Today's Message Index:
----------------------
1. 01:07 AM - Re: Vans Fuel Pump issue (Denny Mortensen)
2. 04:30 AM - Re: Cessna A-510 ignition switch (Harley)
3. 07:44 AM - TVS post (Christopher Stone)
4. 08:29 AM - Antenna Triplexer (Wayne Berg)
5. 09:25 AM - Re: Vans Fuel Pump issue (Walter Tondu)
6. 09:43 AM - Re: Re: Diodes across relay coils (Paul Messinger)
7. 09:43 AM - Re: Re: Diodes across relay coils (Paul Messinger)
8. 09:43 AM - Re: Re: Diodes across relay coils (Paul Messinger)
9. 09:43 AM - Re: Re: Diodes across relay coils (Leo Corbalis)
10. 11:37 AM - Re: Cessna A-510 ignition switch (Eric M. Jones)
11. 11:47 AM - Re: Antenna Triplexer (Robert L. Nuckolls, III)
12. 11:52 AM - Re: Re: Diodes across relay coils (Robert L. Nuckolls, III)
13. 11:55 AM - Re: Re: Cessna A-510 ignition switch (Dj Merrill)
14. 12:16 PM - Re: Re: Diodes across relay coils (Robert L. Nuckolls, III)
15. 12:43 PM - Great Leap Backwards? ()
16. 12:49 PM - Re: Re: Diodes across relay coils (Robert L. Nuckolls, III)
17. 12:58 PM - Re: Re: Diodes across relay coils (Robert L. Nuckolls, III)
18. 01:07 PM - DIY Navigation Antenna Questions ()
19. 01:28 PM - Re: Re: Diodes across relay coils (Robert L. Nuckolls, III)
20. 01:33 PM - Re: Great Leap Backwards? (Robert L. Nuckolls, III)
21. 01:50 PM - Re: Great Leap Backwards? (Matt Prather)
22. 01:54 PM - Re: Great Leap Backwards? (Dj Merrill)
23. 01:56 PM - Re: Re: Diodes across relay coils (Paul Messinger)
24. 01:56 PM - Re: Re: Diodes across relay coils (Paul Messinger)
25. 02:09 PM - Re: Great Leap Backwards? ()
26. 02:09 PM - Re: Great Leap Backwards? (Greg Young)
27. 02:12 PM - Re: Great Leap Backwards? (Matt Dralle)
28. 02:22 PM - electrical questions (long) (B Tomm)
29. 02:33 PM - Re: Great Leap Backwards? (Rob Housman)
30. 04:24 PM - Re: Great Leap Backwards? (BobsV35B@aol.com)
31. 08:03 PM - Re: Re: Diodes across relay coils (George Braly)
Message 1
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| Subject: | Vans Fuel Pump issue |
--> AeroElectric-List message posted by: "Denny Mortensen" <dennymortensen@cableone.net>
Might also try disconnecting the + wire from the pump and insulate so as
not to short. Then flip your switch to see if it still blows a fuse. If
it does your problem is in the wiring if not then try your pump.
Denny
-----Original Message-----
Sounds like the pump is where the fault lies. But you need to isolate
the pump from the rest of the system to prove that.
Take the pump out of the plane and try it on the bench using either a
current-limited supply or a 5A fuse -- no switch, just wires from supply
+12V to fuse to pump, and pump back to supply ground.
Frank
Message 2
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| Subject: | Re: Cessna A-510 ignition switch |
--> AeroElectric-List message posted by: Harley <harley@agelesswings.com>
Morning, DJ...
>>I'm dumping it and replacing it with two switches and a push button.<<
Probably a good idea in any case...that's exactly what I'm going to do,
and for the reasons you mentioned...also, judging from the size and
weight of the key switch that I have, two toggles and a push button will
save weight! Not to mention all the weight of that key itself that
resides in the switch when flying! <G>
As far as troubleshooting...since you're going to replace the key switch
anyway, take it right out, and while the wires are disconnected, start
the engine, then ground each mag p-lead just like you do through the
switch during your run up. You should be able to start it with the
wires disconnected from the switch, and see the normal rpm drop when
grounding the p-leads, with a complete shut down with both grounded.
If this is what happens, you won't have to look any further...if you
still have a problem, then follow some of the other suggestions that
have been mentioned.
Keep us informed!
Harley Dixon
Long EZ N28EZ
Canandaigua, NY
Dj Merrill wrote:
>--> AeroElectric-List message posted by: Dj Merrill <deej@thayer.dartmouth.edu>
>
> It was a dark and stormy night... Well, actually
>it was a bright and sunny day but it still scared me.
>While landing my Glasair, about halfway down the runway my engine quit.
>I was unable to get the engine restarted again, and after
>some limited troubleshooting I think I have traced the
>problem down to the ignition key switch. It is a
>Cessna key switch model A-510, part # C292501-0105.
>
> Would anyone happen to have a schematic for this
>key switch? I think the way it works is that it simply
>grounds (connects the p-lead wire to the
>p-lead shield which is grounded at the magneto)
>when switched to the OFF position, and leaves
>the p-lead disconnected (ie, "open") when in the
>BOTH position. Referring to Z-26 seems to follow this logic.
>Using my multimeter, I was able to
>determine that the p-leads for both mags are connected to
>the p-lead shield (ie, "grounded") in all four
>positions of the key switch, OFF, R, L, and BOTH.
>I measured this without removing any wires from
>the keyswitch.
>
> Am I on the right track, or should I be
>chasing some other gremlin? Should I remove
>the wires from the keyswitch and test it separately?
>
> If I do definitely determine that the
>keyswitch is the problem, I'm dumping it and replacing it
>with two switches and a push button. Seems silly to have
>a redundant ignition system tied to a single point of
>failure like this, especially after it scared the
>cr*p out of me.
>
>Thanks,
>
>-Dj
>
>
>
>
Message 3
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--> AeroElectric-List message posted by: Christopher Stone <rv8iator@earthlink.net>
Eric....
I believe you previousy posted a link to data on TVS (dueling zeners) devices.
I that had them bookmarked... But alas.
Would you repost?
You also had a PDF of the part you were or are going to offer for sale?
Thanks...
Chris Stone
Wiring RV-8, number one
Day/night VFR
Message 4
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| Subject: | Antenna Triplexer |
Seal-Send-Time: Mon, 28 Mar 2005 08:27:25 -0800
--> AeroElectric-List message posted by: "Wayne Berg" <wfberg@msn.com>
I have a Comant triplexer that reads very low resistance from each center conductor
to case. Is this normal?
Message 5
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| Subject: | Re: Vans Fuel Pump issue |
--> AeroElectric-List message posted by: Walter Tondu <walter@tondu.com>
On 03/27 9:55, Robert L. Nuckolls, III wrote:
> >I was doing the first check of the fuel boost pump today. I have
> >the standard electric pump and filter combo they sell for my IO-360M1B.
> >
> >Thought I would simply turn it on and off quickly to verify connectivity;
> >turn it on, hear some noise, turn it off.
> >
> >Blew a 5A fuse right away. Checked grounds - good. Checked positive
> >routing - good. Made sure positive and negatives were correct too.
> >Everything is ok as far as wiring. Wire size is adequate for both
> >positive and ground as well. And the switch seems to be working fine
> >as well.
> >
> >Tried it again, blew another 5A fuse immediately. In each trial,
> >the pump did not make any noise, just blew the fuse.
>
> What kind of pump is this? Is it a Fawcet or some motor
> driven device? If motor driven, know that it can have an
> inrush current many times that of running current. You may
> have to fuse it at a higher level and upsize the wires accordingly.
>
> Bob . . .
It's the Airflow Performance pump. I called the manufacturer
this morning to confirm the 5A fuse. Nope, use 10A as it's
initial draw is as high as 7A.
I'll give it a whirl.
Thanks to all who responded.
--
Walter Tondu
http://www.rv7-a.com
Message 6
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I understand. I have the same part/mfgr and they do start clamping on the
high side.
This one reason why we (Eric and I) recommend the use of multiple 1.5K
devices because they start at just ober 18 v and you add devices in paralles
based on the amp capacity of the alternator.
Also back to back unidirectional trqansorbs rated at say 18V will clamp at
around 1 V higher than a bidirectional 18V device.
Thanks for the info.
Paul
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 04:41 PM 3/27/2005 -0800, you wrote:
>
>>--> AeroElectric-List message posted by: "Paul Messinger"
>><paulm@olypen.com>
>>
>>A question. What were the transorbs you used (specific part # and BRAND).
>>The ones I have used clamped several AMPS to below 22V. This data was used
>>to demonstrate that a 40 amp load dump was limited to 24V or under with 3
>>1.5KE18C transorbs. I do not understand how one transorb allows the
>>voltage
>>to 25V at 700 ma I would expect a 700 ma pulse to peak well under 21V.
>>But
>>different brands do vary a surprising amount. Some 18V transorbs did not
>>really conduct much below 20V.
>
> They are 5KP18 by General Semiconductor. The data sheet calls
> for thresholds over a 22.0 to 24.4
>
>
>>The P6KECA I recently tested clamped a 1.0 Amp load at under 18.4V This is
>>a
>>true 18V bidirectional Transorb. Thus my question how how did you get 25V?
>
>
> These must be running at the top of spec. Add the forward drop
> of the second diode and you come out with 25.0
>
>>
Message 7
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 04:41 PM 3/27/2005 -0800, you wrote:
>
>>--> AeroElectric-List message posted by: "Paul Messinger"
>><paulm@olypen.com>
>>
>>The other main concern is the use of a diode on the "B" lead contactor can
>>delay the opening to well past the CB opening and in some cases with hi
>>current leads to the CB the contactor still has 8+ volts across the coil.
>
> How does it matter if there's a battery on line? Whether the ov system
> disconnects the alternator in 30 or 200 mS seems of little consequence
> at the end of the day.
It matters if the contactor is still in the process of opening when the OVP
opens the "B" lead. If the contacts of the "B" lead contactor are still
closed the load dump or failure will reappear on the acft bus until the
contacts finally open and when opening spew transients everywhere. The
transients from contact arcing may not be a concern but having 30+ ms of say
60V on the bus sure is a concern. My data of 50 ms to open with your data of
15 ms to open the CB leaves 35 ms of potential OV back on the bus and in
this case very likely a maxi sized load dump.
> I'm still not happy with the idea of internally regulated alternators.
I never was happy and neither were you as I recall. Its hard to plug the
dike today however.
I think we both feel that todays solution of the crowbar may not cover all
the bases and the entire approach needs revisiting and we are both doing
this.
> If one subscribes to the reliable as prop-bolts scenario for the
> regulators, then OV protection can be left out. However, if one of
> those "prop-bolts" does break, the pilot has no way to shut it off . . .
> without adding the b-lead contactor. If the b-lead contactor is
> present, then you can automate the shutdown just as if it were an
> externally regulated alternator . . . but now you have issues with
> respect to b-lead contactor performance in opening a 100+ volt circuit
> and you still can't shut the puppy off completely. A $10 regulator can
> crap and take the field winding with it making the whole alternator
> pretty much trash.
>
> We can undoubtedly figure out a way to sense OV condition, open a b-lead
> contactor -AND- stall the alternator to prevent further damage to the
> alternator -AND- the b-lead contactor . . . but that becomes about as
> costly as modifying the alternator to bring out the field leads.
>
> Bob . . .
>
>
>
Message 8
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> The drop out delay and non-clean break is evident. These traces are
> probably not valid for service as b-lead contactor. When opening the
> b-lead of an alternator running ball-to-wall . . . voltage rise across
> spreading contacts is going to be spectacular. I'm not truly convinced
> that the b-lead contactor would survive a real ov event. The fire might
> never go out before the field windings burn up . . . but at least all
> that snort isn't hard coupled to the rest of the system.
With a heavy transorb on the alternator side of the "B" lead contactor the
voltage is clamped to reasonable level as far as the contactor contacts are
concerned. This is where the 5KW 18V transorb helps.
Also if the trip is false the alternator regulator is likely protected by
the transorb.
>
> I'm wondering if a second crowbar right across the b-lead isn't called
> for. Pull that puppy to ground which no only keeps the fire from
> building
> in the contactor but stalls the alternator as well. It cannot supply
> its own field and continue the OV event if there's no output. I'm
> thinking
> the energy dissipated in the b-lead crowbar would be less than that
> dissipated
> on the contactor coil breaker.
Not sure I agree here. Remember there are two sources of current to the
field. The internal connection from the "B" lead and the external "field"
connection. This connection actually supplies field power until there is
power produced by the alternator and the field power is switched to the "B"
lead. Thus there is a second source of power to the alternator that needs
attention.
Also stalling the alternator might have interesting side effects on the belt
drive.
That brings up a new question. Assuming there is a real (vs. false trip)
need to shutdown the alternator, the OVP trips but the alt switch on the
panel is still supplying power to the alternator field thru the internal
regulator. Depending on the regulator's fault it seems to me the alternator
can still be generating power. Also there is the possibility that the
internal "B" lead to regulator connection can reverse power the panel
mounted switch (and on to the acft bus) with a 'far too hi' voltage that was
the reason for the OVP action. Sneak path anyone??? Not sure how long the
fuse/CB would take to trip in this case.
Paul
Message 9
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Leo Corbalis" <leocorbalis@sbcglobal.net>
In the real world, if you're using a transistor to control the relay without
a diode it will work ONCE ! Then you put in a new transistor. If you're
using a switch and no diode, the switch contacts will (guaranteed) get
arced. Manufacturers don't test their switch life this way. It will take
longer to kill a switch but you will kill it.
Leo Corbalis
----- Original Message -----
From: "Joel Jacobs" <jj@sdf.lonestar.org>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: "Joel Jacobs"
> <jj@sdf.lonestar.org>
>
>
> ----- Original Message -----
> From: "Eric M. Jones" <emjones@charter.net>
> To: <aeroelectric-list@matronics.com>
> Subject: AeroElectric-List: Re: Diodes across relay coils
>
>> >The description of a "low-side" switching arrangement is basically the
>> same, except that the voltage will go to a large positive value.
>>
>> The transient is always negative.
>>
>
> No, it isn't.. It is always oppisate the applied voltage that energized
> the
> coil. In a low side switch, the low side of the coil is negative while
> the
> switch is closed and the spike will be positive when the switch opens.
>
> Joel
>
>
>
Message 10
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| Subject: | Re: Cessna A-510 ignition switch |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
--> AeroElectric-List message posted by: Dj Merrill
<deej@thayer.dartmouth.edu>
There was an AD on that switch. Google "A-510 Ignition Switch".
Eric
do not archive
Message 11
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| Subject: | Re: Antenna Triplexer |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 08:27 AM 3/28/2005 -0800, you wrote:
>--> AeroElectric-List message posted by: "Wayne Berg" <wfberg@msn.com>
>
>I have a Comant triplexer that reads very low resistance from each center
>conductor to case. Is this normal?
Probably. Dead shorts at DC (ohmmeter readings) are
anything but at VHF/UHF frequencies.
Bob . . .
Message 12
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 09:12 AM 3/28/2005 -0800, you wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>I understand. I have the same part/mfgr and they do start clamping on the
>high side.
>
>This one reason why we (Eric and I) recommend the use of multiple 1.5K
>devices because they start at just ober 18 v and you add devices in paralles
>based on the amp capacity of the alternator.
>
>Also back to back unidirectional trqansorbs rated at say 18V will clamp at
>around 1 V higher than a bidirectional 18V device.
>
>Thanks for the info.
>
>Paul
Not sure I embrace the notion of attempting to hold the bus
to 20v or less. This is a quantum shift in philosophy of
power quality limits. We've learned to live comfortably
in the 40v/100us, 20v/1sec world for over nearly 40 years.
I understand there are some new kids on the block that would
like to have that power quality philosophy relaxed . . . but
I'm not convinced this is a good thing for the industry as
a whole. I continue to mull this over . . .
Bob . . .
Message 13
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| Subject: | Re: Cessna A-510 ignition switch |
--> AeroElectric-List message posted by: Dj Merrill <deej@thayer.dartmouth.edu>
Eric M. Jones wrote:
> --> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>
> --> AeroElectric-List message posted by: Dj Merrill
> <deej@thayer.dartmouth.edu>
>
> There was an AD on that switch. Google "A-510 Ignition Switch".
>
> Eric
>
> do not archive
VERY interesting! Thank you!!!
do not archive
-Dj
--
Dj Merrill
deej@thayer.dartmouth.edu
"TSA: Totally Screwing Aviation"
Message 14
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 09:32 AM 3/28/2005 -0800, you wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>
>----- Original Message -----
>From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
>To: <aeroelectric-list@matronics.com>
>Subject: Re: AeroElectric-List: Re: Diodes across relay coils
>
>
> > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> > <b.nuckolls@cox.net>
> >
>
> > The drop out delay and non-clean break is evident. These traces are
> > probably not valid for service as b-lead contactor. When opening the
> > b-lead of an alternator running ball-to-wall . . . voltage rise across
> > spreading contacts is going to be spectacular. I'm not truly convinced
> > that the b-lead contactor would survive a real ov event. The fire might
> > never go out before the field windings burn up . . . but at least all
> > that snort isn't hard coupled to the rest of the system.
>
>With a heavy transorb on the alternator side of the "B" lead contactor the
>voltage is clamped to reasonable level as far as the contactor contacts are
>concerned. This is where the 5KW 18V transorb helps.
If the alternator is in runaway mode, the transorbs are going to
be toast in seconds.
>Also if the trip is false the alternator regulator is likely protected by
>the transorb.
True . . . this is, I believe, what prompted consideration of a
voltage clamping devices in this location . . . but one still needs to
approach this with caution. As George Braly noted, he was able to
toast some transorbs in this location when breaking the b-lead of
a properly functioning alternator/regulator combination. I'm convinced
that his experience was driven by regulator/alternator dynamics . . . the
load dump produced a longer than average overshoot transient.
> > I'm wondering if a second crowbar right across the b-lead isn't called
> > for. Pull that puppy to ground which no only keeps the fire from
> > building in the contactor but stalls the alternator as well. It
> > cannot supply its own field and continue the OV event if there's
> > no output. I'm thinking
> > the energy dissipated in the b-lead crowbar would be less than that
> > dissipated
> > on the contactor coil breaker.
>
>Not sure I agree here. Remember there are two sources of current to the
>field. The internal connection from the "B" lead and the external "field"
>connection. This connection actually supplies field power until there is
>power produced by the alternator and the field power is switched to the "B"
>lead. Thus there is a second source of power to the alternator that needs
>attention.
Do we KNOW that an EXTERNAL hard source for field power or is it
simply a start up bias on the order of a few hundred milliamps?
The early alternator installations on cars depended on a startup
bias that came through the panel mounted alternator warning light.
If the light bulb burned out, the alternator wouldn't start. Later
systems included a resistor around the lamp so that the alternator
would start even if the bulb is open.
Even if this is a hard-source, I would expect it to be interrupted
by the first crowbar just as it is now . . .
>Also stalling the alternator might have interesting side effects on the belt
>drive.
How so? It's a 60A machine with limited output current. It won't
require much more torque to run it against a dead short than it does
to have it go into an OV condition against the battery.
>That brings up a new question. Assuming there is a real (vs. false trip)
>need to shutdown the alternator, the OVP trips but the alt switch on the
>panel is still supplying power to the alternator field thru the internal
>regulator.
??? Lost you here. Are we talking some configuration other than
Z-24? My intent there was to open the supply through the
control switch -AND- the open the alternator's b-lead. This leaves
the alternator totally disconnected from the rest of the aircraft's
electrical system.
> Depending on the regulator's fault it seems to me the alternator
>can still be generating power.
Absolutely. This is the source of my concern for putting the fire
out between spreading contacts of the b-lead contactor. If no mitigating
transorb is present, the failed alternator output could rise very
rapidly to voltages beyond what plain vanilla contactors are
designed to break. If a transorb is present, it's seems likely that
it will suffer the Braly effect and become toast. If it's a really
robust array of devices, they might just short and take the alternator
down gracefully. Or, they could take the route chosen by most plastic
devices and blow little bits of smoking plastic around the engine
compartment.
Now, this all takes time and the voltage might well stay down long
enough for the b-lead contactor to open and put the fires out between
spreading contacts.
> Also there is the possibility that the
>internal "B" lead to regulator connection can reverse power the panel
>mounted switch (and on to the acft bus) with a 'far too hi' voltage that was
>the reason for the OVP action. Sneak path anyone??? Not sure how long the
>fuse/CB would take to trip in this case.
Only if we're talking about something other than Z-24 . . .
When Z-24 was crafted, I could assume nothing about the internal
configuration of the alternator. If the bus voltage is too high,
it's time to totally unhook the alternator from the system. This
philosophy has functioned well with the few exceptions reported by
Van's . . . and again, I know (and can assume nothing) about Van's
alternators. I promised only to protect the aircraft. The alternator
had to be cut out on its own.
Bob . . .
Message 15
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| Subject: | Great Leap Backwards? |
--> AeroElectric-List message posted by: <bakerocb@cox.net>
3/28/2005
Hello Matt Dralle, I used to be able to go to the bottom of my lists, click
on Search, and get quickly to what I wanted to look for. It was one of the
most useful aspects of your lists.
Now I see something called Navigator at the bottom of my aeroelectric-list
and when I click on it it doesn't work at all. What is going on?
OC
PS: People, what I am searching for is the company that sells specially
designed hardware for installing radio boxes in instrument panels. Can you
please help me? Thanks.
Message 16
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
> >>The other main concern is the use of a diode on the "B" lead contactor can
> >>delay the opening to well past the CB opening and in some cases with hi
> >>current leads to the CB the contactor still has 8+ volts across the coil.
> >
> > How does it matter if there's a battery on line? Whether the ov system
> > disconnects the alternator in 30 or 200 mS seems of little consequence
> > at the end of the day.
>
>It matters if the contactor is still in the process of opening when the OVP
>opens the "B" lead. If the contacts of the "B" lead contactor are still
>closed the load dump or failure will reappear on the acft bus until the
>contacts finally open and when opening spew transients everywhere. The
>transients from contact arcing may not be a concern but having 30+ ms of say
>60V on the bus sure is a concern. My data of 50 ms to open with your data of
>15 ms to open the CB leaves 35 ms of potential OV back on the bus and in
>this case very likely a maxi sized load dump.
??? Lost you here. Until the contactor starts to break the b-lead
loose, the alternator is working at max effort to boost bus voltage.
Further, it's been successful to the extent that the ov protection has
sensed the event and started the process of shutting things down.
In the mean time, the battery will do what batteries do best and
keep enough load on the alternator to prevent a hazardous rise on the
bus. In the revision B discussion of the system dynamics paper
http://www.aeroelectric.com/articles/Crowbar_OV_Protection/DC_Power_System_Dynamics_C.pdf
I showed how a good battery will maintain bus voltage at or below
18 volts for hundreds of milliseconds . . . plenty of time for
bringing things to order in spite of stacked delays noted.
It's exactly this condition that drove the DO-160 to recommend that
14v appliances be designed to withstand 20 volts for 1 second . . .
FAR longer than it takes for the most sedentary ov protection system
to do the job.
> > I'm still not happy with the idea of internally regulated alternators.
>
>I never was happy and neither were you as I recall. Its hard to plug the
>dike today however.
I'm not sure we're obligated to "plug the dyke" . . . I'm certainly
interested seeing it we can teach ourselves to live with this
alternative technology. Alternative technologies have bubbled
up from time to time. Some proved to be good value and others
did not. We need to get all the facts together before the jury
is called.
>I think we both feel that todays solution of the crowbar may not cover all
>the bases and the entire approach needs revisiting and we are both doing
>this.
We're certainly marching off in that direction. I looked over the
alternator test stand that I acquired and found that it's too
badly abused to be worth resurrecting. I'm going back to plan-B.
I've got a 2 hp DC motor and drive controller that I'm going to
direct couple to an ND alternator with field leads brought out.
I really like this idea better anyhow because motor current is
directly proportional to output torque. I can observe and record
alternator drive torque under varying conditions. It will take
less time to build from scratch than to repair the other one
(which was fixed speed). Now all I need is more time.
Bob . . .
Message 17
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 09:44 AM 3/28/2005 -0800, you wrote:
>--> AeroElectric-List message posted by: "Leo Corbalis"
><leocorbalis@sbcglobal.net>
>
>In the real world, if you're using a transistor to control the relay without
>a diode it will work ONCE ! Then you put in a new transistor. If you're
>using a switch and no diode, the switch contacts will (guaranteed) get
>arced. Manufacturers don't test their switch life this way. It will take
>longer to kill a switch but you will kill it.
Sure . . . don't think anyone is arguing against inductive
spike suppression. Lots of techniques suffice to specific
task. The tests I did on the bench yesterday illustrated only
three of them.
Bob . . .
Message 18
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| Subject: | DIY Navigation Antenna Questions |
--> AeroElectric-List message posted by: <chaztuna@adelphia.net>
Bob,
Figure 13-12 on page 13-16 of the Aeroelectric Connection book shows a drawing
for making your own Navigation antenna. One section of this antenna calls for
a 90 degree bend in that section of 0.025" aluminum. The section's length is
called out as "convenient L", which I construe to mean a convenient length. The
width is called out as aluminum sheet angle 0.5" X 1.5". I construe this to
mean that the aluminum should be 1.5" wide on it's horizontal surface and 0.5"
on it's vertical (bent) surface.
Are my assumptions correct? Are there any recommended minimum or maximum lengths
for this section of angle? Is the 90 degree bend in this section to achieve
rigidity? Or, is this section of the antenna to be fastened to the outboard wing
rib? Please advise.
Charlie Kuss
RV-8A still wiring
Boca Raton, Florida
Message 19
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
<snip>
> > > I'm still not happy with the idea of internally regulated alternators.
> >
> >I never was happy and neither were you as I recall. Its hard to plug the
> >dike today however.
>
> I'm not sure we're obligated to "plug the dyke" . . .
Hmmm . . . interesting faux pas . . . wrote it only 30 minutes
and can't imagine where that came from!
Bob . . .
Message 20
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| Subject: | Re: Great Leap Backwards? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
At 03:42 PM 3/28/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: <bakerocb@cox.net>
>
>3/28/2005
>
>Hello Matt Dralle, I used to be able to go to the bottom of my lists, click
>on Search, and get quickly to what I wanted to look for. It was one of the
>most useful aspects of your lists.
>
>Now I see something called Navigator at the bottom of my aeroelectric-list
>and when I click on it it doesn't work at all. What is going on?
>
>OC
Matt doesn't monitor all the lists on his servers. If you want
to ask him a question, you'll have to direct it specifically to
him. However, the link below works for me in Netscape. Haven't
tried IE.
>PS: People, what I am searching for is the company that sells specially
>designed hardware for installing radio boxes in instrument panels. Can you
>please help me? Thanks.
Not sure what you're looking for here. I have dozens of hardware
catalogs but none that are uniquely "aircraft". What kind of device
are you looking for?
Bob . . .
Message 21
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| Subject: | Re: Great Leap Backwards? |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
I went to the Archive Search Engine:
http://www.matronics.com/searching/ws_script_short.cgi
and entered (after a couple of tries) "radio tray", and it returned a message
that included reference to:
http://www.radiorax.com/
Is that what you are looking for?
Regards,
Matt-
VE N34RD, C150 N714BK
> --> AeroElectric-List message posted by: <bakerocb@cox.net>
>
> 3/28/2005
>
> Hello Matt Dralle, I used to be able to go to the bottom of my lists,
> click on Search, and get quickly to what I wanted to look for. It was
> one of the most useful aspects of your lists.
>
> Now I see something called Navigator at the bottom of my
> aeroelectric-list and when I click on it it doesn't work at all. What
> is going on?
>
> OC
>
> PS: People, what I am searching for is the company that sells specially
> designed hardware for installing radio boxes in instrument panels. Can
> you please help me? Thanks.
>
>
Message 22
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|
| Subject: | Re: Great Leap Backwards? |
--> AeroElectric-List message posted by: Dj Merrill <deej@thayer.dartmouth.edu>
bakerocb@cox.net wrote:
> Hello Matt Dralle, I used to be able to go to the bottom of my lists, click
> on Search, and get quickly to what I wanted to look for. It was one of the
> most useful aspects of your lists.
>
> Now I see something called Navigator at the bottom of my aeroelectric-list
> and when I click on it it doesn't work at all. What is going on?
>
> OC
Hi OC,
You can get to the same thing by clicking the
"Navigator" link at the bottom of the e-mail.
That will take you to a page with the search
link on it. Matt did this since a bunch of people
were complaining about having the really long
list of links on every single e-mail message, and
this seemed like a good compromise. It amounts to
just one extra click to get to the same things.
fyi
-Dj
--
Dj Merrill
deej@thayer.dartmouth.edu
"TSA: Totally Screwing Aviation"
Message 23
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|
| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
I was not clear apparently.
I was simply replying to your test using different 18V transorbs that
allowed 25V.
The 1.5 watt transorbs will clamp to under 22V at 10 amps in testing. They
are soft zeners and I have photos where you can see the voltage rise during
the load dump from internal transorb die heating during the load dump event.
No way was I suggesting revising old standards in this case. I do believe in
improving power quality and I am in process of developing new methods that
do improve things.
Paul
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 09:12 AM 3/28/2005 -0800, you wrote:
>
>>--> AeroElectric-List message posted by: "Paul Messinger"
>><paulm@olypen.com>
>>
>>I understand. I have the same part/mfgr and they do start clamping on the
>>high side.
>>
>>This one reason why we (Eric and I) recommend the use of multiple 1.5K
>>devices because they start at just ober 18 v and you add devices in
>>paralles
>>based on the amp capacity of the alternator.
>>
>>Also back to back unidirectional trqansorbs rated at say 18V will clamp at
>>around 1 V higher than a bidirectional 18V device.
>>
>>Thanks for the info.
>>
>>Paul
>
> Not sure I embrace the notion of attempting to hold the bus
> to 20v or less. This is a quantum shift in philosophy of
> power quality limits. We've learned to live comfortably
> in the 40v/100us, 20v/1sec world for over nearly 40 years.
> I understand there are some new kids on the block that would
> like to have that power quality philosophy relaxed . . . but
> I'm not convinced this is a good thing for the industry as
> a whole. I continue to mull this over . . .
>
> Bob . . .
>
>
>
Message 24
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
----- Original Message -----
From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Re: Diodes across relay coils
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <b.nuckolls@cox.net>
>
> At 09:32 AM 3/28/2005 -0800, you wrote:
>
>>--> AeroElectric-List message posted by: "Paul Messinger"
>><paulm@olypen.com>
>>
>>
>>----- Original Message -----
>>From: "Robert L. Nuckolls, III" <b.nuckolls@cox.net>
>>To: <aeroelectric-list@matronics.com>
>>Subject: Re: AeroElectric-List: Re: Diodes across relay coils
>>
>>
>> > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
>> > <b.nuckolls@cox.net>
>>
> If the alternator is in runaway mode, the transorbs are going to
> be toast in seconds.
I agree. The transorb was onlt a solution if there was a false trip.
>
>>Also if the trip is false the alternator regulator is likely protected by
>>the transorb.
>
>
> True . . . this is, I believe, what prompted consideration of a
> voltage clamping devices in this location . . . but one still needs to
> approach this with caution. As George Braly noted, he was able to
> toast some transorbs in this location when breaking the b-lead of
> a properly functioning alternator/regulator combination. I'm convinced
> that his experience was driven by regulator/alternator dynamics . . .
> the
> load dump produced a longer than average overshoot transient.
Perhaps George will jump in but the 5KW transorb solution only is good for
14V systems. A 28V system which George also needs to deal with has lots more
energy to absorb.
>> > I'm wondering if a second crowbar right across the b-lead isn't
>> > called
>> > for. Pull that puppy to ground which no only keeps the fire from
>> > building in the contactor but stalls the alternator as well. It
>> > cannot supply its own field and continue the OV event if there's
>> > no output. I'm thinking
>> > the energy dissipated in the b-lead crowbar would be less than that
>> > dissipated
>> > on the contactor coil breaker.
>>
>>Not sure I agree here. Remember there are two sources of current to the
>>field. The internal connection from the "B" lead and the external "field"
>>connection. This connection actually supplies field power until there is
>>power produced by the alternator and the field power is switched to the
>>"B"
>>lead. Thus there is a second source of power to the alternator that needs
>>attention.
>
> Do we KNOW that an EXTERNAL hard source for field power or is it
> simply a start up bias on the order of a few hundred milliamps?
> The early alternator installations on cars depended on a startup
> bias that came through the panel mounted alternator warning light.
> If the light bulb burned out, the alternator wouldn't start. Later
> systems included a resistor around the lamp so that the alternator
> would start even if the bulb is open.
Understand but we simply do not know so I was simply speculating another
possible path of concern.//// SEE mind F*&
later in this post :-)
But also the alternator fuse would pop if the crowbar was in the right place
and might be a good solution but are we getting too complex for a very
unlikely event?
> Even if this is a hard-source, I would expect it to be interrupted
> by the first crowbar just as it is now . . .
>
>>That brings up a new question. Assuming there is a real (vs. false trip)
>>need to shutdown the alternator, the OVP trips but the alt switch on the
>>panel is still supplying power to the alternator field thru the internal
>>regulator.
>
> ??? Lost you here. Are we talking some configuration other than
> Z-24? My intent there was to open the supply through the
> control switch -AND- the open the alternator's b-lead. This leaves
> the alternator totally disconnected from the rest of the aircraft's
> electrical system.
OOPS sorry memory F*&
. My mind was somewhere else; you are right IF one
wires it properly.
My mind is getting as bad as my smelling of words or lack of :-)
You know, perhaps you should simply only support externally regulated
alternators and simply consider the internal regulator as being far more
reliable than a prop failure and worth the risk if the builder is informed.
Builders need to be informed and then when properly informed can make
informed decisions.
There is still the issue of disconnecting the battery and resulting load
dump but that has a very simple fix in Transorbs
Paul
> Bob . . .
Message 25
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| Subject: | Re: Great Leap Backwards? |
--> AeroElectric-List message posted by: <bakerocb@cox.net>
----- Original Message -----
From: "Matt Prather" <mprather@spro.net>
Subject: Re: AeroElectric-List: Great Leap Backwards?
>I went to the Archive Search Engine:
>
> http://www.matronics.com/searching/ws_script_short.cgi
>
> and entered (after a couple of tries) "radio tray", and it returned a
> message
> that included reference to:
>
> http://www.radiorax.com/
>
> Is that what you are looking for? Regards, Matt-
2/28/2005
Hello Matt Prather, Radiorax is exactly what I was looking for -- many
thanks.
I used to find direct access to the matronics search engine right at the
bottom of each aeroelectric list and go right to work. Recently there is a
"navigator" filter / barrier at the bottom of the lists. The first few times
I tried navigator it did not work. It seems to be working now, but I am
still not sure that hiding the various choices behind the word "navigator"
is progress.
Thanks again for your help.
OC
DO NOT ARCHIVE
Message 26
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| Subject: | Great Leap Backwards? |
--> AeroElectric-List message posted by: "Greg Young" <gyoung@cs-sol.com>
Are you thinking of Approach Systems that sells wiring hubs and cables?
http://www.approach-systems.com/
Or maybe Radiorax that sells a proprietary rack/rail installation
system?
http://www.radiorax.com/index.php
Regards,
Greg Young - Houston (DWH)
RV-6 N6GY ...project Phoenix
Navion N5221K - just an XXL RV-6A
> --> AeroElectric-List message posted by: <bakerocb@cox.net>
>
> 3/28/2005
>
> Hello Matt Dralle, I used to be able to go to the bottom of
> my lists, click on Search, and get quickly to what I wanted
> to look for. It was one of the most useful aspects of your lists.
>
> Now I see something called Navigator at the bottom of my
> aeroelectric-list and when I click on it it doesn't work at
> all. What is going on?
>
> OC
>
> PS: People, what I am searching for is the company that sells
> specially designed hardware for installing radio boxes in
> instrument panels. Can you please help me? Thanks.
>
Message 27
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|
| Subject: | Re: Great Leap Backwards? |
--> AeroElectric-List message posted by: Matt Dralle <dralle@matronics.com>
At 12:42 PM 3/28/2005 Monday, you wrote:
>--> AeroElectric-List message posted by: <bakerocb@cox.net>
>
>3/28/2005
>
>Hello Matt Dralle, I used to be able to go to the bottom of my lists, click
>on Search, and get quickly to what I wanted to look for. It was one of the
>most useful aspects of your lists.
>
>Now I see something called Navigator at the bottom of my aeroelectric-list
>and when I click on it it doesn't work at all. What is going on?
Whoops, sorry... I am doing maintenance on the Matronics webserver today
and it sounds like you tried to access the new page when it was unavailable...
I had gotten a number of complaints from members about the size of the old
style message trailer. I came up with the new, smaller version in hopes of
making everyone happy.
Do you still have the same complaint, if the line worked...?
PS- The webserver is up right now, but I will be taking it up and down a
few more times today.
Best regards,
Matt Dralle
Matronics Email List Admin
Matt G Dralle | Matronics | PO Box 347 | Livermore | CA | 94551
925-606-1001 V | 925-606-6281 F | dralle@matronics.com Email
http://www.matronics.com/ WWW | Featuring Products For Aircraft
Message 28
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| Subject: | electrical questions (long) |
--> AeroElectric-List message posted by: B Tomm <fvalarm@rapidnet.net>
Bob,
On my electrically dependant engine, I'm planning to have two battery
busses (fuse blocks) ala Z-19. The feed wires to these busses are to be
short as they are unfused. The recommended max length is 6 inches. I
assume that the shorter they are, the less likely they are to short to
ground creating trouble. My batteries will be mounted aft of the baggage
area (RV7A). I suppose I could fabricate a panel to mount the fuse block
busses but access would be difficult. The fuse blocks could be mounted
below the baggage floor with a removable cover which would be easier to
service BUT the unprotected feed would pass through a bulkhead. I would
think this is unwise, correct?
Should I fab a mounting bracket next to the batteries and a exterior access
panel to service the fuses?
Better yet, could I mount the battery busses (fuse blocks) behind the
instrument panel with the others buss blocks using a long feed wire from
the rear batteries and a fusible link at the batteries for protection? I
would prefer this method.
I would like to run one set of main battery feed lines from the pair of
rear mounted batteries to the firewall area. Contactors or better yet
(perihelion) solid state power relays would connect the batteries to these
feed lines. Why do some people recommended separate feed lines? I would
think these heavy wires are UNlikely failure points. Much weight can be
saved by eliminating this redundancy.
I'm not clear on how to size the wire for the main battery feed lines.
Some diagrams show 6,4, and even 2 AWG. The largest current draw for all
the electrical loads + starter can be calculated easy enough. The wire
table I have does not show current carrying capacity but resistance,
weight, 10C temp rise current and something called "CMA per amp". I
thought that we sized wire by some healthy factor over that which would
cause the wire to melt under max current draw. Since there is quite a bit
of weight involved here, and critical functions, this is important. Will a
single set of 6AWG be sufficient to start the Subaru?
I seem to recall that electrical wiring is to be kept some distance away
from fuel system components. Does this just apply to power wires. Are we
concerned about a broken live wire contacting a metalic fuel component such
as a fuel tube, or leaking fuel dripping on wires causing a short to
ground. In our small airplanes there will always be a potential for fuel
and fuel vapor contacting electrical components (we have aircooled radios).
Can you elaborate on wiring and fuel systems please or direct me to some
reference..
Your thoughts are appreciated and likely relavent to others as well.
Bevan
RV7A
Planning for H6 Subaru
Message 29
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| Subject: | Great Leap Backwards? |
--> AeroElectric-List message posted by: "Rob Housman" <robh@hyperion-ef.us>
Is this it? http://www.radiorax.com/
Best regards,
Rob Housman
Europa XS Tri-Gear A070
Airframe complete
Irvine, CA
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of
bakerocb@cox.net
Subject: AeroElectric-List: Great Leap Backwards?
--> AeroElectric-List message posted by: <bakerocb@cox.net>
3/28/2005
Hello Matt Dralle, I used to be able to go to the bottom of my lists, click
on Search, and get quickly to what I wanted to look for. It was one of the
most useful aspects of your lists.
Now I see something called Navigator at the bottom of my aeroelectric-list
and when I click on it it doesn't work at all. What is going on?
OC
PS: People, what I am searching for is the company that sells specially
designed hardware for installing radio boxes in instrument panels. Can you
please help me? Thanks.
Message 30
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| Subject: | Re: Great Leap Backwards? |
--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 3/28/2005 4:52:21 P.M. Central Standard Time,
mprather@spro.net writes:
PS: People, what I am searching for is the company that sells specially
> designed hardware for installing radio boxes in instrument panels. Can
> you please help me? Thanks.
Good Evening OC,
If you are thinking of using RadioRax, I have installed a set and like them
very much.
_www.radiorax.com_ (http://www.radiorax.com)
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Airpark LL22
Downers Grove, IL 60516
630 985-8502
Message 31
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| Subject: | Re: Diodes across relay coils |
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
Bob,
The load dumps that I have experienced on disconnecting 20 or 30 amps (resistive)
from the alternator were done under circumstances where the field was opened
within a couple of tenths of a millisecond (or even much faster) after the over
voltage threshold was crossed.
I'm not sure what regulator/alternator "dynamics" would cause the noted result,
other than just the ordinary load dump from the alternator.
>Also if the trip is false the alternator regulator is likely protected by
>the transorb.
True . . . this is, I believe, what prompted consideration of a
voltage clamping devices in this location . . . but one still needs to
approach this with caution. As George Braly noted, he was able to
toast some transorbs in this location when breaking the b-lead of
a properly functioning alternator/regulator combination. I'm convinced
that his experience was driven by regulator/alternator dynamics . . . the
load dump produced a longer than average overshoot transient.<<
BTW... I have a nice variable speed alternator test stand - - with an ND set
up on it and it is available if you want to fly down some Saturday morning and
see what we can do to blow up some transorbs or other components.
Regards, George
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