
other than the switch that controls them. See:
http://www.aeroelectric.com/articles/spikecatcher.pdf
http://www.aeroelectric.com/articles/spike.pdf
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 13
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| Subject: | Contactor Locations |
At 05:43 PM 5/20/2008 -0600, you wrote:
>
>Bob
>
>Thanks for the help. I read in the Aeroelectric Guide that the contactor
>locations was not a big issue but wasn't sure how much flexibility I really
>had.
>
>A quick follow-up question: Will the electromagnets in the contactors be a
>problem for any avionics. My Magnometers will be in the tail so that is not
>a concern.
>
Magnetometers ARE a potential victim of stray magnetic
leakage from contactors but as a rule, if your magnetometer
is at least 3' away from a potential antagonist, you're
on solid ground. Another potential worry is stray field
from the SD-20 alternator. We had problems with interference
for a whisky compass mounted on the glare shield of
the A36 . . . but the problem went away when the compass
was moved upward about 10" onto the windshield.
The effects of a potential antagonist on a magnetic
navigation instrument is greatly attenuated by distance
. . . a few more inches separation can make a lot of
difference.
On heavy iron birds, we usually mount magnetometers
out in a wing just ahead of ailerons and use non-magnetic
stainless fasteners in the immediate vicinity.
Bob . . .
Message 14
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| Subject: | Re: S704-1 Relay Question |
At 02:45 PM 5/20/2008 +0000, you wrote:
>All I ever wanted to know about that particular component on the Z-figures
>and then some.
>
>I very much appreciate this valuable resource (all things Aeroelectric)
>and your attention to detail Bob. I wired up my first harness last weekend
>and attached it to my TruTrak servo. I did so with a relative amount of
>confidence in what I was doing, how I was doing it, why I was doing it and
>how I would continue doing it for the rest of the electrical system. Fantastic!
>
>Without this resource, I can honestly say that I would have been groping
>in the dark ending up with a low quality piecemeal whole rather than a
>high quality coherent one.
>
>Very many thanks for this and for the answers to my future questions. Andrew.
You're most welcome my friend. I'm pleased that you've
found the work so useful.
Bob . . .
Message 15
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| Subject: | Fuse and Breaker - one bus |
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: | Re: Fuse and Breaker - one bus |
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>
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 17
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| Subject: | Re: Contactor Locations |
In a message dated 05/20/2008 8:51:48 AM Central Daylight Time,
nuckolls.bob@cox.net writes:
In any case, there are no characteristics of a
contactor that makes them a threat to anything
other than the switch that controls them.
>>>
Be advised that mounting the master contactor next to your whiskey compass
may result in undesired consequenses...
8-)
Mark do not archive
**************Wondering what's for Dinner Tonight? Get new twists on family
favorites at AOL Food.
(http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001)
Message 18
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| Subject: | Re: Fuse and Breaker - one bus |
At 09:16 AM 5/20/2008 -0400, you wrote:
>
>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 . . .
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